[elizabeth86]

I am somewhat confident with orbital hybridisation, but I can't seem to grasp the orbital hybridisation of carbon in carbon dioxide. It's a linear molecule, which would indicate that it would be sp (right?). But the orbitals are like this:
C - 1s2 2s2 2p2    O - 1s2 2s2 2p4
so I would think it would be an sp3?
Can anyone help explain this to me? (And yes, I've read many websites and still don't get it)

[Rabn]

The carbon atom needs to hybridize itself into 4 sp orbitals, each orbital needs to have 50% s character and 50% p character in order for the bond to be linear. The oxygen then hybridizes its 2 half full p orbitals and its full 2s orbital into 2 sp orbitals. They would look like this

Carbon
1s2, 2sp4

oxygen
1s2, 2sp2(not to be mistaken for sp²),2p4

Now as to the why...how to explain it properly...think about it this way. The more electronegative atom when two approach for bonding wins, by wins I mean it controls what happens. So there are 2 oxygens that each needs 2 electrons, they will do as little work as necessary to make that happen. What they will do is promote 1 2s2 electron to the p orbital leaving a half full 2s orbital and a half full 2p orbital which hybridize to form 2 2sp orbitals.  The carbon simultaneously promotes 1 of its 2s2 electrons into the p orbital leaving each orbital in the second shell half full, these will hybridize into 4 2sp orbitals. Let me know if that helps at all.