Transcript for:
Understanding Atomic Structure and Bonding

all right hello everyone um hopefully I'm not too too loud um I haven't done this in a while and I'm doing this on a new system so yeah welcome to the stream we are going to go over the exam one practice exam um which it explicitly said not to study um but we're going to go ahead and study it anyway whoops okay so here's what we're going to start with okay number one is asking the property that distinguishes an atom of one element carbon for example from an atom of another element oxygen for example is a how many bonds it forms B the number of protons C the number of neutrons or D the type of element that it could bond with Okay so let's work down the chain right so just as a start we have three types of subatomic particles right and I like to make this one red this one gray and this one yellow right so this is a proton right so proton has a positive charge and this is a neutron and neutron has no charge so it's equal right I I put it equal sign here and this is an electron which has a negative charge right so these are your subatomic particles um so all you take all of these you match them together and boom you get an atom right so for example a a a atom of hydrogen will have one proton and surrounding it is one electron and an atom of helium will have two protons because it's next in the periodic table two protons two neutrons sorry and two electrons right so as we keep on going for an atom to stay electronically neutral it has to have the same amount of protons as it does electrons right once we start changing the number of electrons then we start to get into ions and once we start changing the number of neutrons we start getting into Isotopes right so let's say for this hydrogen atom for example this hydrogen atom what if we add a neutron okay so now it's that now it's hydrogen 2 otherwise known as duum okay so what if we add a third one so now this is hydrogen 3 also known as tridium right so so Isotopes right the the okay so so so here's what each of the particles do right so electrons pretty much solely have to do with like have to do with reactivity right so especially electrons on the outermost shell and we call it the veence zone so this so so we call that the veence shell so electrons are very reactive that's what causes all the chemical reactions it's just the shifting around of electrons and the creation of bonds right so that's that's what that's what an electron does what a neutron does is it just balances out the weight and it balances out the charge with within the nucleus right so look at so look at this helium atom over here right so this is helium so what does helium do helium has two protons right but as you guys know with playing around with magnets right is that Opposites Attract and things that are similar repel each other so how is it that protons can stay together like this right how is that possible well it's through neutrons and it's through strong it's it's through something called strong nuclear force right so the neutrons help balance out the protons so that it the so that the atom can actually stay together right so that's why so that's why helium is so stable right because we only have the two protons and we have the two electrons the electrons on the outer shell are they do not want to be donated they do not want to accept anything they nothing is happening to these electrons because this is a full veilance shell right so once we get into the other veilance shells sorry well once there only one veence shell right so once we start getting to other shells then we then it goes up to like eight per shell but for the innermost shell it's two right so it's two then 8888 and then and then if you take chemistry it's like it gets weird right there's always an exception to the rule right things are not always so neat however right that that's that's the purpose of the neutron and of the electron so what does the proton do right we've been talking all this time what does the proton do well the proton determines the element itself right so let me pull up the periodic table real quick just give me one moment so my favorite periodic table um resource is just ptable.com so that's where this is from right so this is your periodic table so let's look at what we have here so we have hydrogen so we we have hydrogen and then goes all the way to helium and then lithium burum boron carbon and then just goes down the chain just down the chain right so that that's whoops sorry that's what that does right we just go down right so one two 3 four five six okay and these so so this number up here this these numbers represent how many protons there are in the atom that's the atomic number so the atomic number right the atomic number is the same as the number of protons write that down the atomic number is the same as the number of protons because you will most likely get a question like that on the exam right so that's what it is the atomic number so we have a few things here that we need to worry about the atomic number the symbol the name and the weight right so the atomic number tells us the number of protons it tells us the properties of the element right the the symbol tells us the two or the one or two letter abbreviation of the element name the name is of course the name of the element and the weight is the average of every single atom in the universe of of that of that element right the average weight right so we talked about Isotopes right so let's take carbon for example where is carbon we take carbon for example right so carbon always has six protons right but sometimes so so carbon has six protons right and it's going to have six neutrons but sometimes it has 13 sorry sometimes it has seven neutrons and sometimes it has eight neutrons right so what we do is we take the average of all carbon atoms we we like take a sample and we annihilate it and we detect what kind of or what kind of what is what it's consisting of right and when we add up the number of neutrons and protons we get the atomic mass right and the atomic mass is just the is just the mass of one atom when we talk about the atomic weight the atomic weight is the average of every single atom in the universe of that element right so carbon 12 has 12.01 rounding up right 12.01 nitrogen has 14.1 or 14.01 rounding up again Oxygen 16 right so we just take the average right because sometimes there's going to be a nitrogen with uh with eight neutrons or sometimes it's going to be an oxygen with seven neutrons that sort of thing right so I can't confirm if you guys like actually understand this so um but but yes I I would if I would if I could however that's what the atomic weight is the atomic weight is an average the atomic mass is a specific calculation of one atom right so right if we taking if we're taking like helium right if we're taking helium for example so we're just talking about helium so helium has one two protons two protons and one two neutrons so essentially what we just do is we just add this and we get we get an atomic mass of 4 AMU AMU is atomic mass unit right which I'm not sure if you need noce for the exam um we'll go into it later so M so I'm sure some of you may be asking what about electrons right so electrons are so small imagine how tiny a proton is Right an electron is 0.8% of the mass of a proton does that make does that does that make sense right um um I might okay one okay sorry yeah okay so the mass of an electron is 1.8% of the mass of a proton yeah 1.8 which is Tiny tiny tiny tiny so electrons unless there's like a lot of them they which it even then it would it would barely consider the weight would still barely be considered it's almost almost negligible but these electrons still have a little bit of little bit of mass just a little bit right but it's just a fraction of a percent a fraction of a fra however you want you say it it's so much smaller than that of a proton and of a neutron that we don't consider in in the mass calculation of an atom right so don't even worry about electrons when it comes to that however right it's so small then why do they have SIM why why is why do protons and electrons have the same charge that it is a as that is a question I cannot answer um you'll have to ask like a theoretical physicist or whatever um but yeah just I one thing I do want to emphasize is that protons and electrons have the same charge they have the the same amount of charge just one is positive and one is negative and that's going to be very important later on when we when we talk about reactivity and ions and like attractions and whatnot yeah but they have the same charge but one's positive one's negative right so anyway that was our discussion about the subatomic particles right one accounts for reactivity and that's the electrons right one accounts for stabil and that's neutrons and one accounts for the properties of the element and that's protons right so just so yeah that's the basics of the atom the atom is what makes up everything in the universe everything everything that has mass is going to be made up of atoms and of course there are other there are things that we people that scientists theorize about like um like dark matter or dark energy but anything that has mass is going to be made made of atoms right so anyway lengthy explanation over let's go back to the question right so question is asking what what distinguishes one element from another how many bonds it forms the number of protons the number of neutrons or the type of element that can bond with Okay so let's go down the line right a how many bonds it forms well okay how many bonds it forms well carbon can form wait this one okay yeah okay carbon can form four bonds right well one just one one space down one column in the same column one space down silicon can also form four four bonds right so that is not what distinguishes these from each other right just the number of bonds that could be formed I mean of course you have hydrogen hydrogen can form one and you have oxygen oxygen can form two sure those are different but that's