Transcript for:
Chemistry's Role in Anatomy and Physiology

hello MP class this is dr. class kit in this video I am going to go over some basic concepts of chemistry now bear with me I can already see a picture and some of those exasperated looks on your faces and I know that chemistry is not a very exciting topic for many of you but and you're probably also wondering why talk about chemical concepts when this is an anatomy and physiology class you have to trust me on this there are a lot of things that happen at the cellular level if you want to understand physiology of how organs work which is really broken down into four major types of tissues and then you can break down tissues into the cellular level if you really want to understand what's going on at the cellular level you have to break it down even further and understand what's going on at the chemical level so this is where I've got to explain the fundamentals of some of the chemistry how do atoms work what are molecules and some of the main concepts of chemical bonding so that you understand what's happening at the chemical level and then you can picture what's going on at the level of an organ or an organ system and that's how you and me work okay so what I'm gonna do right now is to share my screen so I can pull up my slides related to this topic and then we'll discuss the topic okay all right let me go ahead and get this started all right [Music] okay so this this set of slides is going to be a very very basic summary of the most important fundamental concepts of chemistry that we need to review very quickly before we can build on more complex topics yes there's more chemistry coming in my next video where we will talk about biochemistry and discuss the differences between organic and inorganic compounds okay but for right now let's keep it simple let's first talk about fundamentally what's an atom and what would you see inside of an atom like protons and neutrons and electrons and exactly how do they all fit into the big picture of forming chemical bonds okay so yes your body is inedible for a lot of different chemicals a lot of different elements okay and the reason for us diving off into some basic chemistry concepts is that you need to understand this before you understand physiology okay for example there are a lot of things in your body that are dictated by chemical processes like for example okay every cell in your body has an outer boundary called a cell membrane or a plasma membrane okay and the plasma membrane is a very selectively permeable membrane that allows certain substances to go back and forth in and out of the cell okay the movement or these transport processes are controlled by a lot of chemical concentrations of substances that you see outside of the cell and inside of the cell so we will talk about transport processes a little later on in in chapter 3 there are a lot of processes also within your body are like digestion the the cardiovascular system the nervous system all of these very very important organ systems that rely on chemical principles as well like for example for your heart to pump blood okay and this really all kind of revolves around the heart muscle the myocardium which is cardiac muscle so muscle needs to work as a unit okay so you've got if you kind of remember some of the basic anatomy of the heart you've got upper chambers called atria and you've got lower chambers called ventricles so when blood is pumped into the upper chambers the atria have to contract together to move that blood downwards into the lower ventricles and then the ventricles have to pump together to move all of that blood out into the major blood vessels like for example the aorta is one of them okay now for the entire cardiac muscle to work as a unit okay they need to communicate with each other and the chemical interactions between those muscle cells is what helps it to synchronously work as a unit and in fact calcium is one of those ions that are pumped that are exchanged between adjacent cardiac muscle cells that allows the entire unit to work as a whole the nervous system works through electrical signals called action potentials but that's intimately tied to chemical exchanges as well and so when we get to the second half of this chat of this semester you'll hear me talk a lot about the inner workings of the nervous system and that will also make sense at that time okay but for right now I'm gonna break down this entire concept of chemistry into one basic chemistry and two biochemistry okay so for this first set of slides I'm gonna dis discuss basic chemistry alright so um any chemical a substance is what we called matter matter is anything that occupies space and it has some kind of mass to it there are broadly speaking through three different states of matter a solid liquid and a gas and I'm sure you've heard a lot this back in school where you've learnt the the basic concepts of matter what what defines a solid versus a liquid and a gas okay so building upon this let's start what energy which is okay how do you put that matter into motion or action what is the capacity to do work with that matter now that is energy okay and so broadly speaking there's two different types of energy and that I want you to keep in mind to begin with potential energy and kinetic energy so potential energy is stored or inactive energy versus kinetic energy is actually converting that potential energy into something that loves matter or that mass to move okay so potential energy let's give an example if you were seated and you weren't really using your the muscles of your lower limbs your lower extremity like your gastrocnemius so your calf muscles okay so if you're not really moving and if you're in a seated position well there's a lot of energy that's being stored in those leg muscles okay the minute you stand up and start walking around well you're converting that stored potential energy in those muscles into something that is capable of movement and by movement I mean moving you as a person right and so that is an example of converting that stored energy potential energy within the muscles of your lower limbs your leg into kinetic energy okay and the cool thing about energy is that it can be transferred from one form of energy to another form of energy oftentimes though when there is conversion from one form to another okay it is not a very efficient process most of it is converted from one form to another but some part of it is lost in the form of heat okay now there are other forms of energy as well and that's what you see listed on this light okay so for example you've got chemical energy electrical energy mechanical or radiant electromagnetic energy so let's kind of talk about these different forms very quickly chemical energy is something you've got to keep in mind especially when we start discussing the digestive system which we don't do an ante one but if you take anp2 you'll definitely hear us talk about this quite a bit okay so and chemical energy is basically the energy that's stored in bonds of different chemical substances now the food that you eat is a chemical substance so the food the energy that is stored in that food is chemical energy okay and it needs to be transferred into would be called the energy currency of the cell and that's something called ATP adenosine triphosphate okay so this chemical energy when it is converted into this compound ATP it that energy is stored in the bonds of this molecule and that ATP is really really really important in the body to power many different cellular processes so in this regard let's quickly talk about cellular respiration okay this is a whole the whole kinds of chemical energy revolves around this process in your body and there's all lots that goes into this process of cellular respiration and again if you take anp2 we'll probably spend an entire lecture talking about chemical cellular respiration but for right now let's break this down as simplistically as we can okay any food that you eat okay is really made up of different organic molecules like you've already heard this I'm sure like you've heard of carbohydrates and you've heard of proteins and lipids okay those are some good examples of organic molecules that you typically consumed as food okay the example given here is an is a monosaccharide the simplest carbohydrate that is broken down in your body so when you eat pasta and bread and potatoes so those are all complex carbohydrates that's of no consequence to your to the cells within your body if that pasta and that bread cannot be broken down into the simplest building blocks of a carbohydrate which is what we call a monosaccharide there are three different types of monosaccharides one example shown here and this is glucose glucose is an example for monosaccharide given by this chemical formula molecular formula seasick h-12 o-6 so just broadly speaking when you take that glucose when glucose enters every cell in your body in the presence of oxygen which is right here the o2 okay that glucose is broken down into several different byproducts are carbon dioxide co2 water h2o and this ATP okay now that is where the chemical energy stored in this molecule namely glucose is transferred into this energy highly highly packed molecule packed with energy okay and this is called ATP ad machine triphosphate which we will talk about a little bit more in detail in chapter 3 okay but for right now I hope you understand the concept of chemical energy okay now electrical energy now you you've already seen examples of this in your everyday life so electricity this is an example of electrical energy this is actually the movement of charged particles which causes electrical energy okay mechanical energy is being something that allows involved in direct movement of matter like if you were pedaling on a bicycle okay radiant energy is a more broader spectrum of energy it kind of travels and waves and we've got different wavelengths in in this spectrum I like UV rays and x-rays and infrared rays and things like that visible light is something that we will discuss a little later on actually towards the end of the semester when we discuss special senses where we talk about how that visible light brings about vision in one of the special senses in your body namely the eye okay all right so let's move on and talk about I think I've already discussed this energy form conversions where every form of energy can be converted into a different form I like all of that electricity flowing through the the wires that all of that electrical energy allows it to be converted into light energy when you turn on that back switching you turn on the lamp okay now like I mentioned in my previous slide this conversion of energy is not efficient and some of it is lost as unusable energy which is typically lost as heat now I wouldn't think of it as a complete loss because really the heat that is generated every time you convert from one energy form to a different energy form in your body is not really lost because that heat is good because it helps to maintain the core body temperature right which is you need to have a certain sustainable core body temperature for you to exist and for you to for any living organism to to exist okay so now that we talked about energy forms let's quickly discuss what makes up matter okay if you keep breaking this down even further matter is made up of simple units if you will which is called an element okay now there are many elements that that are found in nature and this is all kind of described in