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Introduction to Molecular Orbitals .txt | And in fact, when there are 0.7
angstromes, angstrom simply means one times ten to the negative 10 meters apart. When they're this distance apart, a bond will form, a covalent bond will form. And in fact, as you move the two H atoms closer and closer from a far distance apart, energy begins to decrease until we reach this point, until we reach 0.7
angstromes away. So if we graph energy versus our distance between them, we will see that a distance far apart, somewhere right here, we're going to have some energy. And as we begin moving them closer and closer, our energy will begin to decrease until we reach this point. And at this point, we have the minimum amount of energy. |
Introduction to Molecular Orbitals .txt | So if we graph energy versus our distance between them, we will see that a distance far apart, somewhere right here, we're going to have some energy. And as we begin moving them closer and closer, our energy will begin to decrease until we reach this point. And at this point, we have the minimum amount of energy. In other words, nature likes to minimize energy. The more destabilizing it is, the more energy we have. The less energy we have, the more stabilizing our compound is. |
Introduction to Molecular Orbitals .txt | In other words, nature likes to minimize energy. The more destabilizing it is, the more energy we have. The less energy we have, the more stabilizing our compound is. So, in other words, the beginning condition, our initial atoms are at a higher energy than our final molecule. Now, what happens when I continue pushing them closer and closer? Well, as that begins pushing them closer and closer and closer, the repulsion forces begin to increase dramatically. |
Introduction to Molecular Orbitals .txt | So, in other words, the beginning condition, our initial atoms are at a higher energy than our final molecule. Now, what happens when I continue pushing them closer and closer? Well, as that begins pushing them closer and closer and closer, the repulsion forces begin to increase dramatically. And that's exactly why we see that as we go past 0.7 atroms, our energy begins to increase. So as you bring atoms closer and closer, repulsion of the positively charged nuclei causes a sharp increase in energy, as we see here. So as they're moving closer past the distance, the electrons, as well, as protons begin to repel one another, and the energy dramatically increases once again. |
Introduction to Molecular Orbitals .txt | And that's exactly why we see that as we go past 0.7 atroms, our energy begins to increase. So as you bring atoms closer and closer, repulsion of the positively charged nuclei causes a sharp increase in energy, as we see here. So as they're moving closer past the distance, the electrons, as well, as protons begin to repel one another, and the energy dramatically increases once again. To recap, nature likes to form stabilizing structures. Nature will not form a structure that is higher in energy. In other words, if this was higher in energy than this, this molecule would not form. |
Introduction to Molecular Orbitals .txt | To recap, nature likes to form stabilizing structures. Nature will not form a structure that is higher in energy. In other words, if this was higher in energy than this, this molecule would not form. The reason this form spontaneously is because our energy of initial molecules or atoms is lower than the final. So now, let's examine atomic orbitals. So, what is the atomic orbital that our electron is in? |
Introduction to Molecular Orbitals .txt | The reason this form spontaneously is because our energy of initial molecules or atoms is lower than the final. So now, let's examine atomic orbitals. So, what is the atomic orbital that our electron is in? Well, it's the one S orbital. So let's say we have this atom. Let's call it ha subscript A. |
Introduction to Molecular Orbitals .txt | Well, it's the one S orbital. So let's say we have this atom. Let's call it ha subscript A. And let's call this guy H subscript B. So this here, this PSI, Greek letter PSI, simply represents the orbital or wave function. So let's say PSI subscript haply means that this is the one S orbital of our ha atom. |
Introduction to Molecular Orbitals .txt | And let's call this guy H subscript B. So this here, this PSI, Greek letter PSI, simply represents the orbital or wave function. So let's say PSI subscript haply means that this is the one S orbital of our ha atom. And this is the one s orbital of our HB atom. So when these orbitals atomic orbitals are very far apart, nothing really happens. But as I move them closer and closer, eventually, when I get to this point, these atomic orbitals will overlap, and they will create something known as the molecular orbital or molecular bonding orbital. |
Introduction to Molecular Orbitals .txt | And this is the one s orbital of our HB atom. So when these orbitals atomic orbitals are very far apart, nothing really happens. But as I move them closer and closer, eventually, when I get to this point, these atomic orbitals will overlap, and they will create something known as the molecular orbital or molecular bonding orbital. Now, this guy is represented by PSI phi. So phi bonding is our molecular orbital. So when we see this symbol, we usually think atomic orbitals. |
Introduction to Molecular Orbitals .txt | Now, this guy is represented by PSI phi. So phi bonding is our molecular orbital. So when we see this symbol, we usually think atomic orbitals. And this is five. When we see this symbol five, we think about molecular orbitals. So, once again, atomic orbitals will combine two form molecular orbitals, or also known as covalent bonds. |
Introduction to Molecular Orbitals .txt | And this is five. When we see this symbol five, we think about molecular orbitals. So, once again, atomic orbitals will combine two form molecular orbitals, or also known as covalent bonds. Now, from quantum mechanics, we know that whatever number of atomic orbitals that combine, they will form the same amount of molecular orbitals. In other words, there's a conservation number that we have to take into consideration. So, because two atomic orbitals combined, we should form two molecular orbitals. |