not what accounts for for what makes them intrinsically different the amount of bonds they can form well like I said carbon and silicon they can form the same amount right oxygen and um sorry oxygen and sulfur they can form the same amount chlorine and bromine same amount again but that's not what differentiates them so how about the number of neutrons well we just went over right the number of neutrons is how you distinguish Isotopes right so that's elements of the same kind of the same amount of protons which yeah spoiler right but the number of neutrons determines the difference of isotope but not the difference of element right so yeah you could have you could have a hydrogen atom with two with two neutrons and you could have a helium atom with two neutrons that's not what makes them different right so how about D the type of element that I could bond with well all sorts of elements can can bond with all sorts of other elements hydrogen can bond to oxygen Ox oxygen can bond to carbon silicon can bond to to to carbon probably I anyway that's not what that's not all what distinguishes it so a c and d are all wrong but how about the number of protons right like I said atomic number right atomic number is the number of protons right so let's see if I have it yeah here we go atomic number is a number of protons so that's what makes each one of these different because some of these can have the same amount of electrons some of these can have the same amount of neutrons but all of them have different protons because if we change the number of protons we are intrinsically changing the element right so this is why this is why scientists or or sorry this is why why um what are they called Alchemist right this is why Alchemist would try to turn lead over here into gold right so what happen so if we take away oh and they didn't know this of course because this is really difficult to do it is possible but it's really really difficult and very expensive so what so if we if we subtract three protons bam we get gold right easy easy trick to get gold except it's really not right that's what that's what um that's what Alchemists were trying to do for so many years is that they were trying to intrinsically change the elements in which they were dealing with if we change the proton we could do exactly that right if we can change the number of electrons still the same element we change the number of neutrons still the same element we change the number of protons that's what differentiates carbon from oxygen or oxygen from hydrogen or hydrogen from Silicon or silicon from Helium all of those right so that's question number one um yeah that was a very lengthy explanation for just uh for just one question that was 16 minutes of explanation for one question so we're going to I'm going to try and speed it up a little um yeah hopefully the rest of these questions won't take as long uh try I'm trying to be comprehensive as we go along right because I'm sure a lot of you have a lot of questions right all right so next question I have a lot of trouble with this I don't know why there we go okay so question two is asking okay there's a typo all right there's a typo okay well let's just let just fix it sorry just be please bear with me and atom that's what it's supposed to read and atom okay an atom with a net positive charge must have a more protons than neutrons B pro more protons and electrons C more electrons than neutrons or D more electrons and protons okay so we can just go ahead and eliminate C right because remember neutrons don't have any charge so we could just go ahead and get that out of the equation and we do the same with a right more protons than neutrons once again neutrons have nothing to do with charge so an atom with a net positive charge so my question is right if we have a lithium atom so lithium has an atomic number of three we have a lithium atom and that has the inner shell of two right and then the veent shell so so remember again the veent shell the veent shell is the one that's going to be reacting so then so if we have at lithium we have the nucleus and we have the the inner shell which holds two and then we have the veent shell that could hold eight right Well for now right for now we have three protons and we have three electrons so three positive and three negative what happens if we add this right or let's let's uh there we go three positive plus three negative what happens if we add that zero right of course so what happens if we take away what happens if we take it away what happens if we take away an electron right if we say goodbye to that electron so now we have more protons than we do electrons right so let's count them right so we have three protons right and then we're adding two electrons which have a negative charge so we have a positive charge right that's positive so we we indicate this atom to have a positive charge so we so we would say this is lithium normally we would now say this is lithium with a positive charge kind of like looking like this right so yeah let's go back to the question if we're losing electrons we're gaining positivity right because electrons are negative and if we're gaining electrons we're getting more negative because once again you're adding negativity right so an atom with a NE positive charge must have more protons than it does electrons so the answer is B so moving on number three so we talked about Isotopes right that's what that's the name of our baseball team right or in New Mexico the Isotopes who doesn't love a good Isotopes game I haven't been to one since I was very young um if this will work please oh there we go that's what I should do okay so number three is talking about Isotopes so the Isotopes carbon 12 and carbon 14 differ in the number of neutrons the number of protons or the number of electrons or D being see so remember what we talked about how if you change the number of protons you change the element so we could just go ahead and eliminate B and by extension d right so process of elimination right so carbon 12 and carbon 14 right so what do these numbers mean what do these numbers mean right these numbers tell us the atomic mass right so when we're talking about atomic weight atomic weight is an average atomic mass is a calculation of one atom right so carbon 12 that's going to be six protons because remember the protons don't change carbon has six protons plus six neutrons or or how about this right we have 12 = 6 + x right so find find X right you balance up the equation x equal 6 and that's our number of neutrons right so when so when we add 6 plus 6 we get 12 carbon 12 six protons six neutrons and remember we do not include electrons in this calculation because electrons are tiny tiny tiny tiny tiny little things so how about carbon 14 14 = 6 + x well what does x equal now 8 so this will have eight neutrons right so that's that's just basically how you calculate the the the number number of neutrons if you don't have it um which if you you will always have a number of protons right because once again you need you need the element when the the element doesn't change the number of protons right if it's the same element and if we're trying to do this in Reverse if we're trying to do this in Reverse 6 Plus 8 = 14 carbon 14 that's thing right so that's how you calculate the atomic mass right you just take the number of protons plus the number of neutrons right so not the number of electrons right that's not how these differ so we could go ahead and eliminate that leaving a as the correct answer all right moving on okay so number four is is asking about the the most commonly found organism the most commonly found elements in organisms right so for this you have to know what these most commonly found elements are so what are they right there's four that you have to know there's four that you have to know absolutely right cuz these are going to show up for the next 4 months of this class you absolutely have to know these hydrogen carbon oxygen and nitrogen so hydrogen carbon oxygen and nitrogen so these are the four most common elements in the human body and in most living things and in all living things actually sorry I misspoke all living things have these four elements in common hydrogen carbon oxygen and nitrogen you take these four elements with a few others and you you're able to make life that's why life is so hard to find because sometimes you can't find liquid water or carbon is not available whatever right so it's just really humbling right how we are even alive honestly and how we were able to okay I'm getting too Phil philosophical let's just move on so let's let's analyze these four important and necessary elements let's analyze them right that is Tiny okay there we go so where are they we have hydrogen over here we have carbon nitrogen and oxygen all over here they're even in a row how nice right so we don't worry about boron we don't worry about theil we don't worry about lithium even though we just went over lithium right not these are not organic these are not found in organisms and not helium either as fun as helium is so what what do these have in common so let's go down the list right a is saying they all have a low atomic mass okay well I guess you can say that I mean compared to some of these other elements yeah they are very low I mean I mean look at look at r on gas it has an atomic mass of 222 that's a lot right so we can say that is that is a property of elements found in organisms right it has a low atomic mass well how about elements have an atomic number less than 21 well that's also true because where's 21 SC Scandium right well we have 1 6 seven and 8 I don't know about you guys but that's less than 21 right so how about C the elements all possess eight electrons in their outer shell the only elements that possess eight electrons in their ouer shell by default are these ones on this side these are known as Noble gases noble gases are stable they do not want to gain or lose any electrons because they're already already set right but hydrogen can form a bond hydrogen