Molecular Shapes

A Lewis structure says which atoms are joined, but molecules are three-dimensional, and their shapes decide almost everything: why water is a liquid, why carbon dioxide is a gas, how a drug fits its target. Build shapes from repelling electron pairs and turn them with your finger, watch lone pairs squeeze bond angles, add up bond dipoles to see whether a molecule is polar, mix orbitals into hybrids, and fill molecular-orbital diagrams to find out why liquid oxygen sticks to a magnet.