Acid Strength.txt | So before we talk about acid and basis, we must define what acid and bases are. Well, if you want to learn more about the various types of definitions that exist between acid and bases, check out the link below. In this lecture we're going to focus on the bronzed lottery acid based concept. So according to that definition, acids are defined by their ability to donate an H plus ion, while bases are defined by their ability to accept an H plus ion. So what makes a compound X a better acid than compound Y? Well, stronger acids are better at donating than H plus ion than weaker acids are. |
Acid Strength.txt | So according to that definition, acids are defined by their ability to donate an H plus ion, while bases are defined by their ability to accept an H plus ion. So what makes a compound X a better acid than compound Y? Well, stronger acids are better at donating than H plus ion than weaker acids are. And stronger bases are better at accepting that H plus ion than weaker bases. That means the reason that compound X is a better asset than compound Y well, is because compound X releases that H ion with greater ease compared to compound Y. Now, three things make up a good asset bond strength, polarity of bond, and stability of conjugate base. |
Acid Strength.txt | And stronger bases are better at accepting that H plus ion than weaker bases. That means the reason that compound X is a better asset than compound Y well, is because compound X releases that H ion with greater ease compared to compound Y. Now, three things make up a good asset bond strength, polarity of bond, and stability of conjugate base. So how strong is the bond connecting the H ion and the atom in the compound? Well, suppose you're holding somebody's hand and you're holding their hand tightly with a good grip. Well, then the other person will not be able to let go of their hand that easily. |
Acid Strength.txt | So how strong is the bond connecting the H ion and the atom in the compound? Well, suppose you're holding somebody's hand and you're holding their hand tightly with a good grip. Well, then the other person will not be able to let go of their hand that easily. However, if your grip is weak and you're not holding it tightly, then that person will be able to let go of their hand the same way that weak bonds will release the H plus ion with greater ease. So whenever you have a base that comes around, that base will be able to take away that H plus ion if the bond is weak. So weaker bonds equals better acids. |
Acid Strength.txt | However, if your grip is weak and you're not holding it tightly, then that person will be able to let go of their hand the same way that weak bonds will release the H plus ion with greater ease. So whenever you have a base that comes around, that base will be able to take away that H plus ion if the bond is weak. So weaker bonds equals better acids. So let's look at the polarity of our bond. So how polar is our bond? Let's examine HCH bond in a methane and an HCL bond in a hydrochloric acid or HCL. |
Acid Strength.txt | So let's look at the polarity of our bond. So how polar is our bond? Let's examine HCH bond in a methane and an HCL bond in a hydrochloric acid or HCL. So the strength of these bonds is relatively the same. So if we strictly look at part C, the bond strength, we will determine that our acid strength is the same. But that's not the case. |
Acid Strength.txt | So the strength of these bonds is relatively the same. So if we strictly look at part C, the bond strength, we will determine that our acid strength is the same. But that's not the case. This is a much better asset than our methane molecule. So why is that? Well, we have to look at the polarity. |
Acid Strength.txt | This is a much better asset than our methane molecule. So why is that? Well, we have to look at the polarity. Remember, polarity comes from electronegativity. And the greater the difference in electronegativity, the more polar our bond is. So let's look at this guy. |
Acid Strength.txt | Remember, polarity comes from electronegativity. And the greater the difference in electronegativity, the more polar our bond is. So let's look at this guy. The difference between electronegativity between the C atom and the H atom is smaller than the difference between a CL atom and the H atom. And that's because the CL atom is much more electronic negative. That means it's going to pull the electrons toward itself. |
Acid Strength.txt | The difference between electronegativity between the C atom and the H atom is smaller than the difference between a CL atom and the H atom. And that's because the CL atom is much more electronic negative. That means it's going to pull the electrons toward itself. So the density will not be equal, whereas here it will be equal, or pretty much equal. Therefore, this section of the bond will be weak. And so when a base comes around, it will be able to pull away this H atom with greater ease. |
Acid Strength.txt | So the density will not be equal, whereas here it will be equal, or pretty much equal. Therefore, this section of the bond will be weak. And so when a base comes around, it will be able to pull away this H atom with greater ease. Therefore, the more polar our bond, the more likely that it will break and release that H plus ion. Finally, let's look at the stability of conjugate bases. Now, if you forgot what a conjugate acid in base is, check out the link below. |
Acid Strength.txt | Therefore, the more polar our bond, the more likely that it will break and release that H plus ion. Finally, let's look at the stability of conjugate bases. Now, if you forgot what a conjugate acid in base is, check out the link below. Now, we're going to explore the difference between chloric acid and hypochlorous acid. So if we look at the polarity and the bond strength, we see that this ho bond and this ho bond are identical. And that means, according to polarity and bond strength, these assets should have the same strain. |
Acid Strength.txt | Now, we're going to explore the difference between chloric acid and hypochlorous acid. So if we look at the polarity and the bond strength, we see that this ho bond and this ho bond are identical. And that means, according to polarity and bond strength, these assets should have the same strain. But experimentally, we know that chlorot acid is a better asset than the Hypochlorous acid. So let's examine why this has to do with conjugate basis. Let's look at the conjugate base of Hypochlorous acid. |
Acid Strength.txt | But experimentally, we know that chlorot acid is a better asset than the Hypochlorous acid. So let's examine why this has to do with conjugate basis. Let's look at the conjugate base of Hypochlorous acid. While when this H associates, it creates a negative charge on the O atom, creating this guy here. Now, this guy can be resonant stabilized by the formation of a double bond, and this creates a negative charge on the seal atom. So we have two resonance stabilized states. |
