Final answer:
Ice forms a hydrogen-bonded, cagelike structure that is less dense than liquid water due to the permanent and orderly arrangement of water molecules. The solid-state of water's unique hexagonally-shaped framework allows ice to float on water, contrasting with the liquid's more disordered state.
Step-by-step explanation:
The water forms a hydrogen-bonded structure when it freezes into ice. In this arrangement, each water molecule accepts two hydrogen bonds from two other water molecules and donates two hydrogen atoms to form hydrogen bonds with two more water molecules, resulting in an open, cagelike structure. This structure is hexagonally shaped and less dense than the more disordered liquid water due to the permanent hydrogen bonding network. When water freezes, the systematic arrangement in a crystal structure is formed, which leads to ice being less dense than water. As the ice melts, it loses this structured arrangement, increases in entropy, and becomes more disordered because the hydrogen bonds are continually being broken and formed.
Additionally, the bent shape of the water molecules in ice creates gaps within this network, contributing to the unique property of ice being less dense than water, which allows it to float. Ice's crystal structure plays a crucial role in biological systems including the physical structures of proteins and nucleic acids due to the stable hydrogen bonds.