Transcript for:
Understanding Atomic Structure and Quantum Mechanics

so before we get to look at the structure of an atom what exactly is an atom so we'll basically Define an atom to be a smallest particle of an element that has other properties of that element so I'm sure you've heard of what you call the periodic table of elements so on the predictable you find elements like sodium elements Like Oxygen so a smallest particle of any of these elements that can have all its properties okay is what we call an atom so if you get a small if you get an atom of oxygen for example it's very tiny you can't even get it in your hands so that's very smallest particle but it's going to have all the properties of oxygen is what we call an atom okay so now that we know what an atom is what exactly makes up an atom so it's made up of what we call neutrons there's what we call the protons and then it also it also contains what we call the electrons okay so I need to mention to say neutrons do not have a charge so no charge or neutral protons are positively charged electrons are negatively charged okay so that's what we basically need to know about an atom now what you need to understand is that in a neutral atom in a neutral atom we expect that the number of the neutrons is equal to the number of the protons sorry not necessarily neutrons the number of electrons sorry so the number of electrons basically are equal to the number of protons so what exactly am I trying to say so what I'm trying to say is the fact that if you look at sodium only predictable you find that it's got 11.3 so I need to mention to 723 which is a bigger number represents what we call the mass number and then the 11 on the bottom represents what we call the atomic number okay what exactly do we need to know so what you need to understand is when you now look at the structure of an atom and not too much what we call the nucleus so in the nucleus that's where we get to find the presence of the protons and also the neutron so I said neutrons do not have a charge and then we also have what we call the shells so now the shows which Salon the nucleus basically the electrons which are negatives okay that's how they are they're found so let me present them in a better way servos negatives so I've done something there by a tree If You observe I've put two electrons and then I've also put two positives inside there so that's the point that I was trying to make this the number of protons the number of electrons in a neutral atom are the same now assume we have we only have a single electron on the on the shell that tells us to say that we're going to our Nexus what positive so that makes the atom to be positive okay so at least we were getting there so understand over as we begin to look at the bonding and whatnot but basically you have an idea of the structure of an electron basically gets to come out so I believe you have an idea of what we call the electron configuration so let me try to give the lectin configuration of the sodium that we have in this case so we do know that every shell must have electrons so how many electrons is the shell supposed to have so one thing that we need to take note of is shells that are closer to the nucleus occupy or accommodate less number of electrons has compared the ones that are harder as we can see as you begin to draw them the ones that are coming out are actually larger so they are actually even gets documented more electrons so this is the way they accommodate electrons the first one occupies accumulates a maximum of two this one the second one that is eight begin to move so what formula exactly are we trying to use there so it's this formula so the first one web is n put a one you get two the second one put the two two squared multiply by 2 that gives you eight the third one put a three it would be nine times two so that's that's supposed to be 18 sorry put a 3 there put a four what do you expect to have four square is 10 so you have 82. so that's exactly the way we expect the shells so writing electron configuration in terms of the shells would give us two from eleven so this number which is atomic number represents the number of protons present in that atom okay now we've stayed for a neutral atom because the electron configuration represents another electrons distribution so we expect to have the same number of electrons for a neutral atom buttons so out of 11 you move two yeah remaining with what with with nine now we've seen that using our gender formula which is to N squared the second image level if you put the one that is n you find that it pies the maximum of eight electrons so you now have used 10 electrons out of 11 remaining with a single one so you have no choice but just to put it in the fade shell okay now under the statue of atomic structure at this level will be required to present our electron configuration using the orbitals okay so how do you get to do it so we understand that we have vertical the s p d f these are the kind of orbitals that we have so I'll just go direct and give the presentation I'll explain later how we basically get to go deep in terms of giving the election configuration so I'll say one is two to S2 p 6 3 is 1. so this is representing the the second image level the first energy level the fade so that's how I've distributed the electrons if you can see let me use the different colors that you're able to see properly so the two electrons are here the eight electrons are shared between the S and the p the one is in the Tilted energy level so that's just an idea of how you get to give electronic configuration okay using the spda4b2 so understand basically what the orbitals are later so we are going to talk about the Bose atomic model this is a very famous atomic model because it's very useful and very applicable most of the calculations that are performed under atomic structure are based on the same model okay so looking at this diagram it basically summarizes the things that we need to know about positanic model so according to Bo basically Anatomy is made up of a small nucleus which is of course positively charged as you can see in um in our diagram here you're able to see to say if you look at this nucleus it's very very tiny so what DOTA is there Representatives the positive insight there that's what the Bose atomic model tells us it also tells you say that it is of course surrounded by the negative electrons moving around so again if you look at the diagram that we have so these are made up of electrons that's what Bose so they are actually it's made the nucleus is surrounded by the the shells made up of electrons and then the other thing that would have to know is that the electrons that are located away from the nucleus has got more energies compared to the ones that are near the nucleus so that emphasizes on the aspect of the energy levels okay these shells are also known as the energy level energy levels sorry so the ones that are closer to the nucleus have got lower energy so in short for example this one this is bigger is smaller than than the one that is smaller inside there that's what both model tells us so in summary or more in detail actually if you look at this postulates that's what they tell us okay so I'll read through the first one says in an atom electrons of course the electrons are negatively charged they revolve around the positive recharged nucleus in a different circular path called orbital shows okay so it is all just talking about the diagram that is there okay and then the second post rate is that each orbit or show has a fixed energy and these circular orbits are known as orbital showers okay the third one tells us that energy levels are represented by the integer so we know what an integer is right okay so the first one is represented as one the second one two as you can see on our diagram there so those ones are known as a quantum number so we'll talk later about basically how you get to look at the concussions to deal with your quantum numbers okay so what integer n represents the energy okay so the bigger the integer the bigger the energy of that energy level okay so this range of quantum numbers starts from the nuclear side with n is equal to one having the lowest energy level of course we understand that we say the one that comes immediately after the nucleus is actually has called lowest energy when you begin comparing with the other energy levels so the a bit n is equal to one two three and four assigned letters okay klmn shows so the first one is called the N is equal to one it's called K so you're able to remember that so and when an electron attains the lowest energy level it is said to be in ground steps okay so an electron with the lowest energy is said to be in the ground effect the electrons in an atom move from the lower energy level to Iron Age level by gaining required energy and of course the opposite is true what that tells us is if you have an electron in the first energy level for it to go to a high energy level we've saved the one that is smaller or the one closer to nucleus has got lower energy so for each to move to a one that is outer there it has to gain energy that's basically the last point they're saying and of course the opposite is true for an electron to move from the outer energy level to go to all that is inner or closer to nucleus it has to lose energy okay so all that can be summarized by the simple calculation that we're going to be dealing with when you begin studying the transition of of electrons so you look at the use of this formula okay so when you talk about uh the final energy level and then subtract the initial so that basically summarizes everything that you basically get to deal with here so let's say you have a transition of an electron from the fourth energy level two the second energy level you would have to substitute there so that would be 4 squared as if oh actually we find one in this case as we are going to to is going to be two and then the initial one was four so you have one over four minus 1 over 16. so you understand that one over four is bigger than 1 over 16. so in the bracket say if you get to subtract you basically get to have a positive solution multiply by the negative that is there it remains a negative so which tells us to say that the negative represents loss in energy okay so the opposite is true if it was moving from 2 going to four you'd get a positive answer telling to say the electron had gained energy and then of course in conclusion you can talk about the limitations of both model okay so these are the limitations of the Boss model of an atom it failed to explain the ziemann effect it failed to explain the stack effect it violates the SN becomes the 10 principle so if you don't know about that you can watch our video about that you'll be able to understand what you're saying because and certain principle tells us of course to give you an idea is if it's if you basically know the position it's very difficult for you to to know how fast it's moving