Acid Strength.txt | While when this H associates, it creates a negative charge on the O atom, creating this guy here. Now, this guy can be resonant stabilized by the formation of a double bond, and this creates a negative charge on the seal atom. So we have two resonance stabilized states. Now, let's examine the conjugate base of our chloric acid. Well, this guy is resonant stabilized by three states, in fact, four states. I'll show you the last one in a bit. |
Acid Strength.txt | Now, let's examine the conjugate base of our chloric acid. Well, this guy is resonant stabilized by three states, in fact, four states. I'll show you the last one in a bit. So this negative atom can be distributed to this oxygen and then this oxygen. And that happens when this guy forms a double bond, displacing this bond, forming a negative bond here. And then this lone pair forms a double bond with this bond, displacing this lone pair, creating a negative charge here. |
Acid Strength.txt | So this negative atom can be distributed to this oxygen and then this oxygen. And that happens when this guy forms a double bond, displacing this bond, forming a negative bond here. And then this lone pair forms a double bond with this bond, displacing this lone pair, creating a negative charge here. In fact, a fourth resonance stabilized state exists in which three double bonds exist, and the CL atom has a negative charge. So we see that resonance stabilization is good. Whenever we have more resonance stabilization, that means we have a more stable conjugate base. |
Acid Strength.txt | In fact, a fourth resonance stabilized state exists in which three double bonds exist, and the CL atom has a negative charge. So we see that resonance stabilization is good. Whenever we have more resonance stabilization, that means we have a more stable conjugate base. So this guy will exist, and it will be more likely that it will exist than this guy. And therefore, chloride acid will be more likely to go this way to lose and dissociate and to form this state than this guy. This guy will be less likely to dissociate because it's only stabilized by two resonance stabilized states, or its conjugate base is only stabilized by two states versus four states in this case. |
Acid Strength.txt | So this guy will exist, and it will be more likely that it will exist than this guy. And therefore, chloride acid will be more likely to go this way to lose and dissociate and to form this state than this guy. This guy will be less likely to dissociate because it's only stabilized by two resonance stabilized states, or its conjugate base is only stabilized by two states versus four states in this case. So, once again, the more stable our conjugate base is, the stronger our asset. That also means as acid strain decreases, say, from going this guy to going to this guy, the strength of our conjugate base increases. In other words, this guy will be more likely to accept an atom and go to this guy than this guy because this guy exists by itself in a more stable state. |
Cell Voltage Equation .txt | So let's begin by first writing out the two half reactions of this reduction reaction. So let's see which guy is oxidized and which guy is reduced. Well, our iron atom goes from a neutral charge to a plus two charge, while our cavmium atom goes from a plus two charge to a neutral charge. That means this atom loses two electrons and this atom gains those same two electrons. So this is our oxidized atom and our reduced atom or our reducing agent and oxidizing agent. So let's go to step one and let's see our two half reactions. |
Cell Voltage Equation .txt | That means this atom loses two electrons and this atom gains those same two electrons. So this is our oxidized atom and our reduced atom or our reducing agent and oxidizing agent. So let's go to step one and let's see our two half reactions. So our oxidation half reaction is the following. Our solid iron becomes a positively charged molecule plus two electrons because it releases those two electrons while our cadmium aqueous atom gains those two electrons forming our cadmium solid. So this is our reduction reaction and oxidation reaction. |
Cell Voltage Equation .txt | So our oxidation half reaction is the following. Our solid iron becomes a positively charged molecule plus two electrons because it releases those two electrons while our cadmium aqueous atom gains those two electrons forming our cadmium solid. So this is our reduction reaction and oxidation reaction. So let's look at the cell diagram for this electrochemical cell. So remember, these two vertical lines represent the sole bridge and these guys simply represent separations of phases. So this and this are in different phases and these guys are in different phases also. |
Cell Voltage Equation .txt | So let's look at the cell diagram for this electrochemical cell. So remember, these two vertical lines represent the sole bridge and these guys simply represent separations of phases. So this and this are in different phases and these guys are in different phases also. So this is our anode and this is our cathode. So what happens is two electrons leave this atom forming our aqueous iron atom and these two electrons travel via the conductor to this guy reacting with this positively charged atom forming our solid cadmium. So let's go to step two. |
Cell Voltage Equation .txt | So this is our anode and this is our cathode. So what happens is two electrons leave this atom forming our aqueous iron atom and these two electrons travel via the conductor to this guy reacting with this positively charged atom forming our solid cadmium. So let's go to step two. Now, in step two and three, what we want to do or do is find a cell voltage of our electrochemical cell and then use the cell voltage to find our equilibrium constant KC. So let's go to step two. Now, this is our formula that we want to use to find the cell voltage where this is the cell voltage of the reduction reaction and the cell voltage of the oxidation reaction. |
