At 9:36, for the Hydrogen Peroxide example, if the oxygen is receiving an electron from the hyrdogen wouldn't oxygen's oxidation number be '-1' as opposed to '+1' as seen in the video?
When the going gets tough, I just sit there with a dumb expression on my face listening to your voice. Very helpful! I've learned more in 17 minutes than 3 weeks!
You are correct. My brain must have heard itself say "gaining" and put +1 there. I've added annotations to correct. Will also make a follow-on video to make sure people are not confused.
@lykranian The Oxide atoms react with one another therefore they both 'lose' an electron. Eventually both of the oxide atoms will have a charge of -1 making the total charge 1(2) + -1(2) = 0
The magnesium hydroxide: Mg+2 becuase it gives up 2 electrons H+1 is bonded to the O, so it had to give up 1 electron O-2 because it gains 2 electrons 2 at end of equation because there are 2 OH and the one OH is -1, therefore making the OH -2 and Mg +2 is cancelled out ??
IF all carbons are created equal... than why is one green and one orange? you racist!! lol sal you are one one of the most amazing persons in this world!
1. MgO is not molecular. There are no molecules of MgO. MgO is a network solid, with alternating Mg and O atoms going off in three dimensions. Mg does not "want" to lose 2 electrons. It has no wants. But removing two electrons from Mg requires energy, lots of it. It's called the ionization energy. Electrons just don't "fall off" of an Mg atom. Nor does O want to gain 2 electrons. It will actually get to a lower energy by gaining one electron, but that will form an atom with a net -1 charge. It then requires energy to "push" a second electron onto O^- since the negatively charged atom and an electron both have the same charge and repel. MgO forms because the Mg nucleus is attracted to the electrons of the nearest six oxygen atoms and each oxygen is attracted to the electrons of the nearest six Mg atoms, forming a lattice of Mg and O atoms, all mutually attracted to each other. 2. There is no "giving up" of an electron from hydrogen to oxygen. The H-O bonds in water are highly covalent. As is often used in describing covalent bonding, the electrons are shared, not transferred. 3. There is no such compound as iron(III) carbonate. It simply does not exist. That is because as the oxidation state of a metal increases it becomes more and more acidic. Iron(III) is too acidic for the carbonate to be stable. Bringing CO3^2- together with Fe3+ in water will cause the CO3^2- to decompose to form CO2 gas, and OH- ions will form producing insoluble Fe(OH)3. This is fundamental chemistry that a chemist would know, but Khan apparently doesn't. 4. When carbon combines with oxygen, whether to form CO, as I discussed, or the carbonate ion, CO3^2-, it does NOT give four electrons to oxygen. The bond between carbon and oxygen is highly covalent and carbon does NOT take on a charge of +4. That is nonsense. Khan is making a rookie mistake. He is equating the oxidation number of an atom in a compound with an ionic charge. The atoms in compounds may have slight charges due to differences in electronegativity, at most about +1 or -1, and usually some fractional value. Oxidation number is a mathematical construct. It is the hypothetical charge on an atom assuming that the bonds are 100% ionic. BUT!!! There are no 100% ionic bonds, and the oxidation numbers of atoms in compounds do not reflect any actual charge. Oxidation numbers are useful for naming compounds (the Stock system) and for simplifying redox reactions, but they are not meant to reflect the literal gain or lose of electrons in bond formation.
Not quite sure where you got the idea that MgO is a network solid, that would imply that it's a molecule which, as you stated, isn't the case. MgO is an IONIC compound because the difference in electronegativity between the Magnesium and Oxygen atoms exceed 1,7 on the Pauling scale. Maybe you hadn't realized but Khan is designed to cover the basics of science, math, etc. When he mentioned the 'giving up' of electrons, he didn't actually mean it. Not sure if it's in this video, but he talks about the how scientists created this protocol to avoid giving the atoms partial charges because it was much simpler to consider them as full charges. It makes sense, really. It's much simpler to consider the bonds as ionic because you can directly find the oxidation state of the given atom from there.
Sure, it's always a good idea to say things to students that we really don't mean and that really aren't true. A network solid is an arrangement of atoms in a regular array. In the case of MgO we have an array of alternating Mg and O atoms in three dimensions. The bonds between between Mg and O atoms are polar, with 68% ionic character. Mg and O atoms actually don't have full charges of +2 and -2. I don't really think that offering oversimplifications as "reality" is a good idea. What's wrong with "partial charges?"
Mike Jones There's one main explanation that I can offer for overlooking the partial charge and considering it a full one: One can directly find the oxidation state just by knowing the charge. Once again, you're looking at an introductory video on redox..nobody with your wealth of knowledge should waste their time on the oversimplification of redox.