okay so it's either you know much about this position or you know much about this velocity or its momentum so it could not explain the Spectra obtained from the larger atoms so this that's it about the Boss model of an atom we're just going to talk about waves or of course within the context of chemistry so what exactly is a wave so we understand that a wave is a repetitive disturbance in the medium that card is energy so we've brought that definition from from physics okay so this is exaction example of a wave if we go into physics we understand that this is a an example of a transverse wave okay so there are waves like vibration that are like this those ones are said to belong to dinner okay but of course we'll not talk about that in detail this is not physics we will stick within chemistry okay so a few things that we need to understand from our definitions we are saying however is the repetitive disturbance in a medium that carries energy so repetitive means uh periodic okay so as you can see there is repetition of same movement okay that is what we call repetition or periodic okay then it carries energy as well and then it's also in a medium so a wave can be in air it can be in water so all that it depends so in physics you go into details how each medium gets to affect the the wave okay so of course correction on the sparing they are supposed to be repetitive so it's an eye missing there okay so what are some of the properties that we need to understand about a wave so If You observe this initial starting point but initial starting point to that other point okay so there is what is what we call the wavelength okay that is the wavelength now before we get to talk about the wavelength this maximum highest point on the top including that one these points are called traps so a trough so if there are two traps then the ones on the bottom are referred to as the crescents so the cresets okay okay so just a quick correction on the on this part you know these things get mixed up so the top parts are called the the corsets then the ones on the bottom are the ones we call the troughs that's what you need to understand now the wavelength that I've talked about from this point at that point B that is the wavelength so the wavelength can also be measured as a distance between two troughs okay so the distance from A to B is the same as from this point to add another trough equally if we try to observe from this question to the other question it is the same to all the other distance that I've talked about so all views can be labeled to be the wavelength so with not to have length using the Lambda that's symbol then measuring from this initial Point going up or even down there so we call that the amplitude so that measurement either fat does the amplitude so we can Define the wavelength to be the distance between two successive identical parts of the wave so you can make you can also Define it to be in terms of traffic so distance between those excessive troughs the distance between two successive cassettes okay that is what the wavelength is now we've identified the amplitude how can we Define the amplitude so it is a maximum displacement from the neutral position so the maximum displacement going up by the wave is what we call the amplitude okay so whatever thing can we look at under the web for parties okay looking at the diagram that we've come up with uh We've identified the properties that we're able to tell from there now there's some other properties I would have to understand whenever we are talking about the web we've already talked about the wavelength to be with distance between two identical points of the wave or if it can be trough Square sets okay so the amplitude is a maximum displacement by the way from the neutral position now we have a new 10 frequency how do we get to Define our frequency so frequency goes with frequent how frequent is the wave so we basically get to Define frequency to be the number of repetitions per second number of repetitions the second that is what frequency is so one thing that I want us to understand is looking using the same example of the transverse wave like this and then I get to draw another wave like this So You observe a term that is in yellow is more frequent than the one in Red so we can say that the this webinaro is has got out has got the r frequency that's the basic idea that we're trying to to say now again I'll draw the same setup that's a wave and then we have another wave like this okay so of course we understand that wavelength is the distance between that so in this case it is the distance between those two points of course you can also use the crosets but I'm using the traps okay so what exactly are we trying to say so if you check the wave on top You observe that wavelength is actually what shorter than the one down it is actually what longer but in terms of frequency which one has got the r frequency what Ayah frequency it is more frequent then the one on the bottom has got low frequency because it is the repetitions I feel so in addition to frequency we can also talk about uh the period okay so we can talk about the period as the time it takes between two presets or two traps or you can also Define to be the time it takes to complete a wavelength okay so to be more specific if you're looking at the diagram how long you are taking the computer wavelength the time it's taken that's what we call a period of of a wave so the period is noted as capital letter T frequency denoted we can denote it using the letter V of a circle Atomic extraction okay so looking at the what we have on our diagram we are trying to observe to say if you look at the wavelength when the wavelength is shorter we've seen that the wave is more frequent so that is high frequency and then of course this other diagram we've seen that lower lower frequency but the low wavelength is longer so that tells us to say that the frequency and now I'm saying frequency is going to be noted by a letter v so frequency is industry proportion to the wavelength okay so for the sake of atomic structure we use a constant of speed of light so if there's one we can put the C to form an equation so V is equal to the speed of light over wavelength so what C is our constant which is the speed of light 3 by 10 to the power 8 and then that is our wavelength so that is going to be very useful make sure you take note of its equation okay so that shows industry proportionality between the two queens and the the wavelength if one is longer that one is going to be lower that's the way it works so that's why if you go to You observe a spectrum things like the gamma Las or the wire raised X Lays the UV the visible light We Begin going this side towards the radio waves so you find that these ones I've got I frequency but they've got lower at the ones on the leftmost the wireless the x-rays the UV of course visible light so going towards the left the highest frequency shorter sorry yeah shut out wavelength then as you go with your side the wavelength begins to increase becomes longer and then the frequency is low that is exactly what you'd have to understand there so that is in this industry proportionality so of course I would have to mention to say the frequency is also industrial portion to the period you can also know that okay then velocity we we've already been exposed to the velocity so velocity within the context of if you're talking about velocity under linear motion how do you basically get to Define velocity diversity is a lot of change of displacement so we can Define it the same way the rate of change of displacement of the wave that is uh the velocity and then the wave number I want you to number 12 number is basically given as one of the wavelength okay so one other oil length gives you the wave number okay so these are the things that you have to know and uh atomic structure when you're talking about the wave properties okay so we just have a question to practice standard blender about so far another word properties so feel free to pause the video and try to attempt the question so we have write emitted from anatom with a wavelength of 778 nanometers we need to find this way of number and frequency okay so quickly I'll go straight so we save the web number is given as 1 over the wavelength so the wavelength has been given now one thing that you need to notice the units the SI units for wavelength are meters so they have to work with 15 meters okay so area under measurements we said we can convert Nano Nano is the same as 10 to the power negative 9. that's what Nano means and then you man with meters are okay so quickly we have 1 over 778 times 10 to the power negative 9 in meters so 778 times 10 to the power negative 9 divide into a one so the answer what I'm getting is uh 1285 so it's actually one million one million 285 3 4 7. so a lot of numbers now looking at the question we have got three significant figures so three significant figures considering that each of your answer would be much better so let's consider two significant figures so we have one two Andy three okay now looking at the next number it's a five so we'll let it be one so since it's a five you can add the one that it would be 129. okay so I'll say 1.29 now we add a million so that is point zero so one two three four five six so then the pass Six foreign so it will be meters negative so it becomes our wave number that's exactly how you're supposed to answer that question now the second part of the question is asking us to find the frequency so remember we said frequency and wavelength for industry proportion so therefore frequency is going to be the speed of light as our constant divided by the wavelength the speed of light is 3 by 10 to the power 8. meters per second divided by the wavelength the wavelength is 778 so use that is what times 10 to upon negative 9 because we want it in meters so 778 times 10 to the power negative 9 being divided into three by ten to the power 8. so I'm getting 3.8 six so I've gone directly stem around 3.86 three sniff configures times 10 to the power 14. so the units are is the same as one over a second so what those are the units for frequency and that's exactly how you get to go about this okay so we talked about Planck's quantum theory so having an idea to say if you have an atom so we expect Anatomy to emit energy as well as capable of gaining ending so focus more on the emission of energy so radiant energy which is of course emitted uh has got wave kind of properties that's why we talked about wave properties this area record because we needed to understand exactly how waves gets to behave okay so there were theories before Planck's content Theory to say radiant energy was emitted continuously just like we saw the wave okay so now pranks quantum theory came to disregard all that okay so according to Planck's uh quantum theory it basically tells us that energy is not emitted continuously in steady different atoms or molecules can emit or absorb energy in discrete quantities