How do I determine the bond order of Mg2?

The question indicates:

(sigma3s), (sigma3s)*, (pi3p), (pi3p)*, (sigma3p)*; in other words, the (sigma2s) to (sigma2p)* pattern is repeated.

1 Answer

  • This is the same as a second period diatomic analogous to Be2:

    MO diagram with no sp mixing (it doesn’t matter if we have sp mixing or not)

    Mg [Ne] 3s^2

    Mg2 = 4e⁻= 3σs(2e⁻) 3σs*(2e⁻) 3σp(0) 3πp(0e⁻) 3πp*(0e⁻) 3σp*(0e⁻)

    Bond Order = ½[Σ (bonding e-) – Σ (antibonding e-)]

    bo = ½[ {σs(2e⁻)} – {σs*(2e⁻)}] = 0

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