Cell Voltage Equation .txt | Now, in step two and three, what we want to do or do is find a cell voltage of our electrochemical cell and then use the cell voltage to find our equilibrium constant KC. So let's go to step two. Now, this is our formula that we want to use to find the cell voltage where this is the cell voltage of the reduction reaction and the cell voltage of the oxidation reaction. Now, we basically look these guys up on our table for reduction half reactions on the statement conditions and we find that our reduction cell voltage is zero point 43 negative, while our oxidation half reaction is negative zero point 44. Well, actually our reduction going this way because only reduction half reactions are listed. So we have to look at the guy going this way. |
Cell Voltage Equation .txt | Now, we basically look these guys up on our table for reduction half reactions on the statement conditions and we find that our reduction cell voltage is zero point 43 negative, while our oxidation half reaction is negative zero point 44. Well, actually our reduction going this way because only reduction half reactions are listed. So we have to look at the guy going this way. So that is negative zero point 44. Now, I put this negative here in here because we want to convert this to an oxidation because in this anode oxidation that reduction occurs and that's why we have the negative sign here. So what we get is these negatives become a positive and we basically add this guy to this guy and we get zero point 37 volts. |
Cell Voltage Equation .txt | So that is negative zero point 44. Now, I put this negative here in here because we want to convert this to an oxidation because in this anode oxidation that reduction occurs and that's why we have the negative sign here. So what we get is these negatives become a positive and we basically add this guy to this guy and we get zero point 37 volts. This is our cell voltage of our electrochemical cell. Now, in the previous lecture we learned that there's a relationship between our cell voltage and our equilibrium constant, namely this equation here. Now, we also saw in that same lecture that we can convert this formula at 25 degrees Celsius to the following formula. |
Cell Voltage Equation .txt | This is our cell voltage of our electrochemical cell. Now, in the previous lecture we learned that there's a relationship between our cell voltage and our equilibrium constant, namely this equation here. Now, we also saw in that same lecture that we can convert this formula at 25 degrees Celsius to the following formula. Log k equals number of moles times our cell voltage divided by this number here. Zero point 52. Now, this number comes from the fact that both r and F are constants. |
Cell Voltage Equation .txt | Log k equals number of moles times our cell voltage divided by this number here. Zero point 52. Now, this number comes from the fact that both r and F are constants. And at 25 degrees Celsius, t is also constant. Now t is in Kelvin. And we also basically converted our natural log to log of base ten. |
Cell Voltage Equation .txt | And at 25 degrees Celsius, t is also constant. Now t is in Kelvin. And we also basically converted our natural log to log of base ten. Now, let's plug our guides in. So our E is from here, and n, we look at this equation. We see that N represents two moles of electrons. |
Cell Voltage Equation .txt | Now, let's plug our guides in. So our E is from here, and n, we look at this equation. We see that N represents two moles of electrons. So n is two. That's what we get. Two times zero point 37 results from this guy divided by zero point 52, and we get 1.25 equals log k.
Now, we change this entire thing to exponents, and we get ten to the 1.5. |
Cell Voltage Equation .txt | So n is two. That's what we get. Two times zero point 37 results from this guy divided by zero point 52, and we get 1.25 equals log k.
Now, we change this entire thing to exponents, and we get ten to the 1.5. You plug that into the calculator, and it's approximately 17.8. So our K is 17.8. And what does that mean? |
Cell Voltage Equation .txt | You plug that into the calculator, and it's approximately 17.8. So our K is 17.8. And what does that mean? Well, remember we said if our K is above one, that means our reaction is product favorite. It's spontaneous. So this guy, the equilibrium lies on the right. |
Cell Voltage Equation .txt | Well, remember we said if our K is above one, that means our reaction is product favorite. It's spontaneous. So this guy, the equilibrium lies on the right. That means almost all of these guys are converted to our products. And this is the same thing as our e. Remember, our E says what our E gives us a positive value for cell voltage and what the a positive value for cell voltage mean? Remember, a positive value for cell voltage means our reaction is product favored, and a negative value means it's reacting favored. |
Polar and Nonpolar Covalent Bonds .txt | So here we have the nonpolar covalent bonds, and here we have the polar covalent bond. Now, notice right off the bat the similarity. Both guys, both bonds are covalent bonds. And what, what that simply means is that there is a sharing of electrons. In other words, one atom donates an electron and a second atom also donates an electron. The difference lies is a polarity and we'll see what that means in just a second. |
Polar and Nonpolar Covalent Bonds .txt | And what, what that simply means is that there is a sharing of electrons. In other words, one atom donates an electron and a second atom also donates an electron. The difference lies is a polarity and we'll see what that means in just a second. So let's begin with the non polar covalent bond. So let's suppose we have two atoms. So two atoms that are exactly the same mean they have the same amount of protons in the nucleus and the same amount of electrons. |
Polar and Nonpolar Covalent Bonds .txt | So let's begin with the non polar covalent bond. So let's suppose we have two atoms. So two atoms that are exactly the same mean they have the same amount of protons in the nucleus and the same amount of electrons. So here we have our picture where we have our nucleus one with some amount of electrons and nucleus two with the same amount with the same number of electrons. And each nucleus or each atom donates an electron. So one coming from this atom and the second coming from this atom. |
Polar and Nonpolar Covalent Bonds .txt | So here we have our picture where we have our nucleus one with some amount of electrons and nucleus two with the same amount with the same number of electrons. And each nucleus or each atom donates an electron. So one coming from this atom and the second coming from this atom. So let's look at Coulomb's law for a second. Coulomb's law gives us the force felt by two charges some distance apart. What it states is the following. |