you've probably heard of this if you've taken a chemistry class right periodic table okay there's about 118 elements in the periodic table that are organized in different rows and you kind of read those elements from left to right and they basically go from small to large as you go across the rows okay now you are not expected to memorize the periodic table this is a and B not a chemistry class but we will be focusing for the purposes of a and P will be focusing on a few important elements okay and some of them are listed here okay carbon oxygen hydrogen and nitrogen now it comes up in a subsequent slide but I'll go ahead and discuss it right here every element is designated by an atomic symbol which typically is the first letter or the first two letters of the name of that element so that's why you see carbon designated as see right the first letter see oxygen first letter Oh so the atomic symbol is all hydrogen H nitrogen n now there are other elements so really for air for the purpose of this lecture and for this class we will focus quite a bit on carbon oxygen hydrogen and nitrogen okay now we will also talk about other elements that are relevant to physiological processes in your body and some of those elements would be calcium okay which is designated CA now notice this sodium should have been an S or an S ol but it isn't because it is designated after the the Greek name which is natrium na and then you've got potassium which is designated K and then iron is designated Fe now we'll talk a little bit about some of these elements a little later on in a subsequent slide but I just want you to understand that these elements so every element has its own unique properties which consist of physical properties like smell taste texture things like that and chemical properties and this the chemical properties is what we need to be focusing on for this lecture which is how how do atoms within an element of carbon how do they interact with each other and with other atoms of a different element and that's that's really the whole concept of chemical bonds which we need to discuss as we go forward now every element is made up of basic building blocks called atoms and um so let's let's talk about what you would expect to see her than an atom okay so atoms within a particular element they all have the same physical and the same chemical properties but atoms of a different element will have different physical or chemical properties so atoms of carbon atoms all of them all atoms within carbon they all share the same properties but atoms within hydrogen or nitrogen will have different properties from those of correct okay so the smallest particles often element is called an atom and we've already talked about this right every element is designated by an atomic symbol and I gave you some examples in the previous slide where carbons designated see nitrogen and hydrogen age so on and so forth okay here are the four most important elements that you would see in your body okay nine 6.1% is made up of these four elements so you absolutely need to know this okay so we've got carbon hydrogen oxygen and nitrogen making up 96% of the entire body okay within the within the cells and we will talk about each of these important elements as we go along really focusing quite a bit on carbon okay right here because carbon is the molecule the element that's important in most of your biochemical molecules especially organic molecules and the organic molecules that we will discuss in a subsequent lecture would be carbohydrates lipids proteins and suddenly nucleic acids like DNA and RNA okay all right so the remaining well the remainder of your body which is about 3.9 percent this is made up of nine other elements like the ones listed here I'm gonna go over a few of these with you okay so we already talked I think a little bit about calcium calcium definitely important for muscle contraction especially cardiac muscle contraction like I said for the entire cardiac muscle to work as a unit count see'em needs to move from one muscle cell to the next monster said of the next to the next so that it all gets the same memo and it knows when to contract together okay calcium's also important in conduction of nerve impulses so the nervous system consists of fundamental cells or the most important cells called neurons and neurons also work by electrical signals but that's all guided by movement of ions across its cell membrane sodium and potassium being some of those important ones but also calcium okay calcium you're gonna see in bones and teeth as well so when we discuss the skeletal system will talk about calcium and in association with calcium phosphorus okay so calcium phosphates which is the most important inorganic compounds that you would see in stored within bones and an teeth can now sodium and potassium are worth mentioning as well because when we get to development of action potentials and how how when we discuss skeletal muscle physiology and then we move on and talk about neuron physiology it's really the movement of these two ions sodium and potassium across the cell membrane that will bring about the the creation of basically a concept called action potential which allows skeletal muscle cells to contract okay and likewise files off these are these nerve impulses down neurons so there are channels in the plasma membrane of these cells which open up and when they open up and sodium comes into that cell it brings about a certain physiological process and likewise of different channels open up allowing potassium to leave the cell it brings about a different phase of that process but together they work in generating an electrical impulse or in bringing about skeletal muscle contraction so we definitely talk about sodium and fat a little later on okay chlorine we definitely discussed this because this is the most important negatively charged iron that you typically see in the in the fluid space that you see outside of cells the extracellular space iodine when we discuss the endocrine system especially and we start talking about the thyroid gland thyroid hormones are most mostly made up of a colloid structure Kaira globulin in association with iodine and of course iron on is a very important element that you see as part of hemoglobin hemoglobin is what you see within red blood cells or erythrocytes okay so the iron is the part that actually binds the oxygen and that's what allows for transport of oxygen in your red blood cells as it is transported through the cardiovascular system to the different parts of your body to deliver that oxygen for all of the like processes that's required at the cellular level so these are the other the other nine elements that make up the rest of your body mass so carbon hydrogen nitrogen and oxygen make up 96 percent and then these nine elements here make up the remainder about four percent of your body mass okay okay so this is where we're gonna start talking a little bit more about atomic structure and start breaking it down even further okay so we said we've got all of these different elements right and like for example carbon and hydrogen and so on and so forth each element is made up of these building blocks so these major structural units called an atom okay so what happens inside of an atom okay we're gonna break this down even further and talk about sub atomic particles like these three guys right here protons neutrons and electrons okay alright so when you're looking at an atom okay there's a central part to the atom which is called a nucleus and inside of the nucleus there are two subatomic particles that are typically found you've got the protons and the neutrons and outside of this nucleus in these so-called orbits or shells that's where you will see all of these electrons which is also another subatomic particle so you've got three subatomic particles protons neutrons and electrons okay where would you see the new where would you see the protons and the neutrons only inside the nucleus but the electrons designated by these purple dots are the ones that kind of orbit or they kind of spin around outside of the nucleus okay now each of these subatomic particles has a certain amount of mass and it also carries a charge to it okay so protons are designated P lowercase B and notice it has a plus sign which means it carries a positive charge every proton has a positive charge okay now neutrons they're neutral so therefore they're designated with a zero which means no charge it's not positive it's not negative okay now electrons I'll write the opposite of the protons right they carry the negative charge all right so your protons with the positive charge and the neutrons with the neutral zero charge are the ones that you would see inside the nucleus and then outside the nucleus in these shells called orbits or orbitals I'll explain that to you in just a little bit these electrons are seen on the outside can they carry the negative charge okay so P plus and zero if you look and E minus again so those are your three subatomic particles that you will see inside of every atom which may which makes up an element okay I've already talked to you about this about the charges now in terms of mass okay the probe each proton carries a mass of one atomic mass unit and neutrons also carry a mass of one atomic mass unit so let me back up so remember the protons and the neutrons were located inside the nucleus these actually carry the most mass the entire atom which means the entire mass the density the density of that entire atom is located inside of the nucleus there is the electrons on the other hand the ones that carry the negative charge they have a very very small amount of mass about 1 mm of the mass that's carried by a proton or a neutron so therefore for all practical purposes you would kind of think of the electrons as the ones that carry the negative charge but they pretty much don't have much mass to it so again the bulk of the atom is within the nucleus there is the electrons they just spin around the nucleus quite freely and the partnerships that these electrons form with other electrons from a different atom of maybe the same element or a different element is what's going to contribute to bonding okay and we'll talk about the different types of bonds in just a little bit so we talked about that and electrons we just said yeah they carry the negative charge and they have a very miniscule amount of mass you know 1 mm the mass of the proton okay so now that we've talked about subatomic particles and what mass do they carry what charges do they bear and of course where are they located inside the nuclei inside of the atom the next thing I want to talk about is how an atom for all practical purposes is considered electrically neutral so what do I mean by that the number of positive charges namely the number of positively charged protons sorry back up should always equal the number of negatively charged electrons in an atom that is electrically neutral so what this means is that these positive charges will cancel out or balance these negative charges so the positives and the negatives they kind of cancel out each other therefore assuming this neutral condition of an atom okay so number of positive charges are balanced out for the number of negatively charged Chuck negatively charged electrons and therefore atoms are electrically neutral okay okay so at this point let's go ahead and get started with our discussion on what are the most important models of an of an atom and we're going to discuss the planetary model