[Sheryl]

According to a question I must answer, C and O anions with a negative charge of minus one have been observed. Maybe they do not occur in nature. I need to know why it is not possible to have or to make an N ion with a single negative charge but it is for O and C. It has to do with electron configuration.

The exact question is:
"Why has it not been possible to date to make a N- ion when C- and O- have been observed? Explain it terms of electron configuration of the atoms mentioned."

I've spent hours looking for this on the internet and am not getting anywhere with it. Any help appreciated.

Sheryl

[Mitch]

N- has been made. It takes 7 kJ/mol. Just look up the electron affinity of nitrogen.

[Sheryl]

The instructor said that if it's been made, we need to ignore it and act as if it hasn't.  Anyhow, I have to answer the question regardless of whether it's been made or not.

Sheryl

[Mitch]

Why don't you actually write the electron configuration for us.

[Sheryl]

Electron configuration for nitrogen is [He] 2s2 2p3

[Mitch]

and adding an extra electron will force it to pair up with an other electron, causing something called the pairing energy

[Sheryl]

We haven't had pairing energy yet.  I'm in college general chemistry first quarter.  

I'm thinking of two alternatives at this point.  One is, any free nitrogen molecule would pair with another creating a triple bond and giving it a noble gas configuration.  Mabye they monopolize each other so they can't form other ions.  The other is that N has its 2p shell half-filled.  Since all the orbitals will be of the same polarity, there will be an electron repulsion and perhaps that prevents adding another electron to form a minus one charge anion.  Apparently it will not prevent it from accepting three of them.  I suppose the nuclear charge imperative could be taking over.

Any thoughts appreciated.

Sheryl

[Mitch]

Yeah, I'm pretty sure its the pairing energy.

[Sheryl]

Okay, I'm going with pairing energy.  Thank you for that direction.  Another question about the same matter.  

Nitrogen  (2s2 2p3) has all p orbitals half-filled and so there is electron-electron repulsion making it less likely to accept another electron.

Carbon ((2s2 2p2) has an unfilled orbital so is apparently more likely to accept an electron than Nitrogen.

Why is Oxygen (2s2 2p4) more likely to accept an electron than Nitrogen?  This is essentially what is being said in the question asked, that minus one C and O ions have been observed but not N (untrue but no choice on that matter.)

Much appreciation,

Sheryl