Polar and Nonpolar Covalent Bonds .txt | So let's look at Coulomb's law for a second. Coulomb's law gives us the force felt by two charges some distance apart. What it states is the following. If we have two charges, q one and Q two, if we multiply them together and multiplied by the constant k and divided by the distance between their center of charges squared, we get the force that each charge feels due to the other charge. Remember, plus charges repel and plus and minus attract. So notice what we have here. |
Polar and Nonpolar Covalent Bonds .txt | If we have two charges, q one and Q two, if we multiply them together and multiplied by the constant k and divided by the distance between their center of charges squared, we get the force that each charge feels due to the other charge. Remember, plus charges repel and plus and minus attract. So notice what we have here. The charge in this nucleus is the same as the charge in this nucleus because we have the same amount of protons in those nuclei. And we both have one electrons, one electron here and one electron here. And they also have the same amount of charge. |
Polar and Nonpolar Covalent Bonds .txt | The charge in this nucleus is the same as the charge in this nucleus because we have the same amount of protons in those nuclei. And we both have one electrons, one electron here and one electron here. And they also have the same amount of charge. So that means that this nuclei will exert a force on this electron and this force will be equal to the force that this nuclei nucleus exerts on this electron. So this electron will pull this or this proton will pull this electron with the same amount of force that this proton will pull on this electron. So there will be an equal distribution of charge. |
Polar and Nonpolar Covalent Bonds .txt | So that means that this nuclei will exert a force on this electron and this force will be equal to the force that this nuclei nucleus exerts on this electron. So this electron will pull this or this proton will pull this electron with the same amount of force that this proton will pull on this electron. So there will be an equal distribution of charge. These electrons will be found equidistant between these two nuclei. Distance will be the same exact. And this only occurs when we have the same amount of protons found in the nucleus. |
Polar and Nonpolar Covalent Bonds .txt | These electrons will be found equidistant between these two nuclei. Distance will be the same exact. And this only occurs when we have the same amount of protons found in the nucleus. So for example, if we have an H and an H, both nuclei have one protons each. If we have an F and an F, both nuclei have nine protons each and so on. Basically, when we have two of the same atoms, we're going to have a non polar covalent bond as we have here and as we have here. |
Polar and Nonpolar Covalent Bonds .txt | So for example, if we have an H and an H, both nuclei have one protons each. If we have an F and an F, both nuclei have nine protons each and so on. Basically, when we have two of the same atoms, we're going to have a non polar covalent bond as we have here and as we have here. Now, notice we have a double bond here. But it doesn't change the fact that this is a nonpolar covalent bond because we have an oxygen with some amount of protons and a second oxygen with the same amount of protons. Now, another way to look at it is via electronegativity. |
Polar and Nonpolar Covalent Bonds .txt | Now, notice we have a double bond here. But it doesn't change the fact that this is a nonpolar covalent bond because we have an oxygen with some amount of protons and a second oxygen with the same amount of protons. Now, another way to look at it is via electronegativity. Now, both atoms have the same amount of electronegativity and that simply means they will attract electrons with the same affinity. And that basically means that our electrons will be found smack in the middle. They'll be equidistant between our two atoms. |
Polar and Nonpolar Covalent Bonds .txt | Now, both atoms have the same amount of electronegativity and that simply means they will attract electrons with the same affinity. And that basically means that our electrons will be found smack in the middle. They'll be equidistant between our two atoms. And so we're going to have symmetry. In other words, if we take a line and cross it this way, this section will be symmetrical to this section. And that means we're going to have a non polar covalent bond. |
Polar and Nonpolar Covalent Bonds .txt | And so we're going to have symmetry. In other words, if we take a line and cross it this way, this section will be symmetrical to this section. And that means we're going to have a non polar covalent bond. Now let's look at polar covalent bonds. Polar covalent bond simply means there will be an unequal distribution of charge. And let's see why. |
Polar and Nonpolar Covalent Bonds .txt | Now let's look at polar covalent bonds. Polar covalent bond simply means there will be an unequal distribution of charge. And let's see why. Well, suppose we have an atom and a second atom that have different number of protons in their nuclei. Suppose we have a larger atom with a larger number of protons than this atom. And what that basically means, because of coulomb law, because the charge will be greater for this nucleus than for this nucleus, the force that these electrons feel due to this nucleus will be larger than due to this nucleus. |
Polar and Nonpolar Covalent Bonds .txt | Well, suppose we have an atom and a second atom that have different number of protons in their nuclei. Suppose we have a larger atom with a larger number of protons than this atom. And what that basically means, because of coulomb law, because the charge will be greater for this nucleus than for this nucleus, the force that these electrons feel due to this nucleus will be larger than due to this nucleus. And so there will be an unequal sharing or an unequal distribution of electrons. So there will be an unequal distribution of charge between these two atoms. And that means we're going to have a polar covalent bond. |
Polar and Nonpolar Covalent Bonds .txt | And so there will be an unequal sharing or an unequal distribution of electrons. So there will be an unequal distribution of charge between these two atoms. And that means we're going to have a polar covalent bond. Now, another way we're presenting this is by the following depiction. So because our electrons will be closer to the larger atom, we're going to develop a partial, not a full, but a partial negative charge. This simply means partial negative. |