and the orbital model and I think I'm going to use a picture to kind of explain the differences between these two models here's a side-by-side comparison of the planetary model that you see here on the left and the orbital model on the right but this is off the same atom and this in this particular case what's depicted here is a helium atom so let's start with the left and then kind of compare what it looks like on the right okay so for a helium atom okay remember every atom consists of three subatomic particles protons neutrons and electrons right now for this helium atom there are two protons protons are designated by the by the red the neutrons are designated in yellow and the gray black is the electrons okay so in this helium atom okay the two protons and the two neutrons okay remember protons and neutrons are located inside of the nucleus so that's kind of where you see it located right now remember every atom is electrically neutral we talked about that on the previous slide so what is it what does that mean it means that the number of positively charged protons should always equal the number of negatively charged electrons right so if this helium atom has two protons well well to balance that I've got the two electrons in the shell or the orbit surrounding the nucleus so that's an example of the planetary model depiction of this particular helium atom Ken now if you would have explained this with the orbital model okay now how the planetary model works is that you are assuming that these electrons are spinning or moving around the nucleus in a very very fixed trajectory or a path called the orbit or the shell which is not technically correct okay this is a simplified view of how an atom is designated and where are the subatomic particles but in reality you cannot depict with with certainty exactly where the electrons would be found outside the nucleus okay you can only if you will come up with a probability of where you would expect where the electrons would most likely be okay and that's why the orbital model is more accurate although it's a little easier to picture the subatomic particles with the planetary model so with the orbital model everything is the same in the nucleus so you've got the two protons here and read the two neutrons in yellow okay but instead of depicting the electrons in a fixed path what you see right here is just this cloudy haze surrounding the nucleus and so that's now not an orbit that's an orbital meaning somewhere in this cloud right you would expect to see these two electrons but you don't know exactly where it is located around the nucleus so that's the only difference okay um planetary was the orbital model but other than that I mean if you're looking at any individual atom it's the same atomic subatomic particles okay protons neutrons and electrons so for the purposes of this lecture I'm going to mostly discuss chemical bonds using the planetary model because this way I can keep track of the electrons and where they are and if they were to leave that atom and jump over whatever you in this will all make sense as we get a little further on in our discussion but if it were to move if it were to be lost or if you were to gain an electron you could keep track of exactly the right numbers okay so we're going to be using the planetary model for the rest of our discussion okay so how do you identify elements so every element consists of atoms right atoms with their own physical and chemical properties and if every atom had three simple subatomic particles like protons neutrons and electrons well then how is carbon a difference from hydrogen and why is that different from nitrogen or calcium or sodium okay so if everybody has the same three basic subatomic particles why are they different right how do you identify one element how do you how do you tell it apart from a different element and that's the next part that we need to need to discuss okay so every element has the same three subatomic particles namely protons neutrons and electrons except they have very numbers of those subatomic particles okay so if you're looking at the periodic table which is I believe appendix II at the back of your textbook towards the very end you look at at that periodic table you will see all of the elements organized as you know different rows and if you're going from left to right you're gonna see you're gonna start with the smallest and then you're gonna keep working towards larger and larger elements and the reason they become larger is because you have a greater number of those subatomic particles within those elements within the atoms of those elements does that make sense so if you're looking at the most basic element there's the simplest element in the periodic table that's hydrogen hydrogen has one proton and to remember a hydrogen atom any atom is electrically neutral so if I have one proton then that should be balanced out by that one electron okay and then as you go higher and higher so if helium is the second element notice it's got a higher number of subatomic particles and then if you go to lithium which is your third element in the in the periodic table well you've got a higher number so let's look at this with the planetary model of each of these atoms right so let's start with hydrogen here on the left again protons designated red Neutron and yellow and electron in that gray so hydrogen has one proton in the nucleus and there's no yellow which means no neutrons right and since hydrogen is electrically neutral that one proton is balanced out by that one electron in the shell or that orbit around the nucleus okay now if you go to this atom here in the middle which is helium okay notice we went from one proton to what two protons okay and it so happens that this element also has two neutrons right and to balance the two protons I've got two electrons so obviously this is a larger element than this hydrogen element okay and then if you're looking on the far right here lithium lithium is even bigger than helium and hydrogen right and what's the difference here lithium has three protons it's got the four neutrons and to match the auto balance of the three protons I've got the three electrons so what you're seeing here going from left to right is an increasing number of protons right so in the case of hydrogen one proton helium two and lithium three and so on and so forth so as you go across the periodic table you're going to see an increasing number of protons okay in a step by step increase to match the the protons you always have an equivalent number of electrons and you may have either the same number or a slightly larger number of neutrons okay and that's how you identify different elements what makes up an element at the subatomic level is the same it's just varying numbers of those sub atomic elements sub atomic particles all right so I think that hopefully made sense continuing on with our discussion of identification of elements let's define two important terms here atomic number and mass number so the number of atoms within within an element or within an atom is given by the atomic number which is written as a subscript towards the lower left so Li stands for lithium let me back up which is the same as this atom right here yeah this is lithium so let me come back here so this is an atom of lithium it says has an atomic number three which means this tells me how many protons lithium has okay if I know the number of protons remember lithium or any other atom is electrically neutral which means if I know the number of protons I should also know the number of electrons it's the same okay now the mass number though is written as a superscript on the top left okay then okay so the mass number is a sum of the protons and the neutrons that exist inside the nucleus of that atom so I'm gonna give you an example here again the same lithium so if i have lithium designated as three on the bottom here you know that that's the atomic number and seven on the top there that tells me that that's the mass number of lithium if I know the atomic and the and the mass number of a particular atom I should be able to determine how many protons electrons and neutrons are present inside of that atom okay so let's let's get started here so atomic number is given by this subscript on the lower left so atomic number is defined as the number of protons which is three in this case and because lithium is electrically neutral you know that the number of protons should also equal the number of electrons so therefore I have three protons and to match those three protons I have three electrons I hope that make sense now the mass number like I said was sum of protons and neutrons in this case mass number for lithium is seven so seven is the sum of protons and neutrons but protons is given by the atomic number right okay so if I plug that three in there can I not find out how many neutrons are within this particular lithium atom I can that's nothing but seven minus three and your four right there so given the atomic and the mass number you should be able to identify how many protons electrons and neutrons exist in that atom that's a question you could expect on an exam and it's just basically your understanding of what's an atomic number was it what's mass number for that particular atom okay now that we've discussed atomic and mass numbers let's continue on with our discussion of a few more concepts here okay like isotopes an atomic weight so isotopes is these are structural variations or arrangements of the same atom okay like for example hydrogen if you recall from one of those previous slides we said it had one proton and one electron okay so this is one isotope of hydrogen called hydrogen right there okay and these two here are structural variations of the same hydrogen atom okay now I'm gonna I'm gonna walk you through these three variations again from left to right and then we will talk about how are they different and why they call isotopes okay so we said hydrogen has one proton and one electron to balance it no neutrons right okay look at your terraeum which is an isotope of hydrogen it's a variation of the same hydrogen isotope okay if you're looking at this okay it still has the one proton and of course we have that one proton you're gonna balance it out with that one electron but what has changed I've got a neutron now okay now let's look at tritium on the far right okay what is what what has not changed the same one proton you back up sorry the same one proton that you see in all of the isotopes in other words isotopes of the same element have the same atomic number okay the only thing that has changed is the number of neutrons in those structural variations in other words the mass numbers are different but the atomic numbers are the same between isotopes of the same element okay so many elements will have different isotopes are different and figurations of that basic atomic configuration okay and I'll give you some examples on the next slide before leaving this slide I want to talk about atomic weight so atomic weight is the average of the mass numbers considering all of the different isotopes of that particular atom so I know that there are three isotopes here hydrogen deuterium and tritium right if I were to take the mass numbers of each of these and I remember mass number is going to change right here the mass number is going to be what's mass number mass number number of protons and neutrons right so in this case mass numbers one here the mass numbers two right and in tritium it's three if you