ICE CRYSTAL: water molecules in ice

water image # 5 (ICE): picture showing water molecules in an ice crystal. This image is 500 x 500 pixels; the original image is 4096 x 4096 pixels. ICE: water is a highly polarised molecule which leads to hydrogen bonding among adjacent molecules. These hydrogen bonds link water molecules together in a crystalline array in the solid phase of water that is called ice. In ice, each water molecule bonds to four others in a fashion that is less dense than the constantly shifting molecular packing of water molecules in liquid water. This is why ice floats on water and creates giant floating ice sheets and icebergs. The fact that ice floats has implications for convection in the oceans and other bodies of water. Expansion on freezing creates problems when water is confined (e.g. pipes bursting in freezing weather). Water freezes into ice at 0^o (zero degrees Celcius) at sea level pressures and it boils at 100^o (one hundred degrees Celcius).

ANTIFREEZE: chemical that makes it more difficult for water to freeze (i.e. it drops the freezing/ melting point). Used in cars to prevent radiators from bursting.

In the molecules above, the central oxygen atom (red) is pictured as a sphere drawn at the scale of its covalent radius just touching two hydrogen atoms (green) drawn at the scale of their covalent radii. The transparent spheres represent the "surfaces" of each molecule and are created from the van der Waals radii of the constituent atoms.