VSEPR: predicting shapes with AXnEm

The valence electron pairs of the central atom arrange themselves so as to minimise their repulsions. The label is $\text{AX}_n\text{E}_m$: A the central atom, $n$ the number of bonded atoms, $m$ the number of lone pairs on A. A double or triple bond counts as one domain; $n + m$ is the number of electron domains.