When a solid is heated, the particles gain energy and vibrate faster and faster until the attractive forces between them fails to hold them together at their fixed positions. The particles then break away in small groups and move faster and further apart. The solid has changed into a liquid. This change in the arrangement and motions of particles is called melting. For pure substance, melting only occurs at fixed temperature known as melting points. When a liquid is cooled, the particles slow down. The attractive forces between these particles become stronger and stronger.
When the attraction forces become so strong that they draw back the particles their fixed positions, the substance becomes solid. This change in the arrangement and motion is known as freezing.When the small groups of particles are broken up into single particles and the attraction forces between the particles become negligible, the liquid changes and had turned into gas. This change in the arrangement is known as boiling. When a liquid is cooled, the particles slow down.
When the attraction forces become so strong that they draw back the particles their fixed positions, the substance becomes solid. This change in the arrangement and motion is known as freezing.When the small groups of particles are broken up into single particles and the attraction forces between the particles become negligible, the liquid changes and had turned into gas. This change in the arrangement is known as boiling. When a liquid is cooled, the particles slow down.