Polar and Nonpolar Covalent Bonds .txt | Now, another way we're presenting this is by the following depiction. So because our electrons will be closer to the larger atom, we're going to develop a partial, not a full, but a partial negative charge. This simply means partial negative. Now, there will be a partial positive charge because electrons will be shifted this way. There will be a partial positive charge on this smaller atom. Now, examples include HF, hohc and many, many more examples. |
Polar and Nonpolar Covalent Bonds .txt | Now, there will be a partial positive charge because electrons will be shifted this way. There will be a partial positive charge on this smaller atom. Now, examples include HF, hohc and many, many more examples. Basically, whenever you have two different atoms, such as here HF, we're going to have an equal distribution of charge. Electrons are going to be closer to the larger atom because this f, for example, has nine protons, while this h has only one proton. So our nucleus will pull these electrons stronger than the h. So our electrons will be closer this way. |
Polar and Nonpolar Covalent Bonds .txt | Basically, whenever you have two different atoms, such as here HF, we're going to have an equal distribution of charge. Electrons are going to be closer to the larger atom because this f, for example, has nine protons, while this h has only one proton. So our nucleus will pull these electrons stronger than the h. So our electrons will be closer this way. Now, another way of representing this unequal distribution is by using this arrow. So we draw an arrow towards where our electrons are being pulled and our electrons are being pulled towards the larger nucleus. So towards the f.
And we draw kind of a plus sign on the end where there's a partial positive charge. |
Polar and Nonpolar Covalent Bonds .txt | Now, another way of representing this unequal distribution is by using this arrow. So we draw an arrow towards where our electrons are being pulled and our electrons are being pulled towards the larger nucleus. So towards the f.
And we draw kind of a plus sign on the end where there's a partial positive charge. So the same thing goes for h and o, we're going to have an arrow this way and we're going to have an arrow this way. Now, another way of looking at this is via electronegativity. The atom that has a larger electronegativity, it will pull or attract electrons more strongly. |
Polar and Nonpolar Covalent Bonds .txt | So the same thing goes for h and o, we're going to have an arrow this way and we're going to have an arrow this way. Now, another way of looking at this is via electronegativity. The atom that has a larger electronegativity, it will pull or attract electrons more strongly. That means we're going to have because this one is more electronegative than this atom. And this one is more electronegative than this and this is more electronegative than this. We're going to have our error pointing in this direction and we're going to have a polar covalent bond. |
Cis-Trans Z-e Isomer Stability .txt | So for any given alkene, may different types of isomers can exist. In this lecture we're going to compare the sits or the Z isomers with the trans or the E isomers. And we're going to discuss which ones are more stable. So let's suppose we're working with three hexane. Now three hexane has two types of isomers. It has the trans three hexen isomer or the e three hexenisomer. |
Cis-Trans Z-e Isomer Stability .txt | So let's suppose we're working with three hexane. Now three hexane has two types of isomers. It has the trans three hexen isomer or the e three hexenisomer. And there's also the S three hexenisomer or the Z three hexane isomer. Now, trans simply means the smaller H groups are on opposite sides of the double bond, while the E means that the two higher priority groups are in opposite sides of our double bond. Likewise, sin simply means that the two H groups are on the same side of the double bond, while the Z means that the two priority, the higher priority groups are the same side of the double bond. |
Cis-Trans Z-e Isomer Stability .txt | And there's also the S three hexenisomer or the Z three hexane isomer. Now, trans simply means the smaller H groups are on opposite sides of the double bond, while the E means that the two higher priority groups are in opposite sides of our double bond. Likewise, sin simply means that the two H groups are on the same side of the double bond, while the Z means that the two priority, the higher priority groups are the same side of the double bond. So we have trans and we have the CIS three hexane. So let's examine our three dimensional model of this three hexane. So here we have our CIS three hexane. |
Cis-Trans Z-e Isomer Stability .txt | So we have trans and we have the CIS three hexane. So let's examine our three dimensional model of this three hexane. So here we have our CIS three hexane. So here's our double bond and here our single bonds. So we have the methyl group, the methyl group and our two HS here. Now, one important detail that you must remember about double bonds versus single bonds. |
Cis-Trans Z-e Isomer Stability .txt | So here's our double bond and here our single bonds. So we have the methyl group, the methyl group and our two HS here. Now, one important detail that you must remember about double bonds versus single bonds. Double bonds do not rotate their rigid while single bonds, single covalent bonds are able to rotate. So this bond here will rotate and this bond here will also rotate. So let's suppose that this bond rotates and this bond also rotates. |
Cis-Trans Z-e Isomer Stability .txt | Double bonds do not rotate their rigid while single bonds, single covalent bonds are able to rotate. So this bond here will rotate and this bond here will also rotate. So let's suppose that this bond rotates and this bond also rotates. What will happen then? Well, if these two bonds rotate, look at what happens when they rotate. They will bump and this bumping will cause steric hinderance. |
Cis-Trans Z-e Isomer Stability .txt | What will happen then? Well, if these two bonds rotate, look at what happens when they rotate. They will bump and this bumping will cause steric hinderance. This will interfere and destabilize this CIS three hexane. In other words, there is this bumping effect when these two single bonds rotate. And this means or this creates a high energy destabilizing interaction in the CIS compound. |
