PHYSICAL PROPERTIES

2. The rapid vaporization of a liquid that occurs when its vapour pressure equals the atmospheric pressure surrounding it.
4. The mass per unit volume of a substance; a unique property of water is that its solid form (ice) is less dense than its liquid form.
6. Another term for 'state,' referring to solid, liquid, or gas. A phase change occurs during melting, boiling, or freezing.
7. The process in which a liquid changes to a solid when heat is removed; for pure water, this occurs at 0°C at standard pressure.
11. The process in which a solid changes to a liquid when heat is added; for water, this occurs at 0°C.
13. The process where a liquid changes to a gas at temperatures below its boiling point, occurring only at the liquid's surface.
14. A measure of the average kinetic energy of the particles in a substance, measured in degrees Celsius (°C).
15. The capacity to do work or produce change; during boiling, heat energy is used to break intermolecular bonds, not raise the temperature.

1. The process where a gas or vapour changes into a liquid, such as when water droplets form on a cold surface.
3. A transparent, tasteless, odourless chemical substance (H₂O) that is essential for life and exhibits unique physical properties.
5. Relating to motion; during boiling, the kinetic energy of water molecules increases until they have enough energy to escape as vapour.
8. The increase in volume of a substance, often when heated. Water expands when it freezes, which is unusual.
9. The gaseous state of a substance (like water) that is normally liquid or solid at room temperature.
10. The distinct form in which matter can exist; for water, these are solid (ice), liquid (water), and gas (water vapour).
12. The form of energy that is transferred between systems or objects at different temperatures; required to change water's state.