+Mike Jones Sal Khan is probably smarter than both you and me, and so i think we should realise that he is making it simpler, and more fun - It's important that it's fun. I know that when atoms combine to form molecules, salt, etc., it's the sub-orbitals and orbitalts with different energies that overlap each other to reach a new, stable form of the molecule or salt, which we can use in our everyday life. However, i tend to pretend that Electrons are crying babies which reduce atoms by wrecking their life in pieces when recieved. What's wrong with a little simplification if you know the truth ? :))
At 9:36, for the Hydrogen Peroxide example, if the oxygen is receiving an electron from the hyrdogen wouldn't oxygen's oxidation number be '-1' as opposed to '+1' as seen in the video?
Yes
I have the same doubt too.. I think it is -1 and cuz there's 2 oxygens -2 and the oxidation states are cancelled
When the going gets tough, I just sit there with a dumb expression on my face listening to your voice. Very helpful! I've learned more in 17 minutes than 3 weeks!
You are correct. My brain must have heard itself say "gaining" and put +1 there. I've added annotations to correct. Will also make a follow-on video to make sure people are not confused.
in a neutral compound the o.s add to 0 not 1
I think this just saved my chemistry midterm grade. THANK YOU.
At 2:11, all oxidation states are to add up to 0, not 1 :)
Umm what about oxidation states of polyatomic ions? Thats what i thought.
So picky bruh lol
You're so much better than my teacher! Thank you so much!
@Mslivecode He mentions it in the video. Carbon can be either +4 or -4, depending if it is bonded with elements on the right or left of it.
I've learned more in 10 minutes that I did in a whole year.
Excellent tutorial thank you a lot for your help
great video
@lykranian The Oxide atoms react with one another therefore they both 'lose' an electron. Eventually both of the oxide atoms will have a charge of -1 making the total charge 1(2) + -1(2) = 0
@Avatarass He meant to put 4 + 3(-2) = -2 at 12:08, since you add the oxidation states of each atom.
The magnesium hydroxide:
Mg+2 becuase it gives up 2 electrons
H+1 is bonded to the O, so it had to give up 1 electron
O-2 because it gains 2 electrons
2 at end of equation because there are 2 OH and the one OH is -1, therefore making the OH -2 and Mg +2 is cancelled out ??
At 10:06, in H2O2 shouldn't the oxidation state of Oxygen be -1 each ?
Excuse me what level is it suposed to be like ten grade or what
What are oxidation states of f-block?
@Avatarass it should be +4 + 3(-2). Sal got the + and - confused.
IF all carbons are created equal...
than why is one green and one orange?
you racist!!
lol
sal you are one one of the most amazing persons in this world!
At 8:45 the H2O2 would have a total charge of -2, right? 1(2) + -2(2) = -2.
In 12:17, will it not be +4+3(-2)?
Because according to the video, it should be +4+6 then, since negative multiplied with negative gives positive.
Thanks
I am now an oxidation state jock!
you make khans proud
When he is talking about Fe2(CO3)3 how doe she know that the oxidation state of C is +4
Thank you very much :)
;) :) soo good ...thank you!!
12:18 wait shouldn't it be +4 + 6??
It's supposed to be 4 + 3*(-2)
Which equals -2
He made a mistake
khanacademy is the best
1. MgO is not molecular. There are no molecules of MgO. MgO is a network solid, with alternating Mg and O atoms going off in three dimensions. Mg does not "want" to lose 2 electrons. It has no wants. But removing two electrons from Mg requires energy, lots of it. It's called the ionization energy. Electrons just don't "fall off" of an Mg atom. Nor does O want to gain 2 electrons. It will actually get to a lower energy by gaining one electron, but that will form an atom with a net -1 charge. It then requires energy to "push" a second electron onto O^- since the negatively charged atom and an electron both have the same charge and repel. MgO forms because the Mg nucleus is attracted to the electrons of the nearest six oxygen atoms and each oxygen is attracted to the electrons of the nearest six Mg atoms, forming a lattice of Mg and O atoms, all mutually attracted to each other.
2. There is no "giving up" of an electron from hydrogen to oxygen. The H-O bonds in water are highly covalent. As is often used in describing covalent bonding, the electrons are shared, not transferred.
3. There is no such compound as iron(III) carbonate. It simply does not exist. That is because as the oxidation state of a metal increases it becomes more and more acidic. Iron(III) is too acidic for the carbonate to be stable. Bringing CO3^2- together with Fe3+ in water will cause the CO3^2- to decompose to form CO2 gas, and OH- ions will form producing insoluble Fe(OH)3. This is fundamental chemistry that a chemist would know, but Khan apparently doesn't.
