bond orders

[Guest minyng]

What are the bond orders in H2, H2+, and H2- respectively based on molecular theory

 

thanx guyz

[Yggdrasil]

Bond order is equal to (the number of electrons in bonding orbitals - the number of electrons in antibonding orbitals)/2. In a diatomic hydrogen molecule, there is one bonding orbital (which holds two electrons) and one antibonding orbital (which holds an additional two electrons). Because the bonding orbital has a lower energy, you fill that one up first before electrons are added into the antibonding orbital.

 

In H₂, each hydrogen contributes two electrons which both go into the bonding orbital. The bond order is 1.

 

H₂⁺ is lacking an electron, so its one electron goes into the bonding orbital. The bond order is 1/2.

 

H₂^- has an extra electron. The first two electrons fill the bonding orbital, so the third goes into the antibonding orbital. The bond order is therefore 1/2 [(2-1)/2]