has one veence electron carbon can form four bonds it has four veence electrons nitrogen can form three bonds it has five veence electrons and oxygen can form two because it has six veence electrons right it has it still has these spots that are wait waiting to be occupied right so this one is false how about the elements are lacking one or more electrons from their outer shell we just talked about that that is true so the answer is C this one is not a property of elements this is this is not property of elements most commonly found right so so for this question you have to know what the elements are like I said you have to know these four you have to know them please please please please anyway moving on oops all right so now we're actually talking about bonds specifically now we're talking about ionic bonds so there are three types well technically two types two and a half types let's say that there are a few different ways elements can interact with each other right so we need still need to talk about bonds so now we're going to do that right so there's a few there's a couple of different ways this can happen through the sharing of an electron or through the exchange of an electron so when we share electrons okay how about that sorry one second when we share electrons sorry I have a new keyboard it's kind of throwing me off when we share electrons that is known as a CO Co valent Bond coent dong that's funny calent bond that is when we share electrons how about when we exchange electrons that is an ionic bond so yeah so there are two and furthermore there are two types of calent bonds when we share unequally and when we share equally and when we share them unequally this is known as a polar calent bond and when we share them equally these are known as non-polar coent bonds so yeah these are your three types right polar coent non-polar coent and ionic so yeah um going back to the example okay what's let's start let's have a new example right let's go to sodium right so sodium has sodium's Atomic sorry atomic symbol is na so why it's not like s so is because na is like it's like natrium and natrium like the sodium was discovered like in ancient Rome and they were speaking Latin whatever doesn't matter so sodium has an atomic symbol of Na right sodium has an atomic number of 11 right so how many veence electrons does it have right so let's take 11 - 8 minus 2 right because remember there's two because when because electrons they they come in shells right so in the inter M shell is two and beyond that it's eight right so let's let's let's Okay real quick let's explain why that's the case um because I could see why that that would be confusing right okay so hydrogen and helium have so so on the innermost shell that's two right so bam one two and then we move down 1 2 3 4 5 6 78 eight and then we move down 1 2 3 4 5 6 7 8 right so neon so he helium has two right has two veence electrons so it's it's perfectly even neon has eight right so eight so 10 - 2 = 8 right and then argon 10 and then argon 18 - 8 - 2 8 right so we just we just go we just go whoop and then we go this way and then we go this way right so elements in this column are going to have one veence electron elements in this column are going to have two and then we jump over because we we forget about the transition metals we jump over these ones have three these ones have four these ones have five six seven and then eight right so that's that's how we that's how we calculate the number of electrons right but once again the the only ones that you really need to know how many there are and how many bonds they can form are carbon nitrogen oxygen hydrogen right but in the case of ionic bonds which we're talking about now we have to we have to focus on these ones over here right and these ones over here most likely right so anyway so sodium we calculate the number of veence electrons by taking the atomic number which is 11 right subtracting it by eight and subtracting it by two right so then we get one right so one veence electron so so I would I would draw in all the protons and all the neutrons and all the electrons I'm just going to go ahead and shorthand it because that's a lot easier for me so what do I mean by shanding I'm only drawing I'm drawing the element the elemental symbol Na and then one veence electron because that's how many it has I'm ignoring everything else inside right so that's just how you shorthand it you just do the veilance shell and the name right so this is sodium sodium is very reactive I mean look up on YouTube like throwing sodium into a pond of water right it explodes it goes all over the place it catches on fire like like I said super super reactive right because sodium is dying to get rid of this this this veence electron it's dying it needs to get rid of it because it wants to be stable it wants to have 10 electrons so that has so it fills out the eight and the two it just wants to have just wants to get rid of that one that one that's why it's so reactive so what happens to this electron now well that's where chlorine comes into play right it doesn't have to be chlorine it could be iodine or it could be bromine and there other ionic bonds that could be formed right but chlorine is sodium and chlorine go together like peanut butter and jelly right these two just love to be together who doesn't love a nice little salty meal or salty bag of chips right that's where this comes from right so we have sodium and we have chlorine chlorine well chlorine has an atomic number of 17 right so that's 17 - 8 minus 2 gives us seven right so chlorine has seven veence electrons there we go seven which I had a question about this the other day um when we're when we're counting valence electrons let's use carbon as as let's use nitrogen as an example um let's do it in blue I think nitren is like a blue element if that makes sense in my mind it is we draw the veilance shell right we go one two 3 four and then we go back up top five and there was one more we would go down here again right so we fill them out individually first and then we start adding them in pairs um that was one question that I had the other day so anyway sodium and chlorine so remember how I said how reactive sodium metal is chlorine is the exact same thing right chlorine is dying to fill out that eight shell that that shell of eight it's just dying to get 18 electrons well these two can solve each other's problems right sodium can go ahead and just donate its one electron to chlorine and chlorine can accept that one electron making a full shell for both of them so in this process of losing this electron and giving it to chlorine this process of losing and gaining right so let's uh let's let's just cross it out because yeah whatever so in this process of loss and gain sodium now has a positive charge because we Lo we fully lost an electron and chlorine has a negative charge because it gained negativity so do you remember what I said about opos subtracting bam that's what happens opposite that's attract and what happens to these is that we if we have a lot of sodium sodium ions cuz remember these are now ions because we we we have a different number of electrons than we do than we started with that's an ion that's what an ion is when we have a different number of electrons then we do protons when we have ions they kind of create a sort of lattice when we have a bunch of them so let me let me show you just give me one moment right so if you ever if you ever look at like salt underneath a microscope right you will see that it has like this sort of crystalline structure it's it's creating it's like cubic right it's it's it's very very it it orients itself in cub in like a cubic formation that's what's going on here that's if you look at a molecular level or at a atomic level rather if we look at an atomic level we can see how these ions are orienting thems in space right so we have these purple sodium ions and these light blue chlorides right so these are just they're just like attracting to they're just attracted to each other and and through this they create a bond and this is an ionic bond an ionic bond when they because they're both ions right so the the electrostatic interaction between them keeps them together and that it's that and that is its own compound now so chlorine no longer has the properties of regular chlorine it has the properties of a chlorine ion and same thing with sodium sodium is no longer a a highly reactive metal sodium now tastes good right it it tastes delicious right that's why we love salt salt is salt is awesome right so that's what's happening here if you if you if you licked sodium metal it would not end well but if you lick like a rock of salt tastes delicious right and this is why because the properties of the element changed because we changed the number of electrons right so that's an ionic bond so once again super long explanation for one question so ionic bonds arise from not shared not Shar veence electrons because remember remember this this sort of flowchart that we have going on here it's through an exchange right so not shared attracting between neutrons well once again neutrons cannot attract anything because neutrons are neutral right attractions between ions of opposite charge okay we're getting somewhere and attraction between neutrons and protons once again drop the ball not neutrons can't be neutrons neutrons do not attract anything so attraction between ions of opposite charge that is what an ionic bond is Ion of opposite charge they like to hang out together now right that's what it is it's as simple as that right yeah so moving on um well let's Okay so while while we're on the topic right while while we're on the topic let's go over let's go over coent bonds right so let's just go ahead and delete this this question right because we're no longer talking about it let's let's take let's take this this little thing right so we were just talking about the full exchange of electrons and that's an ionic bond so what about a calent bond what is a calent bond what does it mean to share