I am refreshing on bonding and structure before starting an organic chem class. I am a bit rusty on hybrid orbitals in bonding. Take Methane, CH4, I understand each carbon has an sp3 orbital that overlaps an s orbital on the H to form its 4 bonds. In a CCL4 atom, which is also sp3 hyrbidized each carbon uses an sp3 orbital to bond to each Cl but which orbital of the Cl atom does the carbon orbital overlap?

3 answers

17Cl is 1s2 2s2 2p6 3s2 3p5 so what does Cl need to complete its octet?
If I am understanding correctly what you are asking, the 3p orbital can only hold 6 electrons and here it has 5 so it needs 1 more to complete its octet? It would accept 1 electron from the carbon?

So the carbon is the one with the hybridized orbitals. The Cl orbitals don't get hybridized and since the 3p orbital can accept 1 more electron that is the orbital that overlaps with the sp3 of the carbon?
yes. Although I wouldn't go so far as to say the chlorine ACCEPTS an electron from the carbon. I would prefer to say that one electron from the Cl and 1 from the C were shared to form a C:Cl covalent bond. The bond will be somewhat polar because of the difference in electronegativity of C and Cl. Of course 4 Cl atoms do this with the 4 available electrons of C to form the CCl4 molecule. The C atom has a tetrahedral structure because of the sp3 hybridized orbitals with the 4 Cl atoms hanging on at the four corners of the tetrahedran with covalent bonds. By the way, I'm sure you understand that each C-Cl bond is slightly polar but the CCl4 molecule as a whole does not have a dipole moment because it is symmetrical. That is, the individual dipole moments of the 4 C-Cl bonds cancel each other because of symmetry in space. Thanks for using Jiskha.