were to take an average of these mass numbers but you have to keep in mind the relative amounts of each of these isotopes so if I had said thousand isotopes of hydrogen but only say hundred isotopes of deuterium and ten isotopes of tritium you have to take an average of the mass numbers but keeping in mind the individual numbers of those isotopes if you do the math on that you calculate the average of all of those mass members for each of those isotopes you get the atomic weight okay now I'm not gonna have you do any of those calculations on an exam I just want you to understand the concept okay alright so now that we talked about isotopes what out Radio isotopes okay this is this is really important and it is relevant to clinical medicine okay both for diagnostic and therapeutic purposes so when you're thinking about isotopes and hydrogen is a very small element but as you go larger and larger and larger across the periodic table as they become bigger right they're the isotopes of larger elements they are unstable okay these heavier isotopes they tend to kind of decompose they tend to break down into no stable forms and when they break down literally they do they actually then they break down and the smaller I'll set up sod into smaller forms when they do that they emit certain rays like gamma rays and alpha and beta rays and basically all of this this this decay of material is what we called radioactivity which is somewhat parallel till you think of think about it as a tiny little explosion that occurs okay and I'm not gonna go into too much of the chemistry here but what I want you to understand is why is this valuable to a and B okay and basically we're thinking about how would Radio isotopes be valuable in research and in clinical medicine and so I'm going to give you some examples and I think the next slide does a pretty good job of it okay so here are some different Radio isotopes radioactive isotopes that are used in medicine cobalt-60 iodine-131 carbon-14 so on and so forth Technium 99 that's a very important one as well and it gives you the applications of all of these isotopes in medicine I'm gonna let you read over this this is not really gonna be on your exam but I want you to understand and appreciate the value of Radio isotopes in clinical medicine I'm gonna give you an example here with this cartoon schematic here on the bottom okay if you cobalt-60 is used as a radioisotope mostly in chemotherapy radiation therapy so if you had okay if there was a tumor that you wanted to destroy you wanted to destroy the cells within that tumor you would hit it with this radioactive source namely cobalt-60 as an example and what happens is when that when that radioactive isotope decays spontaneously it's going to emit radiation those gamma rays right and those gamma rays are toxic and they will kill the cells that are exposed to that radioactivity okay so this is a good treatment modality to treat cancer or tumors okay that's an example of one use in medicine it can also be used as well other radioisotopes could be used as tracers they can be used to like for example sodium this is used to study blood circulation so if you inject intravenously this tracer into your blood stream you can follow the path of this tracer and you'll be able to to see circulation patterns inside of your body and what advantage would that have and looking for obstruction so that if you can find out if there was any obstructed blood vessels which obviously is not good because that would reduce oxygen delivery so that's one way there so that's more a diagnostic tool there is in the case that you see here on the bottom with this schematic that's more of a therapeutic tool so it can be used for both diagnostic and therapeutic purposes in the clinic okay all right so now that we've talked about atoms I want to quickly discuss kind of build a little bit more on these concepts and discuss what's a molecule versus a compound okay so let's go ahead and give you some examples here a molecule when two or more atoms of the same element form a chemical relationship with each other it's called a molecule so for example in this case this is a this is hydrogen this is two atoms of hydrogen forming hydrogen h2 okay or two atoms of oxygen forming oxygen oxygen gas o2 okay so as you can see here if it's too similar atoms of the same element it's a molecule whereas in these examples here ch4 for methane we talked about this you know previous slide c6 h-12 o-6 which is glucose and in this case water h2o all of these let's look at water this is basically two atoms of hydrogen forming a chemical relationship a bonded relationship with oxygen so therefore these are atoms of different elements forming a chemical bond and therefore these are examples of a compound whereas if it's ad of the same element then it's called a molecule okay now how these bonds formed the hats way we're leading into next okay you need to talk about ionic bonds and covalent bonds and then of course what's a hydrogen bond okay okay so let's keep going ahead before we start our discussing about chemical bonds I want to quickly mention mixtures okay a mixture is basically where two or more components are physically interacting with each other they're just they are mixed together in the same vicinity or in the same environment but they don't really exchange electrons there's no chemical relationship between them they're only it's only a physical interaction and there's three different types of mixtures solutions colloids and suspensions and I'm gonna use the next slide to kind of go over the differences between them but very quickly a solution is basically one that contains two main components the majority of the solution is the liquid component called a solvent in the body there are the most important solvent in the body is water h2o okay now dissolved in that solvent or suspended in that solvent is the minority component of that solution which is called a solute like ions and like glucose and and other other things that you typically see within within a solution okay the example given here is okay if glucose is dissolved in blood well glucose would be the solute part of it it is dissolved or suspended in blood blood being the solvent blood has different components to it but the majority part of blood is basically water about 55% of it is water okay okay then there are other two types of mixtures which are called colloids and in suspensions and so bear with me I'm going to actually use the next slide to explain all three mixtures and there and kind of compare them one to the other so like I said a solution is it consists of two main components the majority being are the solvent which in this case we looking at it is water and solutes are the minority part of that solution which are suspended in that in that solvent now the solute particles in a solution are very very very tiny okay they will not settle down they are uniformly suspended in that so in that solution they don't scatter out light a colloid on the other hand you compare these solute particles the ones that you see here they get a little bigger okay so they're slightly larger but they still are not large enough to settle down okay but they can if you shine light through it they can scatter light through that beaker of a colloid okay the cool thing about a colloid is this concept called Sol gel transformation so where it can go okay as you can see in the example of a colloid that you are aware of in your everyday life is jello okay everybody knows what that's all about so it first starts off in a fluid state right and that fluid state is called Saul okay and then if you take that fluid right and put it in the fridge it's going to set it's going to form more of a solid or semi-solid kind of a state which is more of a gelatinous phase that's why it's called the gel phase okay so that's where you go from this the fluid state to the solid state the sol-gel transformation and what happens if you take that jello out of the fridge and again let it kind of just sit out at warmer temperatures for a longer amount of time it's going to then transform back into the fluid state so I can go back and forth between the soil state and the gel state now why are we talking about this in the body okay there are many examples of colloids that you would see the biggest example is within every cell of your body okay so every cell has this outer boundary called the plasma membrane but inside of it is this colloid material called the cytosol or the cytoplasm and it's within the cytoplasm within this colloid material that you've got other organelles like the mitochondria and the Golgi the endoplasmic reticulum the lysosome all of those organizer that gelatinous kind of a colloid called the cytosol within the cells and what it does by the fact that it has this soil gel transformation ability it has a little bit of fluidity to it so it's not a very rigid structure it allows cells to change shape okay which is great when cells have to like for example contract and relax also plays a huge role in processes like mitosis which is where one parent cell divides into two daughter cells in order for that division to occur there's got to be some fluidity to that cell to allow that one cell to divide into two cells so it can't be a very rigid structure and that's why we talk about colloids here because that's a good example of what you would see in the body at the cellular level okay now if you go to the far right this is a suspension this is where the solid particles become really really large and if you give it time those solid particles will settle to the bottom okay a good example of a suspension in the body is blood okay okay blood consists of different components it has a liquid component which is plasma okay which is about 35% of the entire blood the composition of blood and then suspended in this liquid plasma is the cellular component which is all of your RBC's and WBC's platelets and and other molecules that are suspended in that liquid part so so a blood is an example of a suspension because if you take a vial of blood and you let it sit for a while okay hours or you can speed up this process by spinning it down in a high-speed centrifuge what happens then is you see a separation of these components the liquid part obviously being lighter is going to go to the top and the heavier components the sales and everything will settle to the bottom because you see a separation like this this is called a suspension okay so I want you to keep in mind these are all examples of mixtures solutions colloids and suspensions and they're all three different types of mixture examples of varieties are seen in your body like solution so you're gonna see water and other solutions throughout your body inside the cell outside the cell all the time I give you an example of a colloid and I also give you an example of a suspension so these are all examples of mixtures now what I want you to remember is that there is no chemical interaction between the components of a colloid or the components of officers function is there's no real chemical interaction between the liquid plasma and the red blood cells for example right all it is is that it's a physical mixing or an interaction between all those components and that's why this is called a mixture instead of it being actually a chemical bond and being a compound okay all right so I think I've gone over the different mixture varieties let's see what's the next slide yeah okay so this gives you an example but the difference between a