Molecular Orbital Diagram: Period 2 Heteronuclear Diatomics

Pick any two elements, from period-2 Li–F or hydrogen, to see the full valence MO diagram for that pair. Unequal atomic energies pull each molecular orbital towards whichever atom it sits closer to in energy, so both the diagram and the orbital shapes come out polarised. Hydrogen has only a 1s orbital, and Li/Be's empty, high-energy 2p is excluded here too, so any pair involving H, Li or Be has a smaller diagram, as the teaching notes explain. Click any level to see that orbital's shape.

Atom A

Atom B

C–O

valence electron configuration

—

bond order

magnetism

diamagnetic

bond length

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s–p mixing

MO energy-level diagram click a level to see its shape (valence 2s/2p only; 1s for H, 2s only for Li/Be)

Selected orbital: σ(2s) ψ = …

bonding MO antibonding MO non-bonding MO (pairs involving H, Li or Be) nodal surface (ψ = 0) ↑ ↓ electrons, filled by the Aufbau principle + Hund's rule extra σ(2s)–σ(2p) / σ*(2s)–σ*(2p) interaction (s–p mixing, when on) correlation-line strength ∝ how much of that MO sits on that atom