Cis-Trans Z-e Isomer Stability .txt | This will interfere and destabilize this CIS three hexane. In other words, there is this bumping effect when these two single bonds rotate. And this means or this creates a high energy destabilizing interaction in the CIS compound. What about our trans compound? Let's suppose we move this ethyl group into or onto the bottom and now we have our transexane. So now no matter how much they rotate, there's no interaction between these destabilizing ethyl groups between these large ethyl groups. |
Cis-Trans Z-e Isomer Stability .txt | What about our trans compound? Let's suppose we move this ethyl group into or onto the bottom and now we have our transexane. So now no matter how much they rotate, there's no interaction between these destabilizing ethyl groups between these large ethyl groups. And that means the trans isomer is the more stable isomer because it does not have the destabilizing interaction between the two ethyl groups like in the CIS compound. Therefore, it has a lower or more negative enthalpy of formation. There is a difference of about one kilogal per mole of energy between this guy and this compound. |
Using a Barometer .txt | Now, you take the cup, you fill it up with mercury. You take the tube, you fill that up to the rib of mercury. You take the tube, flip it upside down, and place it into the cup. Now, once you place it to the cup, a vacuum is created in this section. And that's because the force of gravity pulls down on the liquid. But it will pull down to a certain extent. |
Using a Barometer .txt | Now, once you place it to the cup, a vacuum is created in this section. And that's because the force of gravity pulls down on the liquid. But it will pull down to a certain extent. And that's because the air molecules found on the outside, such as oxygen molecules, carbon dioxide molecules, nitrogen molecules, exert a certain force on these two sections here on this liquid. And when the force of these molecules equals the force of the gravity on the liquid, when these two forces equal, it will stop pulling down, and it will level off at some height H. So then you can calculate that height, H, from this point to this point. And you can use this formula to find the pressure of the atmosphere where pressure is equal to density of liquid times gravitational constant times height H.
So let's see what happens when the atmosphere pressure increases. |
Using a Barometer .txt | And that's because the air molecules found on the outside, such as oxygen molecules, carbon dioxide molecules, nitrogen molecules, exert a certain force on these two sections here on this liquid. And when the force of these molecules equals the force of the gravity on the liquid, when these two forces equal, it will stop pulling down, and it will level off at some height H. So then you can calculate that height, H, from this point to this point. And you can use this formula to find the pressure of the atmosphere where pressure is equal to density of liquid times gravitational constant times height H.
So let's see what happens when the atmosphere pressure increases. Suppose you decrease the altitude where you are measuring the pressure, so the pressure increases. If the pressure increases, then the force will increase. That's pushing down this liquid. |
Using a Barometer .txt | Suppose you decrease the altitude where you are measuring the pressure, so the pressure increases. If the pressure increases, then the force will increase. That's pushing down this liquid. It will push the liquid down lower and will raise this higher. So h will increase. And according to the formula, we see just that. |
Using a Barometer .txt | It will push the liquid down lower and will raise this higher. So h will increase. And according to the formula, we see just that. If the pressure has increased while these two guys are held constant, h will increase. The same is true for a lower pressure. Suppose we go higher up to some mountain top. |
Using a Barometer .txt | If the pressure has increased while these two guys are held constant, h will increase. The same is true for a lower pressure. Suppose we go higher up to some mountain top. At this mountaintop, the pressure is lower. So H will be lower as well, because these two guys are constant. And that's because if the pressure is lower, the force of gravity will be higher. |
Using a Barometer .txt | At this mountaintop, the pressure is lower. So H will be lower as well, because these two guys are constant. And that's because if the pressure is lower, the force of gravity will be higher. And so it will push this level up, and it will lower this level. Okay? So the height, the total height, will be lower. |
Using a Barometer .txt | And so it will push this level up, and it will lower this level. Okay? So the height, the total height, will be lower. Now, last thing I want to talk about is this little vacuum here. Now, remember, this liquid we chose, mercury, will evaporate some of its molecules. So technically, this isn't a vacuum. |
Using a Barometer .txt | Now, last thing I want to talk about is this little vacuum here. Now, remember, this liquid we chose, mercury, will evaporate some of its molecules. So technically, this isn't a vacuum. And there are some vapor molecules flowing around or flying around in this area in the space here. Now, what happens if we increase the vapor pressure here? If we increase the vapor pressure, the pressure due to the molecules in the air will push on this section here. |
Using a Barometer .txt | And there are some vapor molecules flowing around or flying around in this area in the space here. Now, what happens if we increase the vapor pressure here? If we increase the vapor pressure, the pressure due to the molecules in the air will push on this section here. It will decrease this level and decrease the height. So there will be some discrepancy in the atmospheric pressure if there are molecules found within this section. So the more volatile the liquid that's used in this section, the higher the bigger pressure is. |
Using a Barometer .txt | It will decrease this level and decrease the height. So there will be some discrepancy in the atmospheric pressure if there are molecules found within this section. So the more volatile the liquid that's used in this section, the higher the bigger pressure is. And that means the larger the difference from here to here, the lower this section will be. Now, the same way that you could measure the temperature of the atmosphere using a thermometer, you can also measure atmospheric pressure using a barometer. A barometer can be semblasing three things a long cylindrical tube open at one end and then select usually mercury and a cup. |
