Why do atomic orbital need hybridization? H20 A first approximation to the valence-bond description of bonding in an H,O molecule. Each o bond arises from the overlap of an H1s orbital with one of the O2p orbitals.This model suggests that the bond angle Use of should be90°，which is p-orbitals significantly different from the experimental value.Use of p - orbitals H2O Why do atomic orbital need hybridization? A first approximation to the valence-bond description of bonding in an H2O molecule. Each  bond arises from the overlap of an H1s orbital with one of the O2p orbitals. This model suggests that the bond angle should be 90, which is significantly different from the experimental value