mixture in a compound so again want to reiterate a mixture it's only a physical interaction between the different components that's why they can be separated out again they can be strained out it'll be filter and so on and so forth there is no chemical bonding now a compound right like c6 h-12 o-6 which is glucose or water h2o all of those are actually that's a chemical bond between atoms of either the same element or the or different elements that forms a compound so that's a chemical bond that is not just a physical interaction which is where this discussion is leading next what are the different compounds and how do you form compounds what are the different types of bonds and so that's what I'm going to discuss next as we move on further in the rushon of these lights okay all right you guys this is where it gets interesting okay we're gonna start talking about chemical relationships which are energy relationships okay now do y'all remember we talked about an atom just awhile ago we talked about what makes up an atom we discussed different subatomic particles protons neutrons and electrons okay when I talk about an atom interacting with another atom then it's this this is where you have a chemical bond that's formed these are energy relationships it does not involve a proton and it does not involve a neutron now if you remember where are those protons and neutrons located right here in the middle in the nucleus right these guys they do not participate in a chemical bond babe hold their ground and they sit happy inside of the nucleus okay they don't move in an atom okay how are chemical bonds formed between one atom and another it's these other guys namely the electrons that you remember they seen in the orbit or if you're talking about the planetary model or the orbital if you're discussing the orbital model okay again for all practical purposes for the simplicity of this discussion I'm just going to discuss the planetary model okay so first things first chemical bonds are energy relationships that are formed only between electrons of different atoms or reacting atoms okay so remember we said there are different elements 118 elements in the periodic table and the as we go from left to right across those rows they become larger and larger because the number of protons the atomic number keeps increasing so therefore we're talking about all of these remember they are electrically neutral which means number of protons always equals number of electrons so where you going to place these electrons where exactly are they located yeah sure in the orbital I know that but again for simplicity let's assume the plan okay they are located in these shells or orbits around the nucleus so again I got my nucleus here in red okay and inside the nucleus I've got my positively charged protons and the neutral no charge right the neutral neutrons sitting inside the nucleus the electrons I said were not inside the negatives they are found outside the nucleus in these gray orbits that I've drawn out here for you and these are called shells or orbits this is where you see the electrons okay for this atom to interact chemically to form a bonded relationship with another atom it's these electrons in these shells that need to form in energy relationships or bonded relationships with other atoms okay so it's not the protons and it's not the neutrons that we are interested in when we do start discussion of our chemical bond concepts it's only the electrons okay so we as I was explaining just a while ago as you go to larger larger atoms you will have an increasing number of protons and therefore an increasing number of electrons where are these electrons placed there are several shells or locations around the nucleus okay so for I'm not gonna go into too much chemistry here I'm going to keep it as simplistically as I can just as long as I get the concepts across to you okay so each shell in this case n okay each shell is designated by a number so this this four shell that is closest to the nucleus is shell number one and then you got my second shell here which is the shell outer outside of shell number one and of course I've got shell number three on the outside and then you've got four five so on and so forth okay as you go into larger atoms good larger elements okay so shell number one is the closest shell closest to the nucleus okay and then you it goes in increasing numbers as you go outwards now every shell has a maximum number of electrons that it can hold and you're gonna need to know this so again I'm not gonna have you draw out anything on an exam I just want you to understand the concepts okay for the first shell it can only hold a maximum number of two electrons okay so max electrons two for the first shell the second shell can hold it has a maximum capacity of eight electrons the third shell can hold 18 electrons and so as you can kind of get the picture here the further out you go away from the nucleus the more number of electrons that that shell can hold or the maximum capacity increases as you go out further and further outside of the nucleus okay so remember it's the electrons that form energy relationships which are called chemical bonds okay so we're gonna have to define which of these electrons are capable of movement okay so in that regard we're going to talk about what's about valence shell so the electrons in the outermost shell or the orbit that surrounds that nucleus the outermost shell is called the valence shell okay this is the shell that has the most amount of energy in it and these are the these are the electrons that are most likely to form any kind of chemical bond with a different atom in other words the electrons in the valence shell are the most chemically reactive electrons can you kind of think about it this way remember the protons with their positive charge are in the nucleus the first shell here has two electrons right the closer these electrons are to the nucleus they are attracted or they're pulled closer towards the nucleus because of these positively charged neutrons so you can imagine the further away you go from the nucleus those electrons would more than likely be the troublemakers okay there that's why they are the most chemically reactive electrons okay now if you're talking about the smaller elements which only have one shell or maybe two shells well the if if an element has only one shell while those two will electrons in that one shell are is the valence shell and yes they will be chemically reacted but the further away you go the more they those electrons become less tied to the nucleus and they become more chemically reactive bottom line is this for any atom regardless of the size of the atom the outermost shell is always called the valence shell and these are the electrons that we want to be watching the most okay and this is where I'm going to introduce the concept of the octet rule hopefully yeah that's right okay so remember I said the valence shell is the outermost shell within an atom okay when the valence shell is not full it does not have it does not satisfy something called an octet rule and I'll get to that when this valence shell is not full this is what makes it a reactive element okay so the overall driving force behind any chemical bond is the desire for that valence shell to satisfy octet rule octet is a rule of eighths okay so what does that mean okay remember we just said on the previous slide the first shell can hold a maximum of two electrons the second shell can hold eight electrons and the third shope and hold 18 electrons and so on and so forth right so octet rule says okay as long as a shell satisfies altitude which is as long as it has eight electrons it's a stable shell okay except the four she'll remember the first shell can only hold two electrons so therefore it is stable if it has those two electrons it cannot hold anything more so it is stable at two but any other shell shout number two three four five whatever if it has at least eight electrons it satisfies the rule of AIDS or octet rule and therefore is a stable shell okay so what you want to see for any atom is look at the outermost shell the valence shell okay does it satisfy octant row so if it's shell number if it's if it's a atom that only has one shell well then that one shell is the valence shell as long as it has as my pointer as long as it has the two electrons it satisfies octet rule if it's any atom that has more than one shell so if it has two three four five how many ever shells look at the outermost shell right as long as it has at least eight electrons it's a stable shell okay so any valence shell that is not full in other words does not satisfy the rule of eight becomes a reactive element okay so the number of electrons participating in bonding is always limited to the rule of eight regardless of capacity 18 or higher okay so I'm gonna give you an example of summing some elements in just a little bit so this kind of solidifies what we've just talked about so so except shell number one remember the capacity for shell number one is a maximum of two electrons right so if it has two electrons in shell number one it satisfies the octet rule but any other shell accept shell number one all other shells if it has eight electrons it satisfies octet rule if it has anything less than eight it becomes a troublemaker and those electrons become chemically reactive in that valence shell okay so let's give some examples here are some really good examples of chemically reactive elements let's walk through all these scenarios let's start with hydrogen here on the top left okay now you know you do not need to memorize any of these numbers or what is the atomic number and all you don't need to know that as long as you understand the concept okay okay so for hydrogen the atomic number is one okay so I'm gonna see my proton here inside the nucleus but you don't have to worry about that remember protons do not contribute to electron relationship and two energy relationships they don't contribute to bonds but we need to keep our eyes on is basically the electrons so hydrogen has that one electron okay so which means this is shell number one correct it's a closer shell to the nucleus it can hold a maximum of two electrons but how many do I have here only one does it satisfy octet rule no it does not because for that first shell I need to have at least two in order for this valence shell to be stable if not it is chemically reactive okay so let's look at the second example here carbon carbon has an atomic number of six so I've got six electrons to match those six protons so my first shell which is right here can only hold a maximum of two electrons so that's right so I'm going to put the first two electrons in there which leaves me with what if I have a total of six and I place two in the first shell it leaves me with one two three four in the second shell right now remember the outermost shell is the valence shell so this is show number two this is the outermost valence shell how many electrons does it need to satisfy octet rule rule of eights says it has to have at least eight electrons how many does carbon have how many valence electrons does it happen only has four therefore it does not satisfy octet rule and this is another this is a reason why carbon is considered chemically reactive okay now if you remember it's only these valence these four electrons that are reactive and are capable of partnerships with other atoms and I'll give you examples as we go along okay let's look at oxygen right quick now the example