electrons right well let's find out let's take hydrogen hydrogen is the most simple example is Right hydrogen has just one valence electron just just the one right so if we take another hydrogen atom it has also just the one right yes okay so these two want something to happen that electron so hydrogen has a couple of different options either it it can donate its electron that is possible we will go into that later in the semester or it could share it most times it'll share it in certain cases it won't but hydrogen just just hydrogen is very versatile so in this case when we're bonding hydrogens together right when we're bonding these hydrogens together what is going to happen between them right because they both need two but if but we don't but it's not exactly favorable for one to donate and one to accept so what happens now what happens is they share bam they share that's exactly how it happens right so let's let's let's let's start like this right so we have one hydrogen atom with one electron here right and then we have another hydrogen atom with one on the other side so what's gon to so what's going to happen now they are going to be shared just like this bam oh that's kind of misleading um Let me let me think about this for a second okay okay nope this this is wrong okay I know now I I got it I got it sorry you guys are going have to bear with me so these two they come together and there we go they come together and now uh sorry this that's still like kind of okay let's let's get them as close as we can right bam okay touchdown right so we've got we've gotten them as close as we can right so when they get close together like this now they could actually share electrons right so this so this this one can like essentially just make a bridge and this other one that we kind of erased can also make a bridge and that's a calent bond they're sharing right isn't that beautiful don't we just love sharing right some some of you may maybe not I hope I hope that's none of you but some of you maybe hydrogen hydrogen items love to share carbon atoms love to share all these elements love to share electrons right hydrogen specifically can only share one so hydrogen is sharing one with another hydrogen and that same hydrogen and that other hydrogen is sharing one with the other one so they have now completed each other's shells which is great because now they're both happy so now we call this we call this hydrogen two with a little subscript two right hydrogen gas that's what this is hydrogen gas so when when we when you light hydrogen gas in fire because this is highly flammable when you light hydrogen gas on fire we just get water okay so so when we add oxygen to the mix um yeah we just get water and some heat right um that's a chemical reaction um you need to worry about that for now um I in fact I don't even know why I'm going over it if I'm being honest okay so that's just a coent bomb is when two atoms like to share their electrons so they they fulfill each other's needs right complet making an entirely new compound or yeah making an entirely new compound or element right just just through the sharing of electrons right so as kids right sometimes you would get into arguments with your friends or your siblings about sharing things right so let's talk about water now right so hydrogen and hydrogen they have about they have the same strength because they're the same element right they share these electrons equally so remember going back to the flowchart when we share equally that is a non-polar calent Bond so there is there they're sharing them equally there are no poles and we'll go into what that means later there all there are no poles there is no positive or negative charge these this is neutral it's non-polar there is no there is no um there is no like charge associated with this with this compound right but like I said let's move on to water so water right is H2O so what does that mean you've heard that your entire life probably water is H2O it's probably the only chemistry related thing that you knew for years and years of your life but what does it even mean right so oxygen has a veent shell has a veence has it has six veence electrons right so remember we count one 2 3 4 right and then five six so yeah so we have two unoccupied spaces in which we could bond two electrons that are willing to share because these are known as lone pairs these are LP loone pairs these are loan pair because they don't they don't there is no there's nothing you could do with them right they're happy as they are they exist in their own little space right because we we want these electrons to be paired right that's ultimately the goal we want these electrons to be paired right so of course in hydrogen in the example of hydrogen they already are they're you're you're already looking for one pair right when we when we get to the the outer shells like eight and eight and eight right when we get to the outer shells then we start to discuss the Le alone pairs so we want these electrons to be in pairs right so there's one pair that can be made here and one pair that could be made here so let's take let's take hydrogen again right so hydrogen has just the one just the one electron and hydrogen has already gone ahead and bonded to to oxygen okay and we do that again with another with another hydrogen because once again there are two opportunities for sharing here right just like it did with just like just like hydrogen did with itself we do here with oxygen right so bam just like that so now we have a water molecule this is a water molecule H2O good old water couldn't live without it literally so so so now everyone's happy here hydrogen filled out its one veence electron it filled out that pair both of these did right and oxygen has a full shell of eight now because now we're sharing right however oxygen is a little bit greedy so this is where we get into the discussion of electr negativity electr negativity right so electro negativity every single element has its own electro negativity value hydrogen has like an intermediate amount oxygen has a very high amount so what the heck does the electr negativity even mean electro negativity means the affinity for an element to pull electrons towards itself did you get that electro negativity means an element's Affinity to pull electrons towards itself what a mouthful right electr negativity in itself is also a mouthful right but what is essentially saying here is that oxygen is that oxygen like I said has a high electro negativity hydrogen has like medium right so essentially what's going to happen is that these electrons are actually going to be pulled closer to oxygen than they are to hydrogen right so if you had a kid if you knew someone that was a little bit greedy with their toys right they like to hold on to them a little closer but you're just still trying to share so you grab out your arms right that's what oxygen is doing right here hydrogen is here hydrogen bonded a hydrogen H2 they're happy they're happy together they they they share they share equally here with water they share unequally right oxygen is a bit of an electron hog right because if it's high electro negativity so here I've drawn what's known as a dipole dipole essentially just shows is essentially a vector of where the electrons charge is going right it's it's it's a vector of where the electron's charge is going so the charge is going towards oxygen as we see here so again if we add vectors together so essentially bam it's just kind of like that right so that's what's going on here right so in this process in in oxygen Hawking all of its electrons together right we then create a partial okay so so this is this is a lowercase Delta this is partial this means partial right we we create a partial positive charge here in one hydrogen a partial positive charge here in the other one a partial negative charge on the opposite side and then another one here bam that's water water is the only molecule as small as it is it is the only molecule that can have four different spots that are partially charged like this and this is what we when when we say something is polar this is what we mean so you think of the North Pole you think of the South Pole you think of the magnetic poles right you have a magnet let's say you have a magnet so who who loved playing with magnets as a kid I love I love magnets so we have one side we have one end that's go heading north and and we have the other side that's heading south right North and South in the same sense so that's that's those those are magnetic poles in the same sense we could say that about this molecule right with the polar coent bonds we could say that about this molecule one pole is positive and one is negative it's a simple as that really it's just like a magnet one one side is positive the other one is negative right so if we take this right and we like root I don't know how to rotate this I'm be honest with you guys and so this this side oh it's going to be attracted to the partial negative and this side oh it's going to be part the partial positive right because remember Opposites Attract guys this is this is it's all you guys have to tap into your logic you have to tap into things that you learned as kids you have to tap into like everything that you know because this is what we're made of this is what we're made of and we're learning about what we're made of isn't that such a beautiful thing that we're learning this we're able to understand this guys I'm telling you I'm telling you this is so important the fact that water is able to do this is magical it is almost I mean I we have the logic right here we could we could study it we could we could look at it but guys I'm telling you this is magical the fact that water is partially positive in one side and partially negative in the other and that has an entire slew of different things that it could do with that right which is why we're going to go into hydrogen bonding next right so let's delete this magnet we love magnets right like I said um sorry one sec okay so let's uh let's