[sandave003]

carbanion can be notated by carbon with 3side bonds and a pair of electrons with (-) sign. One thing i know it can accommodate 4 electron; 2 electrons goes to regular bonding molecular orbital other two electrons? and what does it mean in this state carbon contains 10 electrons with it? please explain

[cth]

Carbon atoms have the electronic configuration 1s²2s²2p².

Carbanions are carbon atoms with one extra electron (therefore they are not electrically neutral anymore, they have -1 electric charge). So their configuration becomes 1s²2s²2p³.

You can notice that it is the same electronic configuration than nitrogen 1s²2s²2p³. And just like nitrogen, carbanions have one lone pair and can form three sigma bonds.

Contrary to nitrogen, carbanions are not stable, except in particular cases where they are stabilised by resonance. They are very reactive species.

One thing i know it can accommodate 4 electron; 2 electrons goes to regular bonding molecular orbital other two electrons? and what does it mean in this state carbon contains 10 electrons with it?

I am not sure I understand what you mean. Sorry if I answer outside your question:
A carbon atom with 10 electrons is normal when the atom is bonded within a molecule. For example, let's consider methane CH₄. Electronic configuration of atomic carbon: 1s²2s²2p². So, if you include the core electrons in 1s, you have 6 electrons in total. Now, each hydrogen bring his own electron to share with the carbon. Four hydrogen atoms give four extra electrons  6+4=10 electrons for the carbon. It is the same for carbanions.

This is a consequence of the octet rule http://en.wikipedia.org/wiki/Octet_rule. For elements C, N, O, F and Ne with filled 2s and 2p orbitals, you have: 8 valence electrons + 2 core electrons in the orbital 1s = 10 electrons in total.

Is it what you were asking?

[sandave003]

thanks for reply ,

carbanion can accommodate 4 electrons; two in regular molecular orbital and other 2 in antibonding orbitals of higher energy.--this was needed to be explained ,kindly.

for carbocation it does mean it contains only 3 electrons in outer most shell, if so ,in excited state only px and py will be filled , this explain.

[cth]

carbanion can accommodate 4 electrons; two in regular molecular orbital and other 2 in antibonding orbitals of higher energy.--this was needed to be explained ,kindly.

OK, I understand your question now. 
We need to look at the molecular orbital diagram to know where the electrons go.

First, we need to draw the MO diagram of CH₃^-. Let's look at the picture hereafter, from http://www.ch.ic.ac.uk/vchemlib/course/mo_theory/main.html for the ammonia NH₃ diagram, middle of the page (are you OK with this diagram?):

CH₃^- MO diagram is very similar to NH₃. The biggest difference is that carbon atoms are less electronegative than nitrogen, so their atomic orbitals are a bit higher in energy.

You have two electrons in the non-bonding MO 2a₁.
The three anti-bonding MOs 3a₁ and 2e are empty.