Final answer:
Ice floats in liquid water because of a lattice structure held together by hydrogen bonds.
Step-by-step explanation:
The lattice structure of ice is held together by hydrogen bonds. Hydrogen bonding occurs when the positively charged hydrogen atom in a molecule is attracted to the negatively charged atom in another molecule. In the case of ice, 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, producing an open, cage-like structure.
These hydrogen bonds create a lattice structure that is less dense than the freely flowing molecules of liquid water. This lower density enables ice to float on water. In contrast, most other substances are denser in their solid state.
It's important to note that hydrogen bonding also plays a crucial role in biological structures, such as proteins and nucleic acids.