Chemical Bonding

1 · Formulas and when each holds

• Bond order (MOT) = ½(bonding − antibonding electrons).
• Hybridisation: count σ bonds and lone pairs on the central atom.
• Dipole moment is a vector: symmetric shapes cancel.

2 · Question types and the first step

• Shape questions: count electron pairs, then name the geometry, then the shape.
• Magnetic behaviour: write the MO filling and look for unpaired electrons.

3 · Traps

O₂ is paramagnetic: two unpaired electrons in π* orbitals.

4 · My additions

• s-p mixing changes the order for B₂, C₂, N₂.