The electronic structure of carbon

Carbon has six electrons. Two of them will be found in the 1s orbital close to the nucleus. The next two will go into the 2s orbital. The remaining ones will be in two separate 2p orbitals. This is because the p orbitals all have the same energy and the electrons prefer to be on their own if that's the case.

The electronic structure of carbon is normally written 1s²2s²2p_x¹2p_y¹.