When water [tex]\(\left( \text{H}_2\text{O} \right)\)[/tex] freezes into ice, several properties of the [tex]\(\text{H}_2\text{O}\)[/tex] molecules undergo changes. For instance:
1. Energy of the [tex]\(\text{H}_2\text{O}\)[/tex]: During the freezing process, thermal energy is removed, causing the water molecules to lose kinetic energy. This results in a more ordered state (ice), so the energy state of the molecules changes.
2. Arrangement of the [tex]\(\text{H}_2\text{O}\)[/tex]: In liquid water, [tex]\(\text{H}_2\text{O}\)[/tex] molecules are arranged more randomly and are free to move past each other. When water freezes, the [tex]\(\text{H}_2\text{O}\)[/tex] molecules arrange themselves into a rigid, hexagonal lattice structure, resulting in ice. Hence, the arrangement of the molecules changes significantly.
3. Properties of the [tex]\(\text{H}_2\text{O}\)[/tex]: Physical properties such as density and volume change when water freezes. For example, water expands and becomes less dense upon freezing.
However, one key aspect remains unchanged:
Identity of the [tex]\(\text{H}_2\text{O}\)[/tex]: Despite the changes in energy, arrangement, and physical properties, the fundamental chemical composition of the molecules remains identical. Each molecule remains composed of two hydrogen atoms and one oxygen atom ([tex]\(\text{H}_2\text{O}\)[/tex]).
Therefore, the property that stays the same when water freezes into ice is the identity of the [tex]\(\text{H}_2\text{O}\)[/tex].
