Here's the explanation:
* Water molecules are polar: The oxygen atom in a water molecule has a slightly negative charge, while the hydrogen atoms have slightly positive charges. This polarity allows water molecules to form hydrogen bonds with each other.
* Hydrogen bonds in liquid water: In liquid water, these bonds are constantly forming and breaking, allowing the molecules to move freely and pack relatively close together.
* Hydrogen bonds in ice: When water freezes, the hydrogen bonds become more stable and hold the molecules in a fixed, crystalline structure. This structure is characterized by an open, hexagonal lattice with large empty spaces between the molecules.
* Lower density: Because of these large spaces, ice has a lower density than liquid water. This is why ice floats!
In summary, the open, crystalline structure of ice, resulting from the stable hydrogen bonds between water molecules, leads to its lower density compared to liquid water.
