Chemical Bonding & Molecular Structure — 5 Must-Know Facts — Summary

$O_{2}$ is paramagnetic (bond order = 2, two unpaired $e^{-}$ in π*2p) — MOT predicts this correctly; VBT does not.
Steric number = σ bonds + lone pairs determines hybridization; the molecular shape is obtained after removing lone pairs.
$XeF_{2}$ is linear ( $sp^{3}$ d, 3 lone pairs equatorial); $XeF_{4}$ is square planar ( $sp^{3}$$d^{2}$ , 2 lone pairs both axial).
Zero dipole moment requires symmetric geometry with no lone pair on the central atom (C $O_{2}$ , $BF_{3}$ , $CCl_{4}$ , $SF_{6}$ ).
MO filling order switches at Z = 7/8 boundary: $N_{2}$ has π2p before σ2p; $O_{2}$ has σ2p before π2p.