Sigma, Pi bonds

Sigma σ bond: covalent bond where overlap region lies on line connecting nuclei (internuclear axis)

Pi π bond: covalent bond where overlap region lies above and below internuclear axis (created from non-hybridized orbital overlap)

(occurs w/ sp and sp² hybridization only)

Single bond:     σ only

Double bond:    1 σ and 1  π  bond

Triple bond:     1 σ  and 2 π  bonds

C₂H₄

e- config

orbital diags

pict

localized π bonds: σ  and π bonds assoc. totally w/ 2 atoms that form bond

delocalized π bonds: π bonds assoc. w/ neighboring atoms, not just 2 atoms that form bond

(occurs in molecules that exhibit resonance)

Benzene C₆H₆