go ahead and uh erase some of this you have to bear with me I'm I'm this uh this software that I'm using some of you may recognize it uh it's not the greatest in the world um it is free and I am used to it however so you know you work with what you got right and let's go ahead and fill in these dioles too why not or let's just go ahead and erase them okay that didn't do what I wanted you guys are just watching me struggle at this point you have to bear with me okay so we just talked about polar coent bonds right how one side is partially positive and the other side is partially negative right and that has to do with the pull the the electron affinity for oxygen oxygen pulling itself pulling sorry pulling the electrons towards itself from hydrogen right making itself more negative and making the hydrogen's more positive so what do we do with that well what happens if we go ahead and add bam another oxygen sorry sorry sorry another water molecule do you remember what I said about opposite attracting well once again that is coming into play right because what's happening here let's add in let's add in some partial charges so we can see what's going on hydrogen has a partial positive charge right and this lone pair or this this side of this side of water has a partial negative charge so what's going to happen here hydrogen bonding that's what it's called hydrogen bonding so what we discussed over here this is what's known as inter sorry int molecular forces intra molecular forces hydrogen bonding is an example of inter molecular forces intra meaning within inter meaning between right so ionic bonds and calent bonds those are intra molecular forces so when we're talking about inter so so intra that has to do with the bonds within the molecule right so these polar equivalent bonds that's within the molecule right so good inter is between other molecules so we have one one water molecule here and one here right these couldn't form a hydrogen bond without each other right they need each other to form a hydrogen bond which is why it's between two molecules right but so but back to the back to the topic right right here we have a partial positive charge and a partial negative charge what is going to happen with these right what's going to happen with these is that they're going to attract to each other which like I said magical water is incredible for the its ability to do this and they could do it with four other spots on the hydrogen molecule like literally if we take multiple of these they just they just create this lattice they create this beautiful structure of just water interacting with each other like like an entire like ecosystem essentially of just water right through the through through sheer electrostatic interactions like hydrogen bonding these are attracting to each other one is positive one is negative bam they come together just like that however however it's not like an ionic bond where they stay together they stay together really well like in that lad structure we saw earlier it's not like that where they sa together really well these bonds are incredibly weak right I mean if you have a bottle of water next to you just shake it just shake it around right and you'll and you just by doing that you broke apart millions and even probably billions of hydrogen bonds just by shaking around your water bottle right cuz these are constantly moving they're constantly shifting around it just takes a little bit it just takes a little bit of force to get these to get these apart right and we'll get why and we'll get into later as to why that's super duper important in biological systems right because if we were if if everything was coent cently bonded in our bodies right uh really bad things would happen because well for one you you wouldn't be able to breathe right what what if your cells were just locked in one position for its entire lifetime right hydrogen bonds are incredibly important are incredibly important that's why that's why water has surface tension right that's why that's why that's why certain bugs can walk on water they take advantage of this these properties of water that you're able to do because of hydrogen bonding hydrogen bonding creates like a sort of like a sort of like here's another example right in movies in action movies specifically you often have like a guy jumping out of a helicopter or falling into water from a certain height water acts like concrete right I don't know if you guys have ever went into the swimming pool and belly flopped onto the onto into the pool right it's painful that that quick like slap of your body and the water is because of hydrogen bonds right these hydrogen bonds like to stay together they keep water together that's why water is that's why water takes forever to boil right it's because we're breaking apart these hydrogen bonds it's incredible thing hydrogen bonds are super duper important right and it only happens between polar it can only happen between molecules that are polar right so this so water is a polar molecule right because it has polar coent bonds because oxygen is sharing those electrons unequally right so with that in mind right with the properties of water in mind and with polar calent bonds in mind and with non-polar Convent Bonds in mind right just take that all into consideration so we have so this is a property that's that's present in water the ability to hydrogen bond that's not present here because remember this molecules that share equally are nonpolar they are non-polar molecules that share equally are non-polar molecules that share unequally are polar right and like I said that all has to do with electro negativity so one big takeaway one thing that you're probably most interested in in in learning one thing that you have to remember is what bonds are polar and what bonds are non-polar calent right so I'll tell you carbon bonded okay well for one anything bonded to itself non-polar right the electro negativities just cancel each other out they share equally perfect right so that's oxygen bond to oxygen non-polar hydrogen bonded to hydrogen nonpolar carbon B to carbon nonpolar anything bond to itself non-polar that's what I'm trying to say here so oxygen gas O2 that's what we breathe in right that's that's in the air this is a double bond I'm going to draw which we don't need to know about double bonds quite yet that's basically what it is non-polar right despite the fact that oxygen is such an electron hog it's still nonp because it's still bonded to itself just like hydrogen over here right so anything bond to itself is going to be non-polar let's write that down anything Bond into itself is nonpolar good good so now we know that so how about everything else right well there's only a few bonds that you need to know their properties right and they are carbon bonded to hydrogen is nonpolar carbon Bond into oxygen is polar carbon bonded into nitrogen is polar oxygen Bond into hydrogen as we learned is polar yeah I think I'm missing one um oh yeah and nitrogen bonded to hydrogen is polar so all of these you have to know right you have to know for the future not maybe not necessarily for this exam even though it will be certainly helpful especially in the case of hydrogen and oxygen in fact no no no no hydrogen and oxygen and carbon and hydrogen are the ones that you definitely need to know for this exam but in the future these are all the ones that you need to know most of them are polar right because nitrogen likes to nitrogen is a bit of an electro nitrogen is a bit of an electric sorry nitrogen is a bit of an electron hog Just Like Oxygen right but what about carbon hydrogen right these share almost equally they have carbon has like a medium electro negativity hydrogen has a medium electro negativity as well right so good good yeah um so we learned all about bonds right how wonderful is that right we learned all about bonds this is the this is the foundation for what we're going to learn throughout the rest of the semester right so let's look at this right so let's let's look let's look at this uh this periodic table so we're going to we're going to ignore hydrogen for now elements on this side on the left hand side elements on this side are going to want to form ionic bonds because they're just dying to get rid of those electrons right elements in this column spefically have two electrons that they want to get rid of elements in this column want have one so if you ever see anything about sodium potassium lithium they have one and for two if you ever see anything about strontium probably not um calcium and magnesium is going to have two which the question will let you know if how many electrons it has or its atomic number which you could assume the the the veence electrons that sort of thing and elements on this side are going to want to Cove valent Bond these are going to want the coent bond right with a few exceptions right we learned about sodium chloride right so these are going to want to just fill up that one last electron right that one last electron in its shell that's what Florine chlorine and bromine want to do and iodine um but they're a little bit different right solely because they are still able to form coent bonds with each other for example Florine whoops for example Florine can form a coent bond with itself and chlorine and bromine and iodine all these can form bonds with themselves right which we which these are all what are known as halogens right I love halogens halogens are so cool anyway um just as a general tendency these want to these want a calent bond with the exception being these ones which they can ionic bond but they can also coent Bond except for and but but in the case of these These are almost always going to be ionic bonding right so you ever see sodium and chlorine or magnesium and chlorine or lith or potassium and Broman you're going to it's most likely going to be an ionic bond everything else most likely going to be coent Bond and remember remember right we we learned we learned about the the the the five bonds that we need to know their properties