5.7 understand the changes that occur when a solid melts to form a liquid, and when a liquid evaporates or boils to form a gas

5.7 understand the changes that occur when a solid melts to form a liquid, and when a liquid evaporates or boils to form a gas

When a solid is heated, the molecules starts vibrating. At a time they lose their attraction force and move slowly. This time they reach the state liquid i.e. solid has melted. When more heat is given, the molecules totally lose their attraction force and move randomly. They have reached the state gas i.e. liquid has boiled.