We present a description of the valence bonding in solid hydrogen under pressure, through ab initio valence bond calculations on a small cluster. Our results show a huge increase in charge transfer components of the ground state wave function at intermolecular separations around 1.7 Angstrom. This provides an explanation, in terms of chemical bonding, for the origin of the observed modifications in the structural and electronic properties of solid hydrogen at that intermolecular separation range.