for chemically reactive element it has atomic number eight so I've got my two electrons right here in the very first shell you see that for shell right there okay that's the inner Michelle here's my shell number two so if I have two in the first shell I have basically six remaining in that second show right now these six valence electrons do not satisfy octet rule because octet rule says I need at least eight to be stable so therefore these six valence electrons will be the troublemakers for this oxygen atom okay they will be the chemically reactive electrons for that error let's look at sodium this is getting a little bigger sodium has an atomic number eleven okay so I've got two in my first shell right here okay here's the second shell now remember the second shell has a capacity of only eight so therefore it will fit the next eight so the eight plus the two equals ten which leaves me with only one electron in that third shell right now the third shell the outermost shell in this case is the valence shell now to satisfy octet rule this valence shell needs at least eight what do I have sodium only has one valence electron does that satisfy octet rule no it does not this is a this is a reason why sodium is chemically reactive as well okay so these are all four really good examples of chemically reactive elements but you're looking at is the valence shell you're looking to see if the valence shell has enough electrons basically eight electrons to satisfy octet rule with the exception being if you're talking about the valence shell being shell number one where can only hold two so it is stable it satisfies our control if it has two electrons okay so if those are chemically reactive elements then what are chemically inert elements okay chemically in our element is a is one where the valence shell is fully occupied which means it has the eight electrons to satisfy octet rule okay so let's go ahead and look at these two examples here helium on the left and neon on the right okay in the case of helium atomic number two obviously you're gonna place those two electrons in the very first shell the innermost shell which happens to also be the outermost valence shell in this case right and since I've got the two electrons in the valence shell there's it cannot fit anymore it has a maximum capacity of two so it satisfies octet rule with those two electrons therefore helium is considered inert meaning these two valence electrons since they satisfied octet rule they cannot react with any other atom of a different element that's why these are chemically inert they are not capable of any atomic I'm sorry our chemical bonds can here's another example here on the right neon neon has an atomic number 10 so you know you're gonna place the first two electrons in that four shell leaving me with eight in the second shell right now the second shell the valence shell satisfies our to true because I have eight electrons so because it satisfies after drew these eight valence electrons are not going anywhere they will not form a chemical bond they will not form any chemical relationship with any other that this is why you've got these two examples of helium and neon because its valence shell satisfies octet rule that's why these are called chemically inert elements okay so I think we have discussed some of these concepts which leads us to I guess the ideas of what is a chemical bond now okay so so you're you should understand by now that if the valence shell has anything less than eight electrons if it does not satisfy octet rule then those valence electrons become chemically reactive so what damage can they do well this is where it gets more fun this is where we start talking about how these chemically reactive electrons from one atom can form a partnership and energy relationship with an atom from a different element or an atom from the same element which is where we're leading to next which is different types of chemical bonds okay all right okay so here are the three different types of chemical bonds that we will discuss and again I'm gonna keep this as basic as I possibly can I just want you to understand the differences between these three bonds how they're formed and some of the major concepts related to chemical bonding okay so we're gonna start with ionic bonds first and then move on to disk in covalent bonds where we will talk about two different types of covalent bonds polar and nonpolar bonds and the last thing we will discuss is what's a hydrogen bond okay all right so ionic bonds all right I'm going to let you all read this light because it explains what's a negative charge on a positive charge I think I'm gonna go ahead and explain this using an example where we will discuss all of these concepts I'm gonna see this happen a lot when I'm lecturing either live or pre-recorded or whatever if there's a word slide I might skip over it because that's really an explanation for you as you are reviewing the material studying the material yourself at home or in groups however if there's a schematic involved I would much rather use that and to discuss all of the concepts related to that particular topic okay so here's an example of an ionic bond and I'll explain what's going on here okay you do not need to memorize any of this you will not be asked on your lecture exam to draw out any of this or give me an example of how sodium chloride is formed and why is it an ionic bond no you're not gonna be asked any of that all of the lecture exam questions are multiple-choice so the answer is there in front of you it's mostly for you to understand concepts okay so I'm gonna give you an example of an ionic bond in this case we've got sodium atom and chlorine atom okay and you do not need to memorize atomic numbers and all of that that's not required either I just want you to understand how is an ionic bond formed okay all right so let's start with sodium here on the left and then chlorine on the right when I talk about a partnership write a chemical partnership an energy relationship between the electrons of this sodium atom and the electrons of this chlorine atom okay and when there's an energy relationship between these two atoms it forms an ionic bond and my what I'm leading towards is why is it an i and why is it not called a covalent bond okay so I need you to understand ionic bonding first so let's start with sodium you got to remember everything that we've discussed so far which is you know how many atoms can fill each shell they all know the whole concept of octet rule and all of that all that's gonna be important you're gonna bring all of the pieces of that puzzle together now so that you see the bigger picture okay all right so sodium has an atomic number of 11 okay so what that means is that I've got these 11 protons situated here in the nucleus that you don't see but we don't have to worry about it because I said protons do not contribute to a chemical bond right but we need to keep in mind are the electrons now since sodium is electrically neutral we know that if there are 11 protons inside that nucleus well it's also got 11 electrons spinning out here in those orbits okay so all right we've established that sodium has 11 electrons how would they be distributed right you always fill the closest shell to the nucleus first before you fill the outer shell so you remember a while ago we said before shell can hold two electrons the second shell can hold what eight electrons and the third shell can hold what 18 electrons right and so on and so forth so now if I have a sodium atom with eleven electrons what happens to these elect to these eleven electrons where would they be placed well can you put them all in shell number three because I can hole 18 right in shell number three can you put all 11 and shell number three no no not so fast you always have to fill the innermost shell first and then you work outwards okay does that make sense so okay so if I have 11 electrons you would this kind of makes sense the first two will fill that in a more shell because maximum capacity for shell number one is only two okay I've got two electrons placed there which means I have to move outwards into the second shell what happens here second shell I can only hold eight maximum electrons so therefore I've got eight placed in that second shell so two in the first shell eight in the second shell which is a total of ten leaving me with just one electron in shell number three okay I hope that made sense to you so I've got one electron in the atom oh sure now what is that outermost shell called valence shell remember that part okay now always look at the valence shell and ask yourself does it satisfy octet rule right so I've got my valence shell over here with only one lone electron how will it satisfy oxygen well if it had eight electrons well one is nowhere close to that eight electrons that's needed there for this valence electron is a reactive electron alright so we got that now let's look at what's going on what's the story with chlorine okay chlorine is slightly larger it has 17 atomic number 17 so I've got 17 protons here in the middle in the nucleus but to balance that out I've got 17 electrons same concept okay you always start filling from the innermost shell and what your where outwards so same thing two in the first shell I've got eight in the second shell so that's a plus two ten leaving me with seven here in this outer Moshe does that make sense okay so my outermost valence shell here has seven electrons in the case of this chlorine atom does it satisfy a little no it doesn't it absolutely does it means eight to satisfy octet rule so look at this situation I've got sodium with one valence electron and chlorine with seven valence electrons both of them are unstable both of them are reactive both of them are unhappy because they have reactive element reactive atoms valence add sorry reactive electrons so therefore if you're thinking about it okay look at sodium it has one valence electron so there's two different ways that sodium can satisfy octet rule okay one would be to gain seven more electrons because if it gained seven more plus the one that it has equals eight it would satisfy octet rule or the second option would be get rid of it one valence electron right does that make sense so two options I look in gain seven or can lose the one that it has and in both situations it would then satisfy optical because if I lose this one then I'm down to this in the second show where I have eight it satisfies artichoke it would make that sodium atom stable now if you're looking at chlorine right so same deal I've got seven valence electrons it's also unstable because it does not satisfy octet rule it means eight okay so if you're looking at these two atoms sodium it would make more sense for sodium to get rid of that one electron whereas in the case of chlorine because it has seven in order to satisfy octet rule if it gains that one electron from sodium it would have eight ten of its own and then satisfy octet rule so you've got a perfect partnership there okay sodium that has its one electron valence electron that it's willing to give away to lose and chlorine with its seven valence electron looking for one more which it would be willing to accept from sodium okay so in this partnership okay what happens is this one valence electron from sodium jumps over basically it is completely lost by sodium and that one electron from sodium that hopped over to chlorine is gained by chlorine so in this case I've got two partners sodium and chlorine two different