of the Polar calent versus the non-polar calent these are these ones right these ones so yeah yeah anyway we're about an hour and 10 minutes in and uh uh we're not very far through the actual exam which is hilarious right um so we're going to so we've learned pretty much everything that we need to know for the rest of the exam we've learned almost everything and if there's something that hasn't come up we're going to talk about it so with that being said we are going to speedrun through the rest of the practice exam let's do it yeah so um let me find the next question six right it's been an hour we've answered five questions can you believe that it's just it's it's all it's it's all my fault right I I I spend a lot of time explaining things which I hope is helpful for you guys yeah anyway number six a molecule with polar coent bonds we just learned about this right we just learned about this a molecule with polar cavent bonds will be soluble in water not soluble in water contain atom with very similar Electro negativities or B and C are correct okay so anything with polar coent bonds what is the polar coent bond again right so one thing I I should one thing I should say is that water is not the only molecule that is able to make hydrogen bonds anything with an o or an NH or an OC or a CO whatever all of those have the potential to make hydrogen bonds right that's why sugar is dissolvable in water that's why you could dissolve sugar in water because sugar has tons of O's right but it's but sugar isn't water right but it can still dissolve in water it's still soluble in water meaning being able to be mixed in water well how about oil oil is almost entirely made of ch's and CHS are non-polar right so another another big principle that we need to know another big principle is that like like dissolves like like dissolves like that is a huge huge principle right so if you have something that's oily it's going to want to dissolve in something in something else that's oily oil and water do not mix cuz they're not alike each other something that's dissolved something that's able to be dissolved in water is going to water mix with water like dissolves like but it's not going to want to be able to dissolve in oil right have you ever tried mixing sugar and oil I mean I'm not really sure what would happen but I don't think it would mix nearly as well as it does with water right because they're not similar to each other so a molecule with a polar coill bond meaning that is it is able to make hydrogen bonds it's able to mix with water because they're both polar they're both able ble to have that interaction with each other right CU one's positive one's negative right they're both able to make that interaction that would be soluble in water so that's the answer a would be soluble in water so B and C are not correct right because what is b not soluble and what is C adds with very similar electr negativities so what did we just say about oxygen being an electron hug right oxygen has a very high electro negativity oxygen loves to pull the electrons from hydrogen so a molecule with polar BNS would in fact not have very similar negativities in fact they would be quite different moving on um so we were just talking about this right we're just just talking about this hydrogen bonds are formed between any molecules that contain hyd hen which not true we just talked about hydrogen gas which is non-polar right because it's hydrogen bond to itself so any molecule that contains hydrogen will not necessarily form a hydrogen bond B only between water molecules once again not true because what sugar can form hydrogen bonds right that's that's why sugar is able to be dissolved in water right it has that it has the ability it has that polar um that polar quality about it right see when hydrogen is part of a polar bond okay now we're getting somewhere and then when two atoms of hydrogen share an electron not true once again we just talked about we just talked about hydrogen gas so when hydrogen is part of a polar bond what is that right that's o and H and that's n and H right so hydrogen with that partial positive charge is able to seek out other negative charges around itself right so that partial charg is able to seek out the negative charges and the negative charges on oxygen are able to seek out positive charges bam C is the answer so oh sorry if I keep blinding You by turning the screen way all of a sudden um okay so uh once again we just talked about this guys there's not a whole lot that you need to know for this exam and I know it seem very daunting essentially joining chemistry class right because this first this for this first like quarter of the class is mostly chemistry but guys there's not a whole lot like that that that you need to like remember you just have to understand how they how each of these Concepts relate to each other and how to reconcile with that right because we've talked about nearly everything and everything is just kind of coming up now right so what eight is asking if you shake a bottle of oil and water and let it sit it'll separate into two phases because one is polar and and one is non-polar so what does that what does that tell us a the non-polar oil oh wait sorry I should have read that bam D the non-polar oil is not soluble in water because remember water is a polar solvent oil is not like dissolves like and these are not alike each other so D would be the answer right and water cannot form hydrogen bonds with oil um because oil is primarily cnh right so so yeah if you answered B if you answered b um just think sorry sorry I gota I gota like I got to cool down a little bit so if you answered B um just think about it right um if you shake bottle of water and if you mix oil and water it says in the question it will separate right so water can form hydrogen bonds with itself right but water doesn't separate from itself that would be silly right so if water can form hydrogen bonds with oil wouldn't it make sense if it actually could it actually couldn't separate even if you didn't no necessarily anyway if the answered C right po polar oil is not soluble in water well like I said like dissolves like right so polar so water is polar if oil were polar then it wouldn't have separated in two faces this is this is like this is like B with extra steps right or C or or B is C with exra STS anyway oil if oil were polar it would not have separated right it would be soluble in water so yeah anyway let's move on okay so number nine is asking whoops oops sorry give me one second number nine is asking the mass number of an El the mass number of an atom is 15 and its atomic number is seven the atom probably has seven electrons in the nucleus at least 15 electrons about as much mass in electrons as in protons seven units of negative charge in the nucleus eight neutrons in the nucleus so let's look at this right seven electrons in the nucleus are electrons present in the nucleus no a is at right um seven units of negative charge in nucleus well okay well what has negative charge electrons what has positive charge protons what is in the nucleus protons D is out about as ma about as much mass in electrons as in protons well do you remember what we said earlier about an electron containing 1% of the mass of a proton again that one's out so so the what's left is at least 15 electrons and eight neutrons so what is it so atomic number remember that represents the number of protons that's what atomic number is now the mass number tells us how heavy how heavy the atom is right how many neutrons it has how many protons plus neutrons that it has so from this we can calculate 15 - 7 gives us eight right so what does it leave us with e is the correct answer um but what about B right what about B at least 15 electrons so there wouldn't be at least 15 electrons there would be at least seven right because the atomic number is seven that is the amount of protons and for that for that to be equal for them to be equal for it to be stable for it to have the same amount of positive as it does negative it would need seven electrons not 15 because 15 is the number of mass so this would so this would be the pro so at least 15 electrons would be the amount of protons plus neutrons which is not the case so yeah moving on okay number 10 two atoms always represent the same element if they have the same number of shells electrons particles in the nucleus same mass number or same protons okay so do you remember what we said earlier all the way back like an hour ago at this point how the different particles have their own different thing going on electrons changes the it has to do with the reactivity of the atom neutrons stability protons it changes the atom itself it's the it's the property of the atom right so mass number can change change the number of neutrons right number of particles in the nucleus can change that's also neutrons number of electrons can change that's ions number of shells electron shells can change because if you get rid of one or if you add another one all those can change they get still be the same element however what never changes is the number of protons because otherwise you change the element so that would be D moving on we have number 11 so number 11 is saying oh dang it okay number 11 is saying calent bonds hold atoms together because they a allow atoms to fill the veent shell so we could just ignore that one right we don't allow atoms to fill a veence shell we allow electrons to fill a veence shell right um B bring electrons closer to protons not true right electrons like to stay in their shells right they don't like to go to the nucleus C rely on electrostatic attraction okay that's that more Des that more so describes ionic bonds that describes ionic bonds right so we can go ahead and eliminate C or D atoms are always more stable when they share electrons bam that's our answer just just the fact by just the fact by share share electrons that's coent bonding right which is also true you know they are more stable than they would be with the other things that they describe