What is the electronic configuration of carbide C-4?

Question

Thought it was 1s2 2s2 sp2.

Thanks from Sheryl

C is atomic number 6.
Electronic configuration of the neutral atom is 1s2, 2s2, 2p2.
The carbide ion, C^-4, has four more electrons. So the extra four electrons must be added. Where do you think they go?

4 extra valance electrons.

That's the only way it can be C^-4. Now where do they go? What is the electron configuratiion.

1s2 2s2 2p6? I must have been thinking we were doing the periodic table.

Right. And note that the addition of 4 electrons make a full N = 2 level with 8. Note also that the loss of 4 electrons (remember C is in group IV so it can gain four or lose four) it has 1s2 2s0 2p0; i.e., the outside shell (which is now n= 1) is full with its two electrons.

And note also that since C is in group IV and can "gain or lose four electrrons" it usually does neither and shares its electrons in covalent bonds.