1. Increased Kinetic Energy: The particles must absorb enough energy to increase their kinetic energy, causing them to move faster and further apart. This energy can be supplied by heat.
2. Overcoming Intermolecular Forces: The particles need to overcome the attractive forces (e.g., hydrogen bonding, dipole-dipole interactions, London dispersion forces) holding them together in the liquid state.
3. Vapor Pressure Equal to Atmospheric Pressure: When the vapor pressure of the liquid (the pressure exerted by the escaping vapor molecules) becomes equal to the atmospheric pressure, the liquid boils. At this point, the liquid can turn into a gas freely.
In simpler terms:
* Heat is added: This makes the liquid's particles move faster and try to escape from the liquid's surface.
* Particles break free: When enough particles have enough energy, they overcome the forces holding them together and escape into the gas phase.
* Boiling point: The temperature at which this happens is the boiling point of the liquid.
Think of it like this: Imagine you're holding a bunch of marbles together with a strong magnet. If you shake the container hard enough, the marbles will overcome the magnet's force and fly out. In the same way, heat makes liquid particles vibrate so strongly they break free and become gas.