atoms one that loses its electron and the in the other case the other one accepts that electron so we have a complete loss and a complete gain of electrons in the two atoms that are forming this chemical partnership and when that happens when there's a complete loss or a complete gain of electrons between the the bonding partners then that's when an ionic bond is formed okay so I want to continue on with this concept okay so let's talk about what happens when when sodium loses its one valence electron it's down to basically the two shells as you can see here the third shell is missing because it's lost that one electron so remember when it started off sodium had 11 protons right and to match it it had the 11 electrons but if it gave away one electron to chlorine well how much how many electrons then remain it's 10 electrons is this electrically neutral no it isn't electrically neutral would be where you have an equal number of protons and an equal number of electrons in this case I have one less electron then I do protons creating what so as you can look at if you're looking at it here you have 11 positive charges but you only have 10 negative charges and therefore this is no longer an electrically neutral atom it's instead now an ion io n ion because it has an unequal number it's unbalanced number of charges in this case I just created a positively charged ion why is it positively charged because it has one more positive charge in relation to the negative charges okay any positively charged ion is called carry on and he would designate in this case sodium since it became a positively charged cation he would designate it as na with a plus sign notice this wasn't this was just sodium it was just sodium atom but now it is a sodium ion because it gave away its valence electron does that make sense okay now let's look at what's going on with chlorine on the other hand okay so for chlorine I've got okay it gained that one electron so I still have my three shells here for chlorine except instead of seven valence electrons I have that eight electron that jumped over from sodium correct so I've got eight valence electrons so to begin with it had 17 protons and 17 electrons but since I gained that one from sodium now I have 18 electrons this is also not electrically neutral I have one additional negative charge in comparison with the positive charges that's why I designate this as a chloride CL chloride ion and as you can see it's a negative negatively charged ion why because it has one more negative charge compared to the positive charge okay and he negatively charged ion is called an anion and any positively charged ion is called a cation okay so what I just did is when sodium lost its valence electron to chlorine so chlorine lost its electron I'm sorry sodium lost its electron chlorine gained the electron as a result and formed positive and negatively charged ions right so now I have an na plus and a CL minus and because opposite of ly charged ions attract each other like the positive and the negative attract each other the sodium is attracted to the sodium ion is attracted to the chloride ion and that's where you form that ionic bond right there okay so therefore ne plus and Cl minus because of the the the change in the electrons right from the sodium to the to the chlorine now just formed an ionic compound in Asya okay so in essence an ionic bond is formed when when you have a complete loss or gain of electrons so this is a chemical partnership because of energy relationship between electrons valence electrons of in this case two different atoms resulting in a positively charged and a negatively charged ion and when those two ions come together it forms an ionic bond this in this case this is NaCl okay all right so most ionic compounds are salts and I'm going to continue with the example of NaCl okay so all of your sodium ions or any plus your positively charged cations are designated by the yellow structures and the negatively charged chloride ions are designated as green structures remember the the plus and the minus I attracted to each other so basically the sodium is attracted to the chloride ions and the chloride ions are obviously attracted to the sort of sodium ions so therefore they form this three-dimensional crystal like structure and that's why salt exists as crystals NaCl is an ionic compound which exists as a crystal okay so that in essence is how an ionic bond is formed what we're going to discuss next is move a move on to discuss covalent bonds so in an ionic bond you have a complete loss or gain of electrons between the bonding the partners the atomic partners right in the case of a covalent bond it's not a complete transfer of electrons it's not a loss it's not a gain it's not a transfer at all it is more of a shared concept okay so when you have sharing of of two or more valence electrons then you'll form a covalent bond and depending on how many electrons are being shared if it's just two electrons being shared then you have a single bond if it's four electrons it's a double bond if you have six electrons it's a triple bond okay so I'm gonna explain some examples here in just a little bit depending on how the sharing occurs if it is if those electrons are being shared equally between all the partners of that particular bond then if it's shared equally then you form a nonpolar covalent bond but if it is shared unequally then you form polarity you form a polar covalent bond and this will make sense when I give you some examples okay so let's start with the most simplistic example of a covalent bond and here you see in the example of a covalent molecule called methane ch4 and as you can see here this is one carbon atom and four different hydrogen atoms all coming together to form this one molecule or compound of methane okay so again structurally the designated of the here again you don't have to memorize any of this just understand the concept carbon here surrounded by the four hydrogen atoms carbon atomic number six I've got two in the first shell two electrons before shell about four valence electrons in the second shot okay this is my valence shell it's got four that's not the same as eight I need eight to satisfy octet rule so therefore carbon is electro chemically reactive likewise if you look at each one of those hydrogen atoms right it only has one electron in its valence shell remember that's the back shell number one if it has two it satisfies octet rule but it only has one therefore this is a chemically reactive atom okay now let's talk about how a partnership can be formed between this carbon atom and each of those four hydrogen atoms okay so what I'm gonna do here is look at the on the right here you see in the carbon right here in the middle and I've got the full hydrogen atom surrounding it okay so I'm gonna look at these innermost electrons right here one two three and four those are the four valence electrons of carbon and then look at each of these hydrogen's okay so I've got that one valence electron this is for this hydrogen atom here's the valence electron for the second and likewise a third and the fourth okay now what would make hydrogen happy well it needs to satisfy octet rule alright so if it has only one valence electron it will satisfy rule of eights if it has at least two right okay so what if let's look at this hydrogen atom okay so what if it has its own valence electron okay right over there what if it shared one electron from carbon right so in this case it has one of its own and one shared from carbon that equals two right two valence electrons well then this hydrogen atom would then be stable it would have satisfied the rule of eights or the octet rule likewise same story here with the second hydrogen right has one of its own and one shared from carbon and the same of the third the fort so each of these hydrogen atoms now satisfies octet rule because it has one of its own electrons and if it shares one from from carbon then it makes it to which satisfies octet rule for that shell number one okay so that's that's a good deal for hydrogen what about carbon well let's look at carbon carbon has four right of its own but what if it was sharing one valence electron from each of these four hydrogen atoms then it has four of its own plus four shared from four different hydrogen atoms four plus four equals eight so for that second shell if I had eight in that second shell it would satisfy octet rule so as you can see here in this unique relationship it doesn't make sense for carbon to give away all of its electrons or for hydrogen to do the same you-you it would make sense for them to share those electrons between each other don't give away anything let's just share what we have what I have with what you have does that make sense okay so what happened here is this hydrogen atom and the carbon atom formed basically one shared relationship here what am i sharing I'm sharing one of my own and one from the other atom so it's a pair of electrons that's being shared in this case so this sharing of one pair of electrons is basically a single covalent bond designated by a single solid line okay so structurally you can put the C in the middle for carbon and the four hydrogen's designated by H surrounding it and so when I look at that single line there it tells me okay between this carbon and that hydrogen atom there is one pair of shared electrons so that's why I see that single line okay likewise for the second the third and the fourth okay so you can kind of see it all around so that's a covalent bond it's not a complete transfer of electrons like we did in sodium with in the case of the sodium fluoride this is a sharing of alike okay now I want to go one step further these electrons are shared equally meaning it's not like the hydrogen or the carbon is pulling those shared electrons closer to itself you can almost imagine those shared pair of electrons being somewhere right down the middle between carbon and hydrogen if it if it helps you form a picture in your head if you if they were sharing it equally it's kind of somewhere right down the middle right it's not mine it's not yours its shared property but it's somewhere in the middle if you share equally then yes you form a covalent bond but it is it forms a nonpolar covalent molecule because everybody all the partners in this relationship are sharing those electrons equally okay so I'm going to go ahead and give you another example here well actually two more examples over here so we just talked about a single covalent bond so let me back up what's a single covalent bond it's sharing of one pair of electrons right so what is a double covalent bond if I share two pairs of electrons and a triple covalent bond would be three pairs of electrons okay so let's let's look at some examples again you don't have to draw out any of this in your exam you don't have to memorize it you just need to know what is a single covalent bond and why is that different from a double or a triple covalent bond okay so I'm not going to go into the electron configurations here y'all can look at it it's it's pretty similar to what we've been discussing so far but what I have here is two oxygen atoms okay bottom line is each oxygen atom has six valence electrons one two three four five six yeah correct so has six valence electrons and this guy here also has six valence electrons well none of them satisfied octet rule for that second shell to satisfy octet rule I'm going to need eight valence electrons correct but I only have six which means I'm gonna have