I mean calent bonds are of course the most stable bond that there is um number okay so let's move on to number 12 and oh dang we're not even halfway done oh my goodness please bear with me um this can this is a little bit lengthy yes so we're just going to go ahead and go through the rest of it because that's what I'm here for right we are now we're in 25 minutes in yes sir we we are like I said we're I I said I would go through these quicker but some of these still require the explanation that they need right so number 12 when an atom of oxygen sorry I had to crack my bag when an atom of oxygen makes a calent bond why does the atom's charges take close to zero um okay so this is this is a question that's not going to be expected of you um basically what this question is saying right so I'm just going to tell the answer it's B right the answer is B um but why the atoms charges when when an atom of oxygen does make coent bonds the veent shell no longer has six electrons we can eliminate that the electrons loose the atom loses electrons from the shell also not true and the charge isn't zero it's -2 um not true all right so why why is B the correct answer shared electrons always aren't always near oxygen well do you remember how I said that oxygen is Mo of an electron hog well that's only for most of the time right because sometimes sometimes maybe an electron will be closer to hydrogen right or maybe it'll be further away from oxygen maybe it it could it could be basically anywhere because electrons are very finicky they are very fast they're very quick they kind of do what they want that's an electron right so shared electrons aren't always near oxygen because sometimes that shared electron is going to be near hydrogen right and sometimes that Shar electron is going to be near the other hydrogen right or maybe it's going to be near carbon or whatever right so the atom's charge stays close to zero because well yeah but this question like I said is most likely not going to be expected of you CU that's that's that's a very like chemistry question that was from like 21 that's that was from like 20 2110 which is a few years ago at this point um so number 13 so which answer helps to explain why carbon atoms tend to make four coent bonds well okay well the first electron sh needs four electrons that's not really true um because it's not the first it's not the first shell it's the veence shell which is the second shell right the carbon nucleus has four protons which is not true it has six right um the veence shell only the ve shell initially only has four electrons this is true so we could we could say that's correct the carbon will form an I losing four electrons super duper unlikely in if not impossible no and none of the above carbon makes three coent bonds not true it can make four so the answer is C right so carbon can make four calent bonds simple as that right veent shell uh initially only has four electrons uh so that means it has four spots that are able to be that are able to be filled right so we have carbon right we have the so this is the veence shell we have one two three four unpaired electrons we could share share four bonds just like that right okay moving on dang I did it again okay okay an N an ion with a charge of -2 has eight protons the ion also has what okay so eight protons eight protons so when this wasn't an an ion an ion is just a an ion excuse me sorry an an ion is just an ion with a negative charge and a cat ion is a is an ion with a positive charge right so that's a negative charge right so initially eight protons this at one point had eight electrons so with the charge of negative2 that means we added two electrons so when we add these together we get 10 right so that's our answer 10 electrons so anion I think is is a word that you need to understand for the exam and Cat ion is also another word that you need to understand um it's just like I said it's just an there are just two types of ions one is positive one's negative cat ion is positive and ion is negative so yeah U moving on and speaking of cat ions my cat has decided to make a guest appearance so if you hear a meowing or causing General Mayhem he is here with me so number 15 has an image attached to it so I'm going to try and put that here now there we go so number 15 is asking the atoms shown here will become ions if they meet because a a nearly full shell has little attraction for electrons okay B atoms tend to have tend to have filled veence shells or will and will take or donate electrons to fill the outer shell okay that one's true right or C A Nearly empty shell attracts electrons very strongly okay so if you if you switched up a and C if you switched up their definitions they would actually be correct and therefore D would be correct but they're not so a nearly empty shell attracts electrons very strongly not true it is very much I'm thinking about it these definitions don't even really make much sense um attracts electrons very strongly a nearly empty shell attracts electron no what would happen is an empty shell would want to get rid of the electron as much as they possibly can if anything in near the empty shell would have little attraction so what about nearly full nearly full would have a very high affinity for electrons because it wants to fill that shell right so B would be the incorrect answer sorry D would be the in incorrect answer leaving b as our only option um atoms tend to have filled veence shells and will take or donate electrons fill shells so let's just see what's going on here um we have one so we just like just see what what would happen to these two right these will probably become ions because this one just wants to donate it one and this one wants it wants to accept the one right so bam it's going to give it it's going to give that electron there and it's going to get rid of this one so that's why they would form ions and like I said um I atoms tend to have filled Adams tend to have filled villain shell when they want to take or donate electrons to fill it right like that's that's how they would F anyway sorry oh my gosh this is this is this is exhausting I think I need a glass of water or something anyway um yeah I'm going to try and I'm going hopefully try to keep this under two hours because I know it's like it's late at this point at this point in time of posting it it is quite late and I apologize for that I've been quite busy the past few the past few days and I really want to get this video out sooner but I had a lot of te technical difficulties as well um anyway so number 16 has another image associated with it oops so each carbon atom in this molecule is forming four coent bonds okay so this right here is a double bond which is essentially two calent bonds right just back to back right it's where they it's where we take two unpaired electrons and we just pair both of them to the same element right so in this case hydrogen sorry in this case oxygen has two unpaired electrons that's that are both bonding to carbon however so they so they count for two Right double bond makes sense right so let's let's so this this question is asking to focus on the carbons right so this one this carbon atom has four okay this one has four okay this one has five right so we have one two three four five so that makes this false okay so once again we just talked about this we just now talked about this no need don't even stress we just discussed this one right within a water molecule within a water molecule the atoms are held together by blank bonds and two water molecules are held together held together by each other by blank bonds right so remember inter versus intra molecular forces between versus within right so within a water molecule these atoms are held together by what polar calent or non-polar calent well o and H H2O o and H is one of one of the few bonds that I told you to remember right and what are they polar coent right so we can just go ahead and eliminate a d B and B right and C for that matter um and two water together to each other via hydrogen bonding because remember H bonding is inter molecular force it happens between two molecules okay moving on to 18 okay Florine or Florine Florine has an atomic number of nine how many electrons are needed to complete the veilance shell of a Florine atom well 9us 2 equal 7 so we need one more um so that's going to be a nine uh we don't need nine electrons because it already has nine electrons right um seven I don't know where seven came from it has seven veence electrons sure um other than that it needs it needs one more to fill it out zero well Florine is not a noble gas it's still it's still has the one electron that it needs to pair um yeah and three I don't even know where three came from this is just the most wrong one it needs one electron because remember if it's under 10 if it's under 10 um it's the number minus two it's over 10 it's the number minus 8 sorry if it's under 18 it's the number minus 8 minus 2 if it's yeah we won't we won't get anything over 20 right so in this case nine right so that's 9 minus 2 seven right because we have the inner shell so atomic number of nine nine protons nine electrons minus 9 minus 2 seven seven veence electrons we need one more fill shell right something like sodium sodium has 11 right 11 minus 8 - 2 = 1 it needs to get rid of one to get to fill the veillance shell oh this one's a long one all right a calent chemical bond is one in which electrons are removed from the atom and transferred to another so they become oppositely charged well that sounds a lot like ionic to me so we just go ahead and cross that one out B protons and neutrons are shared by two atoms to satisfy the requirements of both atoms so key word is neutrons here they don't share neutrons neutrons stay un unopposed outer shell electrons of two atoms are shared to fill the electron shells of both atoms that one's most correct so far electron outer shells of one atom are transferred to fill uh trans okay transferred right so that sounds like exchange right again ionic bonding not the case um and