Question

Why ice is lighter than water?

Answer 1

Water

• Water molecules have a polar structure as well as a bent shape.
• This is because oxygen is more electronegative than hydrogen, which means it attracts electrons better.
• Water is an excellent solvent.
• Structure of water molecule:

Ice is lighter than water

• One oxygen atom is joined with two hydrogen atoms to form a water molecule.
• The intermolecular interaction of the water molecules holds the water molecules together in a liquid form at room temperature.
• The water molecules in a liquid state are continually whizzing around in the container and being rearranged.
• The $\mathrm{H}-\mathrm{O}$ attraction, not the $\mathrm{O}-\mathrm{O}$ attraction, holds the water together as it freezes over into ice.
• Ice's lattice structure prevents water molecules from moving around.
• However, because the $\mathrm{H}-\mathrm{O}$ bond is not as tight as the $\mathrm{O}-\mathrm{O}$ bond, it expands somewhat after the $\mathrm{H}-\mathrm{O}$ bond takes over.
• As a result, water has a higher density than ice.