Diamagnetic

[Temperature101]

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Which of the folowing molecules or ions would be predicted to be diamagnetic?

A. He2-
B. N2
C. F2-
D. B2

 

[NuttyEngDude]

Diamagnetic means all the electrons are paired. So N2 has all of it's electrons in a pair:

N: 1s2 2p3
N: 1s2 2p3

All match up in pairs.

The others have an unpaired electron making them paramagnetic. For example He2(-) has its electrons all match up, but the extra electron (-) will be unpaired
He2(-) is:
He: 1s2
He: 1s2
(-) 1


It's kind of confusing without better diagrams but I think this works as an explanation, let me know if I just made it worse, lol.

 

[Temperature101]

Diamagnetic means all the electrons are paired. So N2 has all of it's electrons in a pair:

N: 1s2 2p3
N: 1s2 2p3

All match up in pairs.

The others have an unpaired electron making them paramagnetic. For example

He2(-) has its electrons all match up, but the extra electron (-) will be unpaired
He2(-) is:
He: 1s2
He: 1s2
(-) 1


It's kind of confusing without better diagrams but I think this works as an explanation, let me know if I just made it worse, lol.

Got it...p subshell has 6 electrons..Hence, in pair.

Can I do it that way as well...Let say N2 has 14 electrons. If I write the electronic configuration of N2, the last 2 electrons will fall in the 4s subshell.Therefore, they are in pair. Can I use this reasoning?

 

[NuttyEngDude]

Yes that is right. So long as you keep in mind the subshells you are ok. If you try to reduce it to just evens and odd # of electrons, that is a common trap.

 

[Trayshawn]

Where'd you get this question from? I didn't thnk the MCAT tested para/dimagnetism in molecules. That would require knowledge of molecular orbital building and filling which is certainly beyond the scope of the mcat.

I only know the mcat to test para/dimagnetism in single elements - often ions (like O^-2 or something)

 

[Temperature101]

Where'd you get this question from? I didn't thnk the MCAT tested para/dimagnetism in molecules. That would require knowledge of molecular orbital building and filling which is certainly beyond the scope of the mcat.

I only know the mcat to test para/dimagnetism in single elements - often ions (like O^-2 or something)

Got it from a TPR FL. There was a whole passage about molecular orbital building and this question was one of the questions from the passage..I guess It is part of the mcat. You better review these concepts now.

 

[richkaj]

If it is on the MCAT, they should provide a molecular orbiting table to see if an molecule has bonding or antibonding orbitals... this will determine if the molecule is para or diamagnetic. Osub2 (oxygen) has even numbers of electrons but it is paramagnetic. You must use the scale by filling in the electrons in each atom... Hope this helps.

 

[Temperature101]

If it is on the MCAT, they should provide a molecular orbiting table to see if an molecule has bonding or antibonding orbitals... this will determine if the molecule is para or diamagnetic. Osub2 (oxygen) has even numbers of electrons but it is paramagnetic. You must use the scale by filling in the electrons in each atom... Hope this helps.

They provide the table...The table wont help you in answering this particular question..

 

[richkaj]

Using Hund's rule for each element on each side of the table fill in the electron orbitals. Finishing with both sides of the equation. Fill in the middle section using Hund's rule. Those that are paired are diamagnetic, those that are not paramagnetic.