Why Water Expands When It Freezes

From most of our experiences, liquids contract when they freeze. Except of course for water. Water contracts for a little while when freezing and then expands.


The Structure Of A Water Molecule

The Oxygen-Hydrogen bond is formed through covalent bonding.
Oxygen(red) is significantly more electronegative-(an atom's ability to attract electons)- than hydrogen(blue). Thus, oxygen attracts a lot more of the electron cloud. As such, in a water molecule, the oxygen atom is partially negative whiles the hydrogen atoms are partially positive.