Explain the structure of water.

(N/A) In the gas phase, water is a bent molecule with a bond angle of $104.5^{\circ}$ and an $O-H$ bond length of $95.7 \text{ pm}$.
It is a highly polar molecule due to the electronegativity difference between oxygen and hydrogen atoms.
In the liquid phase, water molecules are associated together by hydrogen bonds.
The crystalline form of water is ice. At atmospheric pressure, ice crystallizes in the hexagonal form, but at very low temperatures, it condenses to a cubic form.
The density of ice is less than that of water, which is why an ice cube floats on water.
In the winter season, ice formed on the surface of a lake provides thermal insulation, which ensures the survival of aquatic life.