Covalent bonding in Methane: CH4
Carbon: 1S2 2S2 2P2
Energy is released as carbon forms covalent bonds and the more
energy released the more stable the molecule. If the 2S electron is
promoted to 2P then 4 unpaired electrons can be used in bonding:
In methane, all four C-H bonds are identical, so the
electrons in the S and P orbitals rearrange themselves
in a process called hybridization
hybridization
The SP3 orbitals are tetrahedral in shape to avoid electron
repulsion between orbitals and this defines the shape of
CH4 where it can bond with 4 hydrogen atoms. Bond
angle 109o
H
H C 109
H
H
In ethane, C2H6 there are 4 SP3 orbitals for each carbon
atom available for bonding;
Three between C and H and the remaining one between C
and C forming a sigma (s) bond:
Ethene, CH2CH2 has a different bonding structure:
Three of the 2S and 2P electrons are hydridized
this time, to leave a 2P orbital. Then three SP2
hybrids form:
Before C=C bonding
Bonds forming (molecular orbitals)