Animation of the structure of a molecule of water (H2O). This molecule has a bent geometry, with two hydrogen atoms (white) forming a shallow V with a central oxygen atom (red). This geometry is adopted as the hydrogen atoms repel each other, but the oxygen atom also contains two lone pairs of electrons, which also repel the hydrogens. The black arc shows the angle between the atoms. See clip K004 3556 for the molecule showing the lone pairs, and K004 3562 for the molecule without this angle.