Changes of State

When a substance changes state there is no change in temperature.

When a solid is heated energy is transferred to the particles making them vibrate more which means the temperature increases. The potential energy of the solid remains constant but the kinetic energy increases.

At melting point the particles do not vibrate any faster, meaning the kinetic energy and temperature are constant. The bonds that keep the particles in a rigid shape are broken and the potential energy increases.

In liquid form the particles are still in contact with each other but can slide past each other. As more energy is transferred the particles vibrate more. The kinetic energy increases but the potential energy is constant.

At boiling point the particles do not vibrate any faster, meaning the kinetic energy and temperature are constant. The bonds holding the particles together are all broken, this takes much more energy than when melting since all the bonds need to be broken.

When a gas is heated the particles move faster, meaning the kinetic energy and temperature increases. The potential energy stays constant.