Why water expands on freezing?
The reason why water expands upon freezing is due to the intermolecular forces of attraction which exist between the water molecules, in particular, Hydrogen Bonding. Water (H2O) is a polar molecule, the Oxygen side gaining a partial negative charge and the Hydrogen side gaining a partial positive charge. The partially positive Hydrogen’s in a water molecule are attracted to partially negatively charged Oxygen’s in other water molecules. It is this intermolecular attraction (called Hydrogen bonding) which gives water many of its unusual properties. As a matter of fact, without Hydrogen bonding, water would be a gas at room temperature, not the liquid we are all familiar with. As water freezes, the molecules begin to slow down. As the molecules slow down they become less and less able to break free of these attractive forces and begin to align themselves in a position which takes the least energy. Due to the geometry of the water molecule, this least energy position forms a lattice that
