Be2 and Ne2 molecule does not exists as it has zero bond order. It is calculated as, Molecular orbital electronic configuration of Be2 molecule =KK(σs)2(σ*2s)2 Thus bond order =
2−2
2
=0 Molecular orbital electronic configuration of Ne2 molecule =KK(σ2pz)2(π2px)≃(π2pyy)2,π*(2px)2≃(π*2py)2,(σ*2pz)2 Bond order =