so it's not that energy is going to either be emitted continuously or gained continuously but instead different atoms or molecules can emit or absorb energy in discrete quantities so we have a new team that is introduced to us discrete quantities only so it's like you have a portion gained and then another portion after the same period of time just like that instead of it being continuous again or continuously lost that's what basically the quantum theory tells us so the smallest amount of energy that can be emitted or absorbed is known as a quantum okay so the smallest amount of energy that can either be emitted or absorbed in this discrete quantities is called a quantum okay and then finally first understand everything the energy of radiation absorbed omitted disease directly proportion to the frequency of the radiation so this introduces us to a new formula that we have to understand under the study of Planck's quantum theory which is at the energy of a photon is equal to at so what you're trying to understand is the energy is directly proportional to the frequency so the I have a frequency of the radiation that is either being absorbed or emitted you expect that the frequency the energy is going to be either more energy is going to be gained in terms of absorption or more energy is going to be emitted depending on the frequency that's exactly what this formula tells us and it's very very important and it's going to be very useful for this under study of atomic structure so this requires us now to understand exactly what the edge stands for so the H stands for Planck's constant which is a value but you are supposed to know but in most of exams they get to give you but you have to know it's not even very complicated it's a 6.626 by 10 to the power negative 84. Jaws second okay so that's it about the Planck's quantum theory so in summary what we've said is different atoms or molecules can emit or absorb energy in discrete quantities only of course the smallest amount of energy emitted or absorbed is known as a Quantum so this formula is used to calculate the energy of a photon okay so we now look at practice questions in regards to Planck's Constant and the prime time Max was uh you know quantum theory so we came up with an equation to say according to Planck's constant he actually told us to say the amount of energy emitted by photon is direct proportion to the frequency other frequency more the energy will be emitted or absorbed okay so if you look at the first question it says a compound emits like having a wavelength of 300 nanometers what is the increment of energy meter so we're trying to find the energy that was emitted we've been given the wavelength we've not been given the frequency so what we basically get to do so we know that will also area said the frequency is industry proportion to the wavelength so this equation can also be written as the web is frequency we can put speed of light over the wavelength okay so at this point what can we say so we can easily get to substitute right so say the energy of the photo is going to be equal to so Planck's constant is a known constant which is a 6.626 by 10 to the power negative 54. I do understand you know what the units are jaws second and then we need to multiply by the speed of light which we know is 3 by 10 to the power 8. meters per second so I can write that if it in a more organized manner so the second means divided by a second and then all this divided by wavelength so wavelength we need to make sure that it is in meters so Nano means by 10 to the power negative 9. so we have meters now so some of the units would have to cancel meters to cancel the seconds will divide so ultimately will be able to see that actually this is dimensionally correct because the units of energy should come out so we have 6.626 by 10 to the power negative 54. multiplying by three by ten to the power 8. divided by 300 by 10 to the power negative 9 okay so after dividing the answer that I'm getting is uh a value of six so or out of 6.6 2 6 times 10 the power negative 19. this is obviously because 300 to 300 are matching up right the point negative 19. now the units Jaws so looking at the question there was only a single significant figure so it's even okay rating an answer as you can just consider to significant regards for the sake of being a bit accurate 6.6 by 10 the power negative 19 Jaws that is the energy that we expected okay we have another question which says calculate the energy of a photon of light having a blank for that so if you've given us the wavelength as well they also want us to find the the image of the photon so this is a simple and straightforward feel free to basically pause the video and try to see if you're able to get the answer okay so basically go Direct um yeah the one has to determine the energy of the single photon okay now how basically do we get to to do that so the same formula applies since we have been given the wavelength it will be instead of putting frequency to B C over a wavelength software performing oil calculations there you'll be able to get an answer so take that as a practice question so we've already seen the need of this formula because it's coming from maximum Planck's quantum theory we said energy is energy emitted absorb is directly proportionate to the frequency of the light or photon okay now I want to determine the energy of a more of a fortune so this formula is only for energy of the four term so substituting the information that we have our energy of a fortune is going to be Planck's constant okay okay so units are just seconds multiplied by speed of light the units are meters seconds we are dividing by the wavelength um five eight four times ten to the power negative nine because one take the nanometers to meters so the units are meters so meters second women with a jaw so remember this formula is image of four term so grab your calculator and perform the calculations there 6.626 by 10 to the power negative 54. multiply by three by ten to the power 8. divided by five eight four by ten the power negative nine so the value what I'm getting is three point four zero four by ten to the power negative 19 Jaws so remember this is the energy of a photon now in this time around the one that's determine the energy of a mole of the photon so each time the anything any form of calculation can be reduced with a more so we know that we're dealing now with our with Avogadro's constant which is 6.022 by 10 to power 23 okay so more so in this case we are dealing with a photon so and more of a photon should have so how can I put this let me put it this way pay every more of anything this time around it is 6.022 by 10 to power 23 what we're studying is we're looking at the energy stop every more of a photon we should expect that amount of energy I think that's what we'd have to understand whenever the language is for meter so now I want to determine the the energy that is going to be Associated every more how busy do we get to deal with that so I'll start it like this so we have six I'll get the answer first of all 3.4 by okay 3.404 by 10 to the power negative 19. that is Jaws so we have Jaws per reportum I want to find the answer or the energy of a mole of the fourth term more of a fortune so we understand that the formula Avogadro's constant is 6.022 right then the part 23. so it's always it's always be every more the every more they sh they pay every more there is that amount of that amount of energy okay so in performing our calculation our result is supposed to be in Jaws so Jose we have that number of photons per MO so a photons will go and then you mean with just pay more so at the end of the day we are just ending up multiplying the two so what answer are you getting so picking up this number of new configures I'll go for three so 2.05 by 10 to the power five just bear mom so that's how you get to determine the energy of a more of a photon using the maximum Maxwell planks quantum theory let's get to talk about the for the electric effect so photoelectric effect it involves emission of electrons so we have emission of electrons from my metal surface when light gets to strike so when you have a metal surface and then you have light striking this metal surface like that so emission of of electrons is what we are defining to be the photoelectric effect so we've seen that there is first of all light striking and then we are seeing the emission of electrons so emission of electrons from that metal surface is what we are calling the photoelectric effect okay so very few things that you'd have to know about what electric effect okay what gets together how much of the electrons are are being emitted from that metal surface okay so the first thing that you'd have to know is uh you can tick down this this is very important no electron emission so there's no electron emission so write this in full form electron no electron emission below the threshold frequency so very short so it's threshold frequency so there are no electron emission below threshold frequency so there's a new term called threshold frequency so you need to know what the threshold frequencies uh the minimum frequency required for electrons to be emitted so you understand that before electrons can be emitted from metal surface there is a certain amount of energy that is required to kind of unbind them from because they are attached service need for energy required to remove them so bad energy is what we are calling the threshold frequency okay of course we understand that the formula itself is uh that so the energy required requires a certain minimum of frequency so that's what we're calling the freshwater frequency threshold frequency is a minimum minimum frequency required to emit electrons so the first point what we are noting about for the electric effect is no electron emission below threshold frequency so when you are striking a metal surface with a light with lower frequency or a frequency below the threshold frequency will be no emission of electrons expected from that metal surface that is the first point the second point is the amount of electrons emitted above the threshold frequency so I'll go again the amount of electrons emitted above so the amount of electrons so I can say emitted above the facial frequency are directory proportion to the intensity of the light so I believe you understand the intensity of light when light has got high intensity and low intensity so what this tells us is if the light that you are using has already more than the threshold frequency as you begin to increase its intensity you expect that more electrons will also be produced so increasing the intensity when a light has already made the pressure frequency increases the amount of electrons being emitted and vice versa if you reduce the intensity okay despite the light being above the threshold frequency expect the number of electrons being emitted will also be reduced and then the other point the third point under the photoelectric effect is that an