Using a Barometer .txt | And that means the larger the difference from here to here, the lower this section will be. Now, the same way that you could measure the temperature of the atmosphere using a thermometer, you can also measure atmospheric pressure using a barometer. A barometer can be semblasing three things a long cylindrical tube open at one end and then select usually mercury and a cup. Now, you take the cup, you fill it up with mercury. You take the tube, you fill that up to the rib of mercury. You take the tube, flip it upside down, and place it into the cup. |
Using a Barometer .txt | Now, you take the cup, you fill it up with mercury. You take the tube, you fill that up to the rib of mercury. You take the tube, flip it upside down, and place it into the cup. Now, once you place it to the cup, a vacuum is created in this section. And that's because the force of gravity pulls down on the liquid. But it will pull down to a certain extent. |
Using a Barometer .txt | Now, once you place it to the cup, a vacuum is created in this section. And that's because the force of gravity pulls down on the liquid. But it will pull down to a certain extent. And that's because the air molecules found on the outside, such as oxygen molecules, carbon dioxide molecules, nitrogen molecules, exert a certain force on these two sections here on this liquid. And when the force of these molecules equals the force of the gravity on the liquid, when these two forces equal, it will stop pulling down, and it will level off at some height H. So then you can calculate that height H from this point to this point. And you can use this formula to find the pressure of the atmosphere where pressure is equal to density of liquid times gravitational constant times height H.
So let's see what happens when the atmosphere pressure increases. |
Using a Barometer .txt | And that's because the air molecules found on the outside, such as oxygen molecules, carbon dioxide molecules, nitrogen molecules, exert a certain force on these two sections here on this liquid. And when the force of these molecules equals the force of the gravity on the liquid, when these two forces equal, it will stop pulling down, and it will level off at some height H. So then you can calculate that height H from this point to this point. And you can use this formula to find the pressure of the atmosphere where pressure is equal to density of liquid times gravitational constant times height H.
So let's see what happens when the atmosphere pressure increases. Suppose you decrease the altitude where you are measuring the pressure, so the pressure increases. If the pressure increases, then the force will increase. That's pushing down this liquid. |
Using a Barometer .txt | Suppose you decrease the altitude where you are measuring the pressure, so the pressure increases. If the pressure increases, then the force will increase. That's pushing down this liquid. It will push the liquid down lower and will raise this higher. So h will increase. And according to the formula, we see just that. |
Using a Barometer .txt | It will push the liquid down lower and will raise this higher. So h will increase. And according to the formula, we see just that. If the pressure has increased while these two guys are held constant, h will increase. The same is true for a lower pressure. Supposedly, go higher up to some mountain top. |
Using a Barometer .txt | If the pressure has increased while these two guys are held constant, h will increase. The same is true for a lower pressure. Supposedly, go higher up to some mountain top. At this mountaintop, the pressure is lower. So H will be lower as well, because these two guys are constant. And that's because if the pressure is lower, the force of gravity will be higher. |
Using a Barometer .txt | At this mountaintop, the pressure is lower. So H will be lower as well, because these two guys are constant. And that's because if the pressure is lower, the force of gravity will be higher. And so it will push this level up, and it will lower this level. Okay? So the height, the total height, will be lower. |
Using a Barometer .txt | And so it will push this level up, and it will lower this level. Okay? So the height, the total height, will be lower. Now, last thing I want to talk about is this little vacuum here. Now, remember, this liquid we chose, mercury, will evaporate some of its molecules. So, technically, this isn't a vacuum. |
Using a Barometer .txt | Now, last thing I want to talk about is this little vacuum here. Now, remember, this liquid we chose, mercury, will evaporate some of its molecules. So, technically, this isn't a vacuum. And there are some vapor molecules flowing around or flying around in this area in the space here. Now, what happens if we increase the vapor pressure here? If we increase the vapor pressure, the pressure due to the molecules in the air will push on this section here. |
Definition of Temperature .txt | In this lecture, I will talk to you about the concept of temperature. Now, temperature can be defined in many different ways. In this video, I've outlined three major definitions of temperature. The first definition talks about energy transfer. The second definition talks about the ideal gas law. And the third definition couples thermal energy or kinetic energy with temperature. |
Definition of Temperature .txt | The first definition talks about energy transfer. The second definition talks about the ideal gas law. And the third definition couples thermal energy or kinetic energy with temperature. Now let's go to the first definition. Now let's remember what heat is. Heat is a transfer of energy from a cold body to a hot body, which means that an energy transfer only occurs when there is a difference in temperature. |
Definition of Temperature .txt | Now let's go to the first definition. Now let's remember what heat is. Heat is a transfer of energy from a cold body to a hot body, which means that an energy transfer only occurs when there is a difference in temperature. So one way to define temperature is to say that temperature is a property of matter that determines if energy transfer can occur. That is, if there is no difference in temperature. If the temperature of one object and a second object are the same, no energy transfer due to heat can occur. |
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