The water molecule and hydrogen bonding

Almost everything unusual about water follows from one fact: the molecule is bent, so its charge is not evenly distributed.

Polarity: The bent shape means the bond dipoles do not cancel. Carbon dioxide, which is linear, is not polar despite having polar bonds.
Hydrogen bonding: About a twentieth the strength of a covalent bond, but there are so many that they dominate water’s behaviour.
Why ice floats: Hydrogen bonds hold molecules in an open tetrahedral lattice when frozen, which is less dense than liquid water. Almost no other substance does this — and lakes freezing from the top down depends on it.
Universal solvent: The polar molecule surrounds and separates ions, which is why water dissolves more substances than any other common liquid.

Text description

A water molecule has an oxygen atom bonded to two hydrogen atoms at an angle of about 104.5 degrees. Oxygen pulls electron density toward itself, giving it a partial negative charge and each hydrogen a partial positive charge. Because the molecule is bent rather than linear, these do not cancel, so the molecule is polar. The partial positive hydrogen of one molecule is attracted to the partial negative oxygen of another, forming a hydrogen bond. Each molecule can form up to four.