increase in the intensity of light so an increase in the intensity so you can also decide to increase the intensity when the first word frequency is not met so an increase in the intensity of light below the threshold frequency does not produce any electrons okay so whether I get increase the intensity of the light provided the pressure frequencies is not met or it is below the threshold frequency there is no emission of electrons even if even as you get to increase the intensity of that light okay when finally the thing that you'd have to notice for number four it is number four for the frequency above so for the frequency that is above the threshold frequency the kinetic energy of the electrons gets to increase with the frequency I believe you understand what that means so that will introduce us to a formula that is very important when it comes determining the kinetic energy of the the electrons that are emitted from a metal surface during due to photoelectric effect so the kinetic energy of the electrons emitted is given us a difference between so I'll explain this formula so this party is representing the threshold so the V note that is a threshold frequency so a threshold frequency will be able to give us the amount of energy required to remove those electrons from the metal surface so I was talking about unbinding of electrons so what unbinding requires a certain threshold frequency so we subtract that energy from the frequency of the electrons okay so the frequency of electrons after emission minus the initial gives us the difference is the energy the kinetic energy or the energy that is leading to the motion of those particles of course understand that H is a Planck's constant which is 6.626 by 10 to panic at effect form so in a case where they give you the kinetic energy and ask you to find the frequency of the light after emission you can substitute provide will give you the threshold frequency and of course in a case where I will give you the final frequency and also the kinetic energy also able to find the threshold frequency or in a case where they ask you to find the kinetic energy of electrons after emission given the final frequency and the threshold frequency you should be able to use this formula and apply it it's very useful very applicable under the studio for the electric effect and of course this summarizes everything that we you have to know under photoelectric effects so with particle drity is a concept of what quantum mechanics which explains that light behaves buffers as a particle as well as a wave so in cases where they ask you to say what process is able to describe the way of nature of of light so light undergoes photoelectric effect you can talk about absorption and also emission of atoms and then as a particle light is about to undergo diffraction and the interference so there are a few things that we have to know we're not talking about light the wave and then when you're talking about light as a particle so that we get to derive the formula so we understand that according to instant theory of relativity their energy is related to Mass and the speed of light using that very famous formula okay so this formula is representing light as a mass now we are also looking at light to be a wave so we talked about Planck's quantum theory well relative energy to be equal to Planck's constant multiplied by the frequency okay I'm sure you both remember that okay so we also know that the frequency can be expressed in terms of the division between the speed of light and what and the wavelength okay so so far we are on the same point right so let's try to equip the two formulas we see what we're going to have so energy is the same so just get the right hand side of the two formulas so we have the mass speed of light squared is equal to Planck's constant speed of light over the way of length so c squared means c times C so one can go away okay so cancel and see with other C so you mean with uh m c B is equal to that over the the wavelength okay so we're able to move we're able to move so not at the speed of light represents the the velocity right the speed of light represents the velocity so for the sake of generalizing it because of course speed of light just represents when I'm dealing with a vacuum and whatnot so I can write it to be MV is equal to Planck's constant over the wavelength and then we can make the wavelength to be the subject by Crossing or not playing so we have our wavelength being equal to Planck's constant over Mass multiplied by velocity so at this point this is what we call debris the Blogger wavelength so it is basically Planck's constant divided by momentum we know momentum is a product of mass and velocity so this is a very useful formula and we'll be using it in a case where they ask us to determine the debug the wavelength okay given that they've given us the velocity and of course the mass so this is what we've particularly deals with basically so the concept itself identifies light to possess both wave and particle properties okay so from that comes this formula of debuggery wavelength which is a very useful calculation and their atomic structure I'm sure your weight of the hydrogen Spectrum so what exactly is the hydrogen Spectrum so the many arguments is that when you get to path an electric discharge through a gaseous hydrogen molecule so another cut is in gaseous state if you get to pass it through an electric discharge or if an electric discharge passes through this hydrogen in gaseous state so you expect that there should be animation of radiation so what hydrogen gaseous state to emits radiations so in addition to what so the hydrogen emission spectrum will consist of radiations of discrete frequencies okay it's not like it's going to have identic or radiation but it's going to be of discrete frequencies so that means that a lot of things that are rejected okay so get to talk about all those things in details so from that basic argument we need to understand that if you have an atom okay and then it has got electrons so electrons are capable of getting excited to get to Ayah energy levels and vice versa the opposite is they are also able to move from the lower from the Ayah to the lower ones by losing energy so there's one which is involving excited state is gaining of energy getting from moving from Ayah to Lawrence is losing energy okay that's basically what gets to happen okay so very few things that are very useful understood the atomic structure but you basically have to get to know so whenever you have the first energy level there whenever I have a first energy level so if you have the movement of electrons from other energy levels to the first energy level okay like that these are just some of the examples I can I can give maybe let me let me talk of one there let me talk of one there one there and then one there okay so let's say we have a movement of electrons from all those energy levels provided they are coming to the first shell the first energy level you need to know that it's they are referred to as lime and series okay so Lyman Series so these were just the names of the scientists that were discovering them so the second energy level let's say to somewhere yeah so you can also have the movement of you know these uh electrons from elsewhere so you may have from the FED energy level from the from the fourth and so on and so forth so this is the first second energy level so remember the shows are in circular form but I'm just trying to draw them too short but it makes sense so the first one I've drawn you straight and the like that's not exactly what I'm doing and then we can also consider a third one so I've not given you a name for the second one right so any transition associated with the second energy level referred to as biomassilies okay so if you have an electron moving from a fade going up coming into the second image level it's basically I referred to as well Mercedes and then you can also consider the third one so you can also have a third one can consider fourth one so if you talk about the third one associated with the third one is uh the passion cities so passion savings and then so that is uh just put it there and then the fourth one associated with the fourth one is uh it's also called brackets cities I mean finally the fifth one is Zippy funds signals so if you have a movement of electrons from Aya to the fifth one which is basically refer to Zippy funds okay so these are the hydrogen sillies that you have to know when it comes to the transition of electrons okay now apart from that the other thing that would have to know is that there is the original spectrum that each transition is associated with okay so when you are talking about emissions so it's also true that when you have a mission of the lineman series from the first energy level going to our energy levels okay let's say you have an electron being emitted from the first energy level to a second energy level or any other energy level going to the third fourth third and fourth so that is still referred to as Lyman series now it is associated with ultraviolet light so in such a case what we expect is what is emitted is UV ultraviolet okay now emissions associated with the bow Mercedes moving from the second energy level going to our energy levels when electrons are emitted like that from here to there okay so that is associated with visible light okay Bowman city is associated with visible light so this bright is what is emitted when electrons are moving from the second energy level and then when electrons are emitted from the Third from the third energy level so the third energy level emitted from the Third from the fourth going up it's all in flooded up to the P fund Series so the only unique ones are emission from the alignment series emission from the bar Mercedes which is the first and the second and then fade to the fifth if they emit so that is very easy for you to remember the kind of Animation associated with every kind of a series when it comes to the Irish inspection okay finally the other thing that we have to understand is when it comes to the emissions we need to understand that there is an equation associated with determining the wavelength okay if you have a transition so the way of number is basically equivalent to relive x constant and then you have you have transitions N1 squared minus N2 squared so in other terms what we're trying to say is if you have a transition from that energy level squared to the other energy level squared you should be able to use this formula to determine the wave number now the wave number we know that is one divided by the wavelength so you should also be able to determine the the wavelength using this very formula so consider a case where you have a transition of an electron from the first energy level to the third energy level so you have to substitute 1 squared as your initial and then your N2 which is like a fit so like big constant is a constant of you're usually given value during assessments 