Final answer:
Boiling is a phase change from liquid to gas occurring at a substance's boiling point, where absorbed energy overcomes intermolecular forces without increasing temperature.
Step-by-step explanation:
The process of boiling is a phase change where a liquid becomes a gas. At the molecular level, when water reaches its boiling point of 100° C, energy is absorbed and used to overcome intermolecular forces holding the molecules together in the liquid phase.
The temperature remains constant during this process, as the energy is used for the phase transition rather than increasing the kinetic energy of the molecules. As more energy is introduced, water molecules move faster, completely overcoming the attractive forces and allowing them to escape as a gas. The change from liquid to gas occurs at the boiling point, which is a distinct physical property of the substance.