4. When carbon combines with oxygen, whether to form CO, as I discussed, or the carbonate ion, CO3^2-, it does NOT give four electrons to oxygen. The bond between carbon and oxygen is highly covalent and carbon does NOT take on a charge of +4. That is nonsense.
Khan is making a rookie mistake. He is equating the oxidation number of an atom in a compound with an ionic charge. The atoms in compounds may have slight charges due to differences in electronegativity, at most about +1 or -1, and usually some fractional value. Oxidation number is a mathematical construct. It is the hypothetical charge on an atom assuming that the bonds are 100% ionic. BUT!!! There are no 100% ionic bonds, and the oxidation numbers of atoms in compounds do not reflect any actual charge. Oxidation numbers are useful for naming compounds (the Stock system) and for simplifying redox reactions, but they are not meant to reflect the literal gain or lose of electrons in bond formation.
Not quite sure where you got the idea that MgO is a network solid, that would imply that it's a molecule which, as you stated, isn't the case. MgO is an IONIC compound because the difference in electronegativity between the Magnesium and Oxygen atoms exceed 1,7 on the Pauling scale. Maybe you hadn't realized but Khan is designed to cover the basics of science, math, etc. When he mentioned the 'giving up' of electrons, he didn't actually mean it. Not sure if it's in this video, but he talks about the how scientists created this protocol to avoid giving the atoms partial charges because it was much simpler to consider them as full charges. It makes sense, really. It's much simpler to consider the bonds as ionic because you can directly find the oxidation state of the given atom from there.
Sure, it's always a good idea to say things to students that we really don't mean and that really aren't true. A network solid is an arrangement of atoms in a regular array. In the case of MgO we have an array of alternating Mg and O atoms in three dimensions. The bonds between between Mg and O atoms are polar, with 68% ionic character. Mg and O atoms actually don't have full charges of +2 and -2. I don't really think that offering oversimplifications as "reality" is a good idea. What's wrong with "partial charges?"
Mike Jones There's one main explanation that I can offer for overlooking the partial charge and considering it a full one: One can directly find the oxidation state just by knowing the charge. Once again, you're looking at an introductory video on redox..nobody with your wealth of knowledge should waste their time on the oversimplification of redox.
The point is to get it right!!!!
+Mike Jones Sal Khan is probably smarter than both you and me, and so i think we should realise that he is making it simpler, and more fun - It's important that it's fun.
I know that when atoms combine to form molecules, salt, etc., it's the sub-orbitals and orbitalts with different energies that overlap each other to reach a new, stable form of the molecule or salt, which we can use in our everyday life.
However, i tend to pretend that Electrons are crying babies which reduce atoms by wrecking their life in pieces when recieved.
What's wrong with a little simplification if you know the truth ? :))
@v24094 actually not necessarily true. Isotopes. LOL~ anyway i like it
Isn't the oxidation state supposed to be +2 or -2 and the charge 2- or 2+?
yeah
i jus realised I was 3 years old when u commented.. it's so fascinating 💀💀like I never knew this shi existed then and u were studying it
@@shelbydonata_ well this takes me back to being 17 😂 Good luck with your studies!
@@_reeshu_ yesss thank you soo much.. good luck with everything you have going on toooo
acetic acid is ethanoic acid?
Yup. This is an informal name for it. Ethanoic Acid is in the IUPAC rules.
Did he make a mistake explaining hydrogen peroxide?
There are quite a few careless mistakes in your video , please rectify it :)
Other than that , it was really helpful, thanks!
how?
@Mslivecode because if C's valency
lol alll right im an oxidation state jock!
Way too complicated!!
Mg+2(O-2H+1)2 ??
NOMENCLATURE PLEASEEEE!!!!! :D
i get lost in the words wayyyy too wordy for me to understand
Good luck with 2-hour lectures at uni then aha
This is too long to pay attention too.
Scrap that stupid comment.
KHANtribution!
towards the end, carbons don't have a big enough electronegativity difference with hydrogen to create partial charges right?
I don't understand the oxidation states in h20 aqueous solution... Any help?
How do you know that H2O2 is a neutral molecule? Is that something I memorize or is it because each element has a 2 after it
@rinwhr no, the final is correct, but the original should be
+4+6(-2)
so how come the Carbon to Carbon bond in Acetate doesn't count?
Thank you so much for this, it all makes sense now. I don't know what I would do without you Sal :)
i just love your videos you made organic chemestry too easy for me thaaaaaaanx
thank you so much
sup
tarun
@lykranian 8:24 oops