109677 centimeters negative okay so you are capable of converting value to meters okay but usually preferably we use it and uh in centimeters then we can get to convert our solution later to meters okay so this is basically a various formula when it comes to determining the wavelength associated with transitions of electrons from a single energy level to another energy level equation so we know that from our previous video where we talked about the hydrogen Spectrum we know that the wave number is equal to the library's constant and then of course in the brackets we have 1 over the initial energy level minus 1 over the second or the final energy level squared so light big is constant we know it's always going to be given to us so it's 10 973 731.6 in meters negative so we have wave number on the left hand side and then in the brackets lineman city is associated with the first energy level okay of course you need to know about muscle is the second third is uh associative brackets with passion and then fourth is bracket finally the fifth is uh P fund all that so you have one over one squared as your initial and then your final is three since it's going to fade energy level that's the transition of an electron from so of course you need to picture this in mind this is animation so having an electron moving from the first energy level all the way up to the FED energy level so expect that is the gain of energy there so where we have our wave number wave number is one over wavelength so it is equal to minus one over nine which is obviously going to be eight over nine multiplied by ten nine seven three seven three one point six okay so the answer I'm getting is 9.754 by 10 to the power 6. meter is negative so we just have to divide uh if you cross that multiply you end up dividing one by the answer that we found to get our wavelength so our wavelength easy 1.025 by 10 to the power minus seven in meters so that is how you apply the Library equation performing calculations all right so let's try to talk about electron transitions of electrons so at this point I believe we do understand that if you have an atom okay so consider this to be the shells all right so if an electron is moving from an inner energy level going to the outer energy level that is referred to as excited state of an electron so an electron is excited it gains energy and goes to our energy levels remember from the start of the study of atomic structure we did make a statement to say energy levels that are closer to a nucleus I've got lower energies convert the ones that are outer or further away from the nucleus so in this case this energy level let's say the first energy level the second and the third the first energy level has got less energy as compared to the second and the third so for an electron to move from the first energy level to go to any energy level outside it's basically going supposed to gain energy okay and of course the opposite is true for an electron to move from outside energy levels to the enons they're supposed to be loss of energy so what is being unexcited okay so what kind of understanding from the previous video where we talked about the library equation we saw that one over the wavelength was basically equal to the liabase constant multiplied by 1 over the initial energy level minus 1 over the final squared energy level so all that that was the formula we're using to find our our wavelength okay so how useful is that equation so now in this video we basically want to talk more about how we get to find the energy associated with the transitions we saw how we got the wavelength from the equation so basically by knowing that from the buzz model we came up with an equation which was involving Planck's Constanta okay so that's equation allowed us to build an argument knowing that we know that the wavelength is industry proportion to to the frequency right so that frequency gave us a speed of light over the wavelength so this is another equation that we came up with okay so energy is same as pranks constant speed of light over the wavelength this is another use of equation that we came up with so now in this equation if you try to make wave the subject you find that you end up with HC over the energy okay so now look at this part this part is the reciprocal of the wavelength so reciprocal means it's what reciprocal means it's the opposite so I would have to exchange the two so if I put say 1 1 so I end up having one over wavelength is equal to 80g over HC so on our left hand side we put our energy of Planck's constant speed of right is equal to live X constant so at this point what basically do we understand so our goal is to make energy subject to the formula so don't forget whatever is in the brackets it is there so we'd have to close our multiply therefore energy is going to be equal to live x constant multiplied by Planck's constant multiplied by speed of light whatever is in the brackets remains as it is so now you know that lipx constant is equal to one zero nine seven three seven three one point six in meters minus and then you know Planck's constant is 6.626 by 10 to the power minus 54. you know what speed of light is 3 by 10 to the power eight so I'm applying all these values okay so what answer are you going to get so the value what I'm getting is 2.18 times then the power negative 18. that's the answer that I'm getting personally so I would have now substituted the final equation to say the equation that is going to be very useful is 2.18 times 10 to the power negative 18. as a constant and then in the brackets we maintain what all there so we have one over the initial squared 1 over final squared so what is in the brackets is denoting the energy levels that we are dealing with okay so consider an example where we get to where we are asked to find the energy that was required to move an electron from let's say the second energy level to to the third energy level so in such a case our energy is going to be 2.18 times 10 to the power negative 18. substitute the initial as 2 squared the final or three so multiply our constant by one over four so we have one over four minus one over nine so the answer I'm getting for our energy is 3.029 times 10 to the power negative 19. now you ask yourself a question the answer is positive in Jaws why because it was excited and the electron was excited from the second to the third energy level so that's why the answer is a positive the opposite is true if you try to put a 3 there and then a two there you find that you end up having a minus a negative answer which shows that there was loss of energy for the electron transition we have a very interesting discussion about orbitals and they look at how we basically get to give electronic configuration using the orbiters an example what I'm trying to say is if you look at uh carbon we know Carbon has got six electrons in its neutral state so the electron configuration is all that okay so 2p 2 what's electron configuration of couple okay now I want to understand how you basically go about giving electron configuration but um we also know that magnesium which has got 12 electrons can also be represented in this form using an opal gas that's also another way of giving an electronic configuration so this gets to represent what you call noble gas electron configuration this is just electron configuration using the orbitals so that's basically what we're going to study in this video so before we begin to or study on that we need to understand basically what an orbital is so so far anatomic structure we know that we have what we call energy levels or shells where we basically get to find the electrons now electrons are not necessary do not necessarily exist on the shows as we get represent them on these diagrams so an exact or a location where there's a probability of you finding an electron is what we call an orbital so an orbital you can picture it as something that is like a sub shell or it is part of an energy level so one thing that you need to understand about an orbital is that an orbital is able to accommodate the maximum of how many electrons two electrons maximum that's what you need to understand about a mobito so we have a few orbitals that we have to understand what you call the S orbital the p the D and if so commonly known as the spdf orbitals the S orbital accommodates a maximum of two electrons the p orbital a maximum of six electrons the D orbital a maximum of 10 electrons the F orbital a maximum of 14 electrons so if you've observed the difference of four electrons each now from the beginning we've made an argument to say every orbital occupies maximum of two it accommodates a maximum of two electrons so later on we understand as we talk about the quantum numbers to say a p orbital basically has got how many electrons has got subshells accepted we can think of anything that is called sub orbitals within it so these sub orbitals are the ones that have like two so it has got three sub orbitals that's why it's about to have six electrons the D has got four so basically not necessary four five sorry so it has got five so five yeah this one has got seven the first one has got a single sub atomic orbital that's why we have all these number of electrons okay so let's try now try to see how we basically get to present our electronic configuration how basically do we get to find the electrode configuration okay so this is a predictable this is like a skeleton of a periodic table so this is group one and group two these are the elements that are between group two and group 3 commonly known as the transition elements then here I have group three four five six seven and eight so I may find that hydrogen sometimes is classified to be part of group one sometimes it's just somewhere there and then of course in that first period there is also idiom there that's why I have tried to show it so there's idiom okay and then hydrogen somewhere yeah and then we can start with lithium and then all the other elements gets to go to move just like that so with this understanding of the periodic table the reason why I'm trying to bring this into picture is for us to understand the how we basically get to give our electron configuration so group one and group two I referred to as the S block of a periodic table so this is the S block three audio up to eight I referred to as the P broke what is in between here it's called the D broke and then what is on the bottom is called the F block so why are they called these names do they just like a sign where they just assigning Orlando only giving them so this is spdf I referring to the orbitals that we are from talking about so any atom or any element what has got the outermost orbital to be the s in such a case it is falls under the S block okay so I can give you an example of uh lithium for example if you look at Ricky and lithium has got uh three electrons atomic number three so it's electron configuration of course we've not talked about how we get to have it you find that these are the