While on this molecule, or actually atom, our lowest unoccupied molecular orbital is the one S orbital. Because we're missing an electron, we have a cat ion. So we have an MP, one S orbital. So this is our lumo, or lowest unoccupied molecular orbital. So when these two orbitals interact, so we have the SP three interacting with the one S, and we form the following two orbitals. We form the bonding molecular orbital and the anti bonding molecular orbital.