Water, Ice and Hydrogen Bonding

Water has a relatively high boiling point due to the fact that it creates two hydrogen bonds (as it has two lone pairs). These require a lot of energy to break, hence the high boiling point.

Water has high surface tension and forms a meniscus because the hydrogen bonds pull the water surface downwards.

When water freezes into ice a whole network of hydrogen bonds form. The hydrogen bonds and covalent O-H bonds are arranged tetrahedrally around the O atom. The H2O molecules are kept apart to form a lattice by this arrangement, there is a lot of space in this structure - giving ice a lower density than water.