three electrons two in the first s orbital and one in the first in the second SLP so what is the outermost orbital so it's easy in the S block now considering an example of carbon I said carbon has got six electrons so we had two s one S2 to S2 to P2 so the outermost orbital is P so it tells us carbon is of course in the P block the same applies to all the other elements if you consider the transition elements try to write the electron configuration you'll be able to see that the outermost would be D if you get the ones that are below the F block you also have the same that's why we basically start from without understanding what exactly are we trying to say so you need to know this trend One S two s 2p so the basic argument is in the first energy level there's only one orbital remember with this formula that is used to derive the number of electrons and energy level is about to occupy so a first energy level you'd have to put the one that is in it will just be two the second energy level you have to put it to 2 square will be a four so the first energy level occupies the maximum accommodates a maximum of two electrons the second energy level maximum of eight if you continue substituting there put a three three squared it's going to be 9 by 2 8 10. you got the fourth one fourth square is 16 right 16 times 2 is 32. so this is the way the energy levels increase their accommodation they are about to accommodate that number of electrons respectively as we get to increase so with that kind of an understanding we understand as we proceed as we get to go down the number of orbitals get to increase by one so you see so 3s 3p so here I say this increases by one so it will be 3D 4S 4p 4D so it will not end I will also add 4f this is the argument that I was trying to make to say we get to increase add an extra of course we end at four well this is where we we get to have the maximum right for f everything else will just be following in that we can't have any other because remember we said spdf Atomic orbitals spdf electron configuration so how basically do we get to give electron configuration so move like this one is 2s 2p3s 3p 4S 3d4p5s I'm drawing the lines so this is the order that you get to follow so it the order when it comes to change when you reach at the D orbital okay the orbital so you can't move from 3p and go to 4S no and go to 3D you have to go to 4S so the basic idea is we have one s to s and then the lines are showing us you go to 2p you go to 3s and then the lines are showing as you go to 3p from 3p you go to 4S and then you get back to 3D you go to 4p you go to 5S so at this point we've already understood how many electrons each um each kind of orbital occupies so I've said s can accommodate to P6 d10 all that so you know if it's got a fortune so that is going to be very useful in our study of electron configurations now let's say they're going to August and see because what's going to begin happening in terms of you know we get to give electron configuration and whatnot so I did give you an example of magnesium so magnesium has got 12 electrons right magnesium is in group two which tells us say the mark the the outermost orbital is supposed to be the S since it's in the S block we made that argument from the start so what are we trying to say so if we try to give the electron configuration we have two electrons in the first sobito the lines tells us we go off to 2s it occupies a maximum of two accommodates a maximum of two and then we go to two future maximum of six so if you get to add these how many electrons that we used up from the twelve two plus two is four plus six ten so I'm marrying if two electrons according to the lines they show us from 2p you go to 3s how many electrons are remaining two with an example of mechanism we already seen that it is actually true because if we look at our periodic table we observed magnesium is in group two so the outermost shell of magnesium has got 3s okay so I want you to think very smart so if we are to reduce that to 3s1 would end up with sodium that is going to be very useful as we get to move so the way I think of this is the moment you get to period four it's like one two three are you able to observe that factor so that's the first period okay second third fourth so I expect that if I'm talking about the automotive here of potassium okay it's supposed to be four now I know that this is the first two groups are the S broke so supposed to be S so if it's potential it would be one because in group one if it's calcium it would be two that's the way it works okay now assume I basically get to move on to these transition elements so understand later we have to get to go about that now just taking you back to tier three so if we go to aluminum for example can we give this electron configuration so obviously we know that the last one is going to be this is the P block okay fronti from group three going to eight that's a p so obviously arminam is the first okay so group three is the first one in the P broke so since we are in the third period it's obviously going to be 3p and then one so this obviously is the outermost shell for aluminum okay I assume we are looking at sulfur you just have to count in the P broke one two three four so you end up having three P4 that's an understanding but I want this one of us to have and of course that is true so you've used up how many electrons considering so I've used up four electrons already so we know that it has got an atomic number of 16. so we expect that the other 12 electrons are shared starting from the first and you can prove that one is to 2s2 P6 3s2 counties two plus two four plus six then 12 16 which is true so with this understanding where we're able to predict the outermost shell Texas what we're now calling the noble gas electron configuration okay takes us to electron configuration so you've understood the importance of knowing the periods of the periodic table and also the importance of knowing the blocks of the periodic table we said group one group two that's the S broke this here is what we call the D and then that is the p and then this is the F block that is all that is very important very necessary for us to apply you know very important so one thing that I would want to take you back is if I go to the previous page here we're able to see that there's something that is strange in that instead of moving from 3p going to 3D we are actually going to to 4S so how exactly can we explain that how exactly can we explain that so I'll go back to periodic table and just try to give you an example about that why we are why that actually is happening so this is period one periods two tier 3. so I gave us I gave you an example of sulfur so I said sulfur in the outermost shell since when the P block is going to be p and then count from the first group which is part of uh remember this is all the pub right so group two is actually the first one so say one two three four so four so that is where Alpha is now assume why we wanted to proceed so instead of this being fossil it's supposed to be three because we're in the third period by the way so now assume we want to go to something the fourth period so if I go for Argon I'm supposed to count favor from solve for four five green six argon so argon is supposed to have three p six now what happens remember the moment I go to potential it becomes four S one made I go to calcium it becomes 4 is 2. that's the way it works now you'll realize that Scandium going this side is all involving the the timber so now they did broke very interesting parties since this is the Deep broke and then we know that this is the first Debro we're having remember from period one periods two tier three there's no deep Bro because there were no transition elements so it starts from there now if you go back to our lines there we're about to see that the first d block we have is the third deeper so that's why there's a bit of some lagging so if you are in the fourth period the D broke there is a three here in the fifth are period it's four so that what I'm trying to say is that Jim broke lags by a one like that so if the seventh you'll be at six so without understanding we'll be able to see that as you get look to scan Scandia Scandia move 3D one that's exactly what we mean that's one thing that is very important for us to understand and that's why there's this kind of of lagging here from three picots to OS again come back to 3D now you realize that as you go back after this D broke you now have to continue before now before applies to the p and the S so you've been the what you'll be back to the 4p which is basically true if you look at this from 3D you go back to 4p itself now after before p You observe that after you're done with this 4p you're going in the fifth broke periods so the S will apply so it will be 5S which is exactly what we have from 5S you go back to D broke right so which will be the four that is basically something that is true and very interesting okay that is very simple for us to understand now that's going to be very useful as we get to look at giving electron configuration using the noble gas electron configuration okay so let's try to look at certain examples about that um so I'll start with a very mechanism that we looked at so if we see magnesium this was this electron configuration so how can you give this electron configuration using the noble gas electron configuration this is also called the shorthand uh electron configuration or notation so if you look at it what is going to be very obvious we are going to be working with um with the noble gases so a noble gases are these ones in group eight starting from idiom all the way up to somewhere that I don't know what I don't know the name but element on the bottom there we can start by looking at lithium even before we go to magnesium so if you look at lithium it's in group group one and then it's in the second period so we have to get the noble gas before that period where the element is so in this case lithium is in PH2 so we need to go back to field one what was the last noble gas it was idiom so the way you give is selecting configuration will be idiom and then now we need to identify the outermost shell so you realize that since you're in the second period is two and then this broke is the S block so it's a s and then lithium is the first one so it's one if you're looking at belly Dam it is going to be 2s2 so this is exactly the electron configuration for lithium using the noble gas electron configuration in a case where we write it in a normal way would expect to start from one S2 s now it has got an atomic number of three so obviously just end up with a one so the main idea is what we're trying to say is this first part has been presented using the noble gas since the number guys add two electrons an atomic number of a two that's the way it basically gets to work when you're looking at the noble gas electric configuration now again um giving you an example of uh of magnesium if you