Formation of an ethene (ethylene) molecule on the basis of sp2 hybridization :
i. Ethene molecule (C2H4) has two carbon atoms and four hydrogen atoms.
ii. The ground state electronic configuration of C (Z = 6) is 1s2 2s2 \(2p_x^1\) \(2p_y^1\) \(2p_z^0\).
Electronic configuration of carbon :
iii. One electron from 2s orbital of each carbon atom is excited to the 2pz orbital. Then each carbon atom undergoes sp2 hybridization.
iv. One ’s’ orbital and two ‘p’ orbitals on carbon hybridize to form three sp2 hybrid orbitals of equal energy and symmetry.
v. Two sp2 hybrid orbitals overlap axially two ‘s’ orbitals of hydrogen to form sp2 -s σ bond.
The unhybridized ‘p’ orbitals on the two carbon atoms overlap laterally to form a π bond.
Thus,
The C2H4 molecule has four sp2 -s σ bonds, one sp2 -sp2 σ bond and one p-p π bond.
vi. Each H-C-H and H-C-C bond angle in ethene molecule is 120°. All the six atoms in ethene (ethylene) molecule are in one plane.
Geometry of the molecule at each carbon atom is trigonal planar.