to find two more okay so let's bring those two oxygen atoms closer together right there okay so let's look at the one on the left here if this oxygen has two of its own valence electrons but it shares two electrons from the an oxygen atom then it's got basically six of its own plus to share that equals eight satisfies octet rope so it's the same story for this second oxygen atom here - right so in this way this is a bonded relationship between two oxygen atoms but it was not a transfer of electrons no complete gain no complete loss it was a sharing of electrons and that's why it's a covalent bond and if you look closer we're sharing one and two pairs of electrons designated by a double solid line right there that's why this is a double covalent bond double solid line okay same story here with nitrogen whoops went too fast with nitrogen was sharing three one two three pairs of electrons between these two nitrogen atoms designated by three solid lines that's why this is a triple covalent bond okay so if if you're sharing one pair of electrons that forms a single covalent bond two pairs of electrons double covalent and three pairs of electrons triple covalent okay so let's now go ahead and discuss polar versus nonpolar covalent bonds okay I'm gonna give you an example here of let's see this is carbon dioxide co2 with carbons shown here in the middle in black and the two oxygen atoms shown here on the left on the right this is imprint okay so structurally designated by this formula right here so carbon in the middle and the two oxygen atoms on either side now without even knowing atomic numbers and and all of that you don't even need to know all of that just look at this the structure right here and it tells you the entire story because this tells me okay between this carbon and that oxygen I see two solid lines which means that's a double covalent bond so what does that mean it means that there are two pairs of electrons being shared between this carbon and that oxygen on the left and likewise there's two more pairs of electrons being shared between the same carbon but a second oxygen atom right okay now this sharing of electrons is a equal sharing so between this oxygen and the carbon these two pairs are shared equally between the second oxygen and the carbon again you've got two more pairs that are shared equally if you have equal sharing of electrons okay it does not create polar ends and this will make sense when I talk about water next when you have equal sharing of electrons it doesn't create polarity and therefore if there is no polarity it forms a non polar covalent molecule okay I'm gonna give you an example of water here next because that's a great example of a polar covalent bond or a polar covalent molecule okay a polar molecule is also called a dipole okay and I'm gonna give you some examples this is often seen when you have topless ships being formed between atoms especially that are considered more electronegative what's that mean okay that means if I have an atom where the valence shell has six or seven electrons they tend to be more if you will if I have only six or seven valence electrons I tend to or I already want one or two more so I tend to be more electron hungry or electron greedy like oxygen that's a great example of electronegative atom because it has six valence electrons and it tends to pull those shared electrons closer to it to itself there's other electrons I'm sorry other atoms that have only one or two valence electrons are more electropositive like hydrogen they tend to like I'll give away my shared Allah even though chair I'll let you have it a little closer to yourself that's something like that okay so I'm going to give you an example of water and hopefully this makes some sense here let's see so this is an example of a polar molecule in this molecule of water designated as h2o what this tells me is that I've got one oxygen atom and two hydrogen atoms okay so the the oxygen is depicted in red over here and here are the two blue which are the hydrogen atoms okay so structurally designated like this okay so what this tells me is that the oxygen and this first hydrogen forms a single covalent bond meaning it shares one pair of electrons and then the oxygen with the second hydrogen atom forms shares a second pair of electrons so this is another covalent single covalent bond right okay if everybody was sharing their electrons equally okay if you can kind of imagine like two dots depicting two electrons right are one pair of electrons so if the two dots or the two electrons were right there in the middle and here's two other electrons right there in the middle then everybody would be happy will be a shared partnership that's equal except it isn't okay because what did I say in the previous slide oxygen is more electronegative meaning it is more electron hungry or greedy so here's the deal oxygen says to this first hydrogen atom okay I'm going to share my electron with you so we're gonna have a covalent partnership here except I'm gonna pull the shared pair of electrons closer to myself and it says the same thing to the second hydrogen atom right here so what essentially what happens is those pairs of electrons that are shared are closer to this oxygen atom than it is to the two hydrogen atoms of that molecule now what charge do electrons carry negative charge remember that okay so in this case since the shared pair of electrons are held closer to in the vicinity of that oxygen atom it assumes what we call a partial negative a Delta negative charge the negative is the is coming from the fact that it's pulling those shared electrons closer to itself that's why it's the Delta negative end of this entire molecule of water there's the two hydrogen atoms well they get the short end of the stick right they're still the still sharing but since the electrons are not closer to themselves it becomes the other end other polar end of this molecule therefore becomes Delta positive X so when you have a molecule that is covalently formed right because of sharing of electrons but you have unequal sharing of electrons then one end that has the electrons closer to itself becomes the negative the more the the partial negative end of the molecule and the other end becomes the more positive or the partial positive end of the molecule and because in now what I just did with this molecule is I created polarity it's like I created a negative and a positive end it's like creating a North Pole and a South Pole they are opposite axis that make sense since I've created polarity or a separation of charges ok this unequal sharing of electrons creates polarity and therefore this molecule because of unequal sharing is called a polar covalent molecule so I hope that made sense to you ok in the case of methane that we discussed a while ago the ch4 everybody shared equally so therefore it did not create polarity it did not create a positive end they did not create a negative end everybody was neutral basically so therefore it was a non-polar molecule in this case because I created a positive end and a negative end you're creating polarity and that's why this is a polar covalent molecule ok so you talked about polarity polar and nonpolar only in the case of covalent molecules depending on whether the sharing is occurring equally or unequally ok ok so this table I'm not gonna go over this but this is basically an exact comparison between the the different bonds that we've been discussing for a while now which is the ionic bond the polar covalent versus the non polar covalent in examples that we just discussed a while ago are all shown here on the bottom this is just for you to kind of bring all of these concepts together as you are studying this material ok which then brings me to the very last bond we're almost done okay so the very last bond that I'm gonna discuss is a hydrogen bond yes it's a chemical bond but it's not a true chemical bond okay so you remember with an ionic bond there was transfer of electrons one of the atoms gained an electron or more electron one or two whatever and the other atom lost its electron so it was a complete transfer of electrons in the case of covalent molecules well it's still an energy partnership between electrons except it was not a transfer it was sharing a shared partnership in the case of hydrogen bonds it actually has nothing to do with electrons is there there is no movement of electrons okay remember this last slide that we talked about with water being a polar covalent molecule but you had a positive end and you had a negative end on the other okay well the positive and negative ends of adjacent molecules attract each other because opposites attract okay and and that's what forms a hydrogen bond but it's not it's not really anything associated with electron transfer or movement or sharing or any of that I'll give you an example all right this is water molecule okay so several molecules of water so here's h2o okay and here's another water molecule is several water molecules so I remember the oxygen assumes the the partial negative n so it's the Delta and negative n the two the hydrogen becomes the Delta positive n so basically these dotted lines these are hydrogen bonds okay so how did harder form a hydrogen bond it's the song it's a strong attraction or an attractive like a pull between the Delta positive end of one molecule and the Delta negative end of the adjacent molecule that forms a hydrogen bond really there was no exchange of electrons here okay so let's assume here's my Delta positive end of one water molecule it is attracted towards the Delta negative end of the surrounding the adjacent water molecule and likewise all across okay so therefore the this attraction between the positive and the negative ends of adjacent polar covalent molecules results in a hydrogen bond okay so I think that basically ends this set of slides I'm going to stop sharing here for just a second and get back to the main video that was in essence a discussion of the basic chemistry concepts starting with what's an element in what's an element made up of namely atoms and then we broke it down in subatomic particles protons neutrons electrons and then we really focused on those electrons instead of talking about what are the energy relationships that are formed by these electrons with other electrons of other atoms and that's where we started breaking it down into different types of bonds okay ionic bonds covalent bonds and hydrogen bonds as more of an attraction kind of force that in essence kind of sets the stage and gives you the fundamental concepts of chemistry that you would require to kind of move forward in our discussion and help you understand you know what are some of the chemical relationships that occurs at the cellular level within these atoms okay that's all the chemistry I'm going to be discussing in this video but keep all of these concepts in mind because in the next video I'm gonna start discussing something we're gonna build on this and start discussing biochemistry where we will focus on inorganic and specifically organic molecules and talk a little bit about the classification of organic molecules like carbohydrates and proteins and lipids and and all of that okay but so right now that this kind of concludes our discussion of chemistry and I hope it made sense to you just think about these concepts and review it over and over again if you need to and so that it kind of makes sense but you will need these concepts moving forward with the biochemistry part of it all right you