E an electron occupies a hybrid orbital located between the nuclei of two atoms what the heck does it even mean I mean honestly what the heck does it even mean I mean did we learn that at any point no we did not that one's wrong and so the answer is C they are shared they share electrons between two atoms we learned that correct yes we did all right next question okay so number 20 is saying what is the maximum number of calent bonds with an element or sorry what is the maximum number of calent bonds an element with the atomic number of eight came with hydrogen so if you know what the atomic number if you know what the element with atomic number of eight is this super easy but let's assume that we don't right so remember 10 if it's under 10 right you just subtract two right so what's 10 minus two right that's where did I get 10 from sorry what's 8 minus 2 that's six right so six veence electrons so that means so if we take 8 minus 6 then that means there are two bonds that are able to be formed two bonds are a be performed right so how many how many calent bonds what's max number of coent bonds in element with Toom number of eight can with hydrogen the answer is two so that's our answer two okay so this one this next one is going to require a little bit of explanation where's C we're missing one oh well actually there is no C sorry oh dang it okay there we go okay so this question is asking when salt is dissolved in water which Bond described below is not broken well the answer is this one uh that one's not broken these other two are broken um but that's not satisfying enough so what's going on here so what is what is salt what is table salt na a CL and we discussed that earlier right how these are both ions right and they like to stick together VI an ionic bond um but what is water well water is H2O right and what does water have polar calent bonds what are polar calent bonds able to do hydrogen bond right so these have partial positive charge the the hydrogen's do and then the oxygens have partial negative right so what's essentially going to happen is that the water is going to pull apart the salt right I mean I'm sure you guys know how easy it is to dissolve salt in water right it just like happens like that right very simple right and that's because of this that's because of these partial charges right these this positive charge on the hydrogen is literally pulling it's it's pulling itself towards the negative charge in the chlorine right and similarly the positive charge in the in the sodium is pulling itself towards a negative charge in oxygen right so then these get pulled apart right they're so now we have sodium ions in solution and we have chloride ions in solution right which you don't need to know necessarily what that means but just know that this process an ionic bond is broken and a hydrogen bond is also broken because we had to break apart hydrogen bonds to do this right we had we had to do it um because hydrogen bonds are constantly being broken anyway um but we but in order to do this sodium is attracted attracting those Waters to itself and chlorine is attracting again the waters to itself so it's in that sense it has to break those those hydrogen bonds right so water is literally like it's literally breaking apart salt right in this process um and what water can do is it can literally like surround itself right so it could it's just like uh shoot sorry there we go and if I could rotate this I would um this uh I could probably try and uh let's see uh yeah there we go okay um yeah that's close enough so yeah that's this is for sodium right all the the negative oxygens are attracting it attracted to the the sodium right and over here um it would be for the hydrogens right just like just like that right it it love these Waters just love to be near those salt because just just because of how attractive they are to them right so that's number 21 so let's let's see how we're doing on time um about an hour and 46 in we're probably going to get done with this before 2hour Mark which again I know it's late I I really apologize uh I could talk fast sometimes but if you really need to you could watch this video and excuse me two times speed anyway um so number 22 is asking which term refers to substances that are not easily dissolved in water okay um if you guys looked at my if you guys looked at my um terms my Greek and Latin prefixes and sub suffixes you would know what philic phobic and hydro mean right so what are these so if you didn't look at it I encourage that you do but in case you didn't Hydro means water phobic means fear of and filic means affinity for or liking of so what term refers to substances that are not easily dissolved in water um well all of these are are easily dissolved in water right something that's hydrophilic remember like dissolves like for ionized um well ion are charged right when we saw we saw just how much water likes I ions right they like to they like the they like the charges right polar water is already polar remember like disol his like so the term here would be hydrophobic so something like fat would be hydrophobic something like oil would be hydrophobic something like a steroid would be hydrophobic and that's going to come in that's going to be super super helpful later on so number 23 which of the type of calent bond represents a non-polar calent Bond do you remember what we talked about earlier what did I say what what were the five that you need to know o and H C and H CN o CNN nnh H well which one here is the only non-polar cavent bun that we talked about it's going to be b o and H super coent CN sorry o o and H super polar CN again polar um see yeah moving on the next one is like a matching um so we're going to we're going to we're going take a take a little screenshot so which type of coent oh wait sorry uh it's gonna mess up oh never mind okay what were we saying okay so match the terms with the correct definitions number 24 describes a substance that cannot be broken down into any simpler substance that sounds to me like a neutron just kidding it's it's it's an element it's an element that is an element so we got that one down um number 25 the weakest type of interaction found between molecules in cells that would be a Vander wall force which before we go I will discuss Vander Wall's forces so number 26 the subatomic particle that does not contribute to Atomic atom's weight well neutrons definitely do and ionic bond does not apply here so the answer is e electron so what in the heck are Vander wall Vander wall forces matter wall forces are interactions between molecules that are so weak that they barely even count but are ultimately very important I like the example of methane right methane and octane so methane so okay for for starter okay there we go um something there was like a disconnect that happened for a second there sorry about that where was I um so yeah consider how consider how weak hydrogen bonds already are technically and like make like a fraction of percent of that Vander wall forces are very very weak so what if what essentially a Vander wall force is is is that it just describes like that that in a in a fraction of a fraction of a second literal like Nan or even some cases ftoc like such a short inconceivable amount of time there is a there would be like a slight a negative charge here excuse me sorry there would be a slight negative charge here in the hydrogen and a slight positive charge here in the carbon and then it goes away fraction of fraction of a second right super super short so this very very slight electrostatic interaction attracts these carbon attracts these methane molecules for like a split second and they split apart right for a split second and then they go away right because methane is a gas right methane is what cows burp out it's natural gas you could burn it that sort of thing that's what methane is right now there's the other example of octane so octane um so octane has eight carbons in its chain and with each carbon is a hydrogen um oh man this going to take forever sorry so essentially octane okay so what is octane for one octane is the stuff they put in race cars to make it go faster right it's it's fuel essentially it's really efficient fuel so octane is literally like eight times the size of methane is right so if we take another octane molecule if we take another one of these and they interact with each other sorry my cat just like dis appeared out of nowhere um if these if these molecules interact with each other it's going to be a much larger interaction than than methane was so that's why octane is liquid at room temperature and methane is gas gas at room temperature right just because it has more chances for those Vander wall forces just for that very slight very instant electrostatic attraction that happens between the two molecules right like I said very very small interaction but that's why one is liquid one is gas anyway it only happens between nonpol molecules well maybe not only it happens when we think of vander's interactions I think non-polar interactions so yeah it happens pretty almost exclusively non-polar interactions so anyway at the time of finishing this it is 10:30 at night and this oh and the Wi-Fi went out again okay oh there it is back again okay this video has run along for almost two hours at this point so my advice to you all is to just take what you need right if you have trouble with bonds I had entire section on bonds if you have TR if you're having trouble with subatomic particles I have an entire that was at the beginning of the video right everything that you need to know for the exam is here with the exception of like some of the uh um like domain stuff some of the anal Kingdom stuff everything else that you need to know everything about the atom that you need to know is here so in any case I hope you guys enjoyed the video um it was very long but I really hope that it was helpful and that this is uh this is going to be a resource for you um so yeah in any case I hope you guys have a good day uh take care or good night rather