check here magnesium we are ending with 3s2 so we can represent all this first part using a noble gas so if I take you back so magnesium is in the third period so we can basically use the previous period which was uh phd2 the last number over 10. so that's right neon put it in these brackets and then the first broke is the S and we are in the third period so set three s now count from the first one two so it's 3s2 now this is basically true this is indeed the last uh orbital even after following our order so now this is the full electron configuration this is a noble gas electron configuration because we are using a noble gas to present the electron configuration and of course you realize that this is a bit faster it is faster indeed when you look at very big elements now let me try to make a bit more interesting and look at something that is a bit bigger so let me consider sulfur again so far so if I trade a little configuration of sulfur start counting the electrons you have something like that 26 to S2 and then 3p so one two three four so what is the electron configuration of sulfide in four now if a number gas electron configuration all you just have to do easy look at the period where you are so sulfur is impured what so we are also in the third period so the previous period was of course still PH2 so neon was the last noble gas before now this is where it becomes a bit interesting because you find that we're not just going to write the last orbital there will be some orbitals before that so moving from neon we've used up 10 electrons so as we move from Neon you find that we have to go through the S block so let's proclaim the fade period so this broke is 3s now since we are not ending there we have to fill it all up 3s2 if we end there then we are presenting magnesium now we are not representing magnetism so continue counting now there are no there is no D broke here so we're just leaving it blank and then we're now finding ourselves back in the P so the three will still apply to the P broke as well now I'm in are we counting so this is the fifth one the second fade and fourth so basically that's where it ends that is the noble gas electron configuration of sulfur using the noble gas electron configuration of course not very bad it's matching up it is matching up so what about if we try to make it a bit more interesting actually what about the one that is involved in the Deep Rock now uh what if we get to consider maybe something like let's consider vanadium let's consider something like Vanadium now so this is the way you're going to do it so we are in the fourth period fourth period That's where an idiom is now if you got the previous field which is the third one the last noble gases are gone so you write Argon now of course take note that argon has got taken up 18 electrons so we have to add to make it 23. okay so from Argon for me to get to vanity Festival pass through the the S broke which is in the fourth period so I have to fill it all up for S2 now if I add that first it means I've represented calcium now I've not represented calcium I need to get to Vanadium so this is exactly where the D Block is starting from now I mentioned earlier to say this is the first deep broke and the first deep broke according to what you had written was the third so that's why there is a bit of some lagging so if you're in the fourth period the D broke will be the third and so on and so forth so from there we understand that despite us being in the fourth period we are in the three deep walk so the first one is scandium so account one two so Vanadium is a third one so I'll put a three there wow interesting right so what is the noble gas electric configuration of an idiom using the short and rotation it's faster instead of you writing counting all the way from One S to over up to 3D to take a lot of time right it will okay so looking at this is very period so if we had gotten something like a Scenic which is like 33. would still use argon because it's the last one now the difference would be we know that for us to skip a d broke we have to put 10 electrons since we are not interested so if we end at 10 it implies we are representing zinc but we are not so continue moving so find ourselves back in the people because the p broke starts from the third pivot right so remember the p and the S matches up with a period Where You Are so still be in the 4p now counting from the first one one two three so it's for pe3 so this is the electron configuration using the number gas for asenic this is basically the way it gets to work I believe you now have an understanding on how you get to give a little configuration in a normal way using the orbitals and also using the shutdown notation also known as The Notebook as electron configuration thank you very much for watching this video in the next video we are going to talk about uh the exceptions to these configurations we've been giving copper chromium are the main exceptions to electronic configuration with some changes we don't basically just get to feel it though we've been filling in the others okay let's basically get to talk about the two exceptions to the main two exceptions to the electron configuration so basically the main two exceptions are chromium and copper in this case is uh there is a condition that a completely full or half filled up this sub level is more stable s this up levels so we'll see basically an excitement of an electron from the S going to the D orbital okay so this is our predictable we'll start by looking at the first one which is of course chromium right so I'll use the noble gas electron configuration if you are not acquainted with that you can watch a video using the tag above so that you know how to go about it so according to the noble gas electronic configuration periods are very necessary so that's the first period second third and the fourth so realize that for chromium we are in the fourth period right so you need to look at the previous period which is uh having argon as the last number gas so put Argon now from there we are now in the fourth period right before we get to to the chromium we know that the s the first group and the second group are the S broke whatever is here the transition elements are in the D broke and then these are the pin block we understand all that from that video if you watched it about the numbers electron configuration all right so before we basically get to get to Edinburgh we have to pass through the S block so the fourth period matches up with the S and the p so we have 4S so first to end since there are two groups in the S block we have to put two electrons so for S2 which represents calcium now when we are not interested in calcium so we have to proceed right so this is this this center part is the d block so the distance from Scandia so we have to count how many electrons we need for us to get to car chromium so one two three four so now we say there's a bit of lagging there's a lagging by one when you're dealing with a d block so since we're in the fourth period we expect that the D will be like by one which is 30. so expect to have four electrons in the Deep Rock now if you go back to the statement that we are dread this is the normal this is the expected electron configuration but it doesn't apply to chromia so it is better the chromium and the copper atoms are more stable when the D is either a field or fully filled than any other so therefore it would be better for the electron to move from the S orbital and get excited to the Deep Rock so that it becomes a field so with the S will lose one electron I need to go to the D so but it becomes redefined that was the exception that we were talking about and of course the same concept applies to Copper okay so what do we expect of copper so write that a bit down there so if you look at Copper if we start counting from where the D Block is starting from so we have one two three four five six seven eight nine so the expected electron configuration of copper since we're in the same period with chromium it will also use argon 4s2 3D 9. that's not text that's expected now there is also need of an excitement from the essay so I did it becomes fully filled that is going to be more stable and these are the main two exceptions so electron configuration hopefully you now understand thank you very much for watching all right so under atomic structure we have what we call quantum numbers so have you ever heard of the principle quantum number the angular momentum quantum number the magnetic quantum number the magnetic spin quantum number of course in association to the quantum numbers there is a principle we call poly Extrusion principle service principle tells us to say in a single atom not two electrons this is the key statement we will have an identical set of the same quantum numbers so the quantum numbers are in the brackets n l m l m s so these are the letters we're going to be working with under the study of quantum numbers so what we need to understand is there are no two electrons of the same atom but are going to have set of the same quantum numbers will be different we just have to be different even a single one has to be different they can't all be the same okay why is it so so a first quantum number that we saw is we saw n so we call that the principle quantum number so the principal random number is noted using the letter n so this represents the size and also the energy of the electron so under the study of atomic structure we did come make an argument to say there's an argument to say Atomic orbitals not necessary chemical videos of course let's talk about energy levels energy levels outer energy levels of energy levels that are further away from the nucleus they've got more energies compared to inans so in that if we are considering so the first energy level what that one or the second another third so we expect that the one with the said he has got more energy as compared to the two the first and the second so that's what we'll say in denotes the size and the energy so it's actually true n is equal to 3 is bigger in size as well as more energies compared to the first and the second in terms of the energy level so that's what the principal quantum number represents so it represents the energy level which of course represents the size and the energy number two angular momentum quantum number angular momentum so angular momentum quantum number is not reducing the letter L okay so this represents the shape the shape of the Orbiter so I believe we we already know the shapes of the orbiters so specifically we're going to be talking about the spdf orbitals spdf orbitals okay so this is going to be dependent on the principle quantum number understand how as we get to move and then the fades quantum number is the magnetic quantum number magnetic quantum number so denoted by ml okay it is ml because it's dependent on the angular momentum quantum numbers who understand as we move and finally the last one we have what you call the magnetic spin quantum number so of course I've not mentioned what the magnetic contact number basically gets to do not so magnetic quantum number denotes the orientation or the location so the orientation of the location and then magnetic spin quantum number denotes the direction so all this is going to make sense as we get to know so this is not a does the MS so I trust and believe that you understand basically the quantum numbers we have so let's try to understand the way we get to calculate them so I saved the first one is the principal quantum number denoted using small letter n so it's not the size and the energy okay so it will start with first of all n is equal to 1. so one thing that we do understand is that under the study of atomic structure we understand that each energy level occupies this is the number of electrons and since we know that the first accommodates a maximum of two the second the maximum of eight electrons at least we know this so a formula that we basically get to work with is 2 n squared so that is for the first energy level plugin A1 we have is n so 1 squared by 2 is just going to be a 2. for the second you do the same 2 squared to multiply by 2 by 8 so that matches up with the first two so for f8 you do the same substitute you basically get to have how many electrons so 3 squared is 9 times 2 8 10. so all this is supposed to be confirmed by the study of our quantum numbers so take note of this formula and then let's try to see what we're going to have so we've made an argument to say the principle quantum number is representing the energy level number one and that is true so from the principle on top number we are going to be magnificent momentum quantum number denoted by letter L so l is we say did not the shape of the orbital so we calculate L by moving from 0 to any minus 1. so whatever value of n you have subtract it by one and count from zero so in this case our n is just one so it's going to be one minus 1 which will just be zero so we'll say from zero to zero so zero to zero that's means we just have what is zero so in this case our L is just equal to zero so our L being equal to zero tells us to say since we said the orbitals we're dealing with are spdf so therefore in this case zero is not the first one that's the way it works so it's zero one two and three spdf so in this case we just have zero so we just have the S orbital now under the study of SPD four biters we did say that the S orbital accommodates the maximum of two electrons okay so for the ml which is the magnetic quantum number it is dependent on the L so it moves from the negative of L to its what to its positive so you count the way you count integers so if it's not making sense it will make more sense later so zero the negative zero the piece positive so zero doesn't have a positive and a negative so we just have a zero interesting and then finally the MS is the one that is unique and does not depend on anything okay so we just say it is just going to IB either a positive or a negative one so that implies it's either the electron is facing upwards or downwards so of course just a summary this denotes the energy level where you are this denotes the shape of the orbital in this case we'll say this s this denotes the orientation so the ml in other terms denotes the number of sub orbitals that we have so in this case it tells us we only have a single ad sub orbital and you say this sub orbital occupies the maximum is the maximum of two electrons so we only have two electrons in this case that's why the first energy level occupies only two electrons so the two electrons one is facing upward the other one is facing downwards but so we need to understand so let's try to verify the second part now let's say that n is equal to n is equal to 2. so we said our L which is our angular so in this case understand now that we are now talking about the second energy level we've proved using this formula to say it is how many electrons eight electrons so this has to verify that so from IO is equal to zero to two minus one since we are saying it is dependent on the principle quantum number so happens for quantum number in this case is a two so if you put two minus one so that's going to be that's what a one so the quantum numbers are going to have for your angular momentum will be zero and one because two minus 1 is just one so here we have two now now we say the L or the angular momentum quantum number denotes the shape so in this case we now have the S and the the B so our ml which is a magnetic quantum number gives us the orientation of the number of subatomic orbitals so each each l or each orbital of its own MLS so I'll start with L is equal to zero since we have L is equal to zero so just like from the first example we need to move from its negative it is positive so in this case Zero doesn't have a positive on the negative so it just be zero and then we also have l is equal to one from its negative to its positive sorry for me negative one all the way up to positive now I was saying these are denoting the number of subatomic orbitals so this tells us to say that the S orbital only has a single atomic orbital so it only applies a maximum of two electrons that is now for the p orbital it is telling us I just got three sub or technical videos negative 1 0 and d one so each with two electrons this explains why the p orbital has got how many electrons six electrons because it has got three subatomic orbitals okay verified by the quantum numbers so these basically these are this is actually what is basically true and then of course we know for MLS it is if you're talking about magnetic spin each mL of its own so it's all going to have a positive and a negative so for L is equal to zero where ml is equal to zero magnetic spin will be plus one and minus one and then you can talk about this individually as well for negative one it will also have a positive and a negative for zero positive or negative so meaning that in each orbital you'll be one electron facing upwards one facing dominance now we don't usually ask you about the magnetics in quanta because it will always give either a positive or A negative it is important for you to understand is the first three quantum numbers how exactly do you get to determine them so I'm showing you how you get to determine how many electrons each level occupies or accommodates using the the quantum numbers okay now the last example the last example to wrap it up let's say n is equal to skip the third one and I got the fourth one as the last one so we are in the fourth energy level so principal quantum number denotes the size on the energy and then the AO denotes now the the ship so if you remember there was a point where we are when giving an electron configuration we were using this I don't know if you've watched the video already you can check it out about our electron configuration so the four or the first one to have the F4 bitter so you saw that from our first we just add the SOB to from the second we've added the 2s and the 2p so we expect that for a fourth we should have all the way up to F let's try to see what's going to happen for the L so it would be from the 0 to n minus one so in this case our n is four four minus one is obviously going to be three so we have zero one two all the way up to three so all the orbitals are used up so say s p d and f okay so this basically verifies everything for the third if you try the third energy level it only end up to D to only be SPD that's the basic idea so this was not just guests this calculated using the quantum numbers are of course the ml is dependent on each value of L so we've already talked about L is equal to zero so for L is equal to zero moving from each negative 2 is positive it is only zero itself so we only have a single subatomic orbital under the s orbital for the p which is the one we have to move from its negative to its positive so L is equal to one we have to move from this negative is positive negative one zero and one for L is equal to 2 from its negative it's positive and then finally the last one L is equal to three so remember that this values that nothing they are shapes of the orbitals right so these are the number of subatomicalbiters you might you should expect so a I mean sub atomic computers do you have one just one which is a zero so it only has two electrons for this one that means about chemical because you have three which is six electrons as a p orbital since this is a remember this what is s p d and what and F okay take note of that from the angular momentum quantum number so a magnetic quantum number basically gets to verify everything we are talking about so yeah well five subatomical videos under the D so that's why it took past 10 electrons since it's subatomical video accommodates a maximum of two electrons and this basically has got seven so it gives us 14 electrons so this verifies why the spdf occupies the number of electrons that they do according to the quantum numbers so if you've given me a question where they give you the principle quantum number and ask you to determine the number of at subatomical videos it has in this case you have to add them on for the fourth energy level so we have one plus three giving you four four plus you know or another team those are the elections so we have two plus six eight plus ten eighteen eighteen plus fourteen is what 16. because each accommodates are many electrons to 16. that's how you basically get determine the number of subatomical videos okay so you're able to determine how many electrons I found known as the 10 energy level using the quantum numbers the able to determine the shape of orbitals that you can find on a specific energy level using the quantum numbers and of course let's try to confirm the poly Exclusion Principle why is it that not two electrons can have the same set of four quantum numbers so think of an electron that is contained in the fourth energy level contained in the in the s orbital or maybe it can even be more specific let me go to the P so from the p and then from zero so this was two electrons there you find that they are going to have n is equal to 4. they're all going to have L is equal to one they're all going to have m l is equal to zero as it's a subatomic orbital now for the last one it's either one is positive the one is negative so this is one thing that you can see one thing that you have to know about two electrons in the same subatomic orbital we've got the same principle quantum number same angular momentum quantum number same magnetic quantum number different magnetic spin quantum numbers that's why not it's not possible for all the four quantum numbers to be the same for two electrons that's what poly Extrusion principle says and we verified it using the quantum numbers okay so we go over SN began's attention principle so what is it all about so a basic idea is there is uncertainty in the act of measuring the position and the momentum of a particle so the simplified form that you can remember easy