How solid changes to liquid?

Answer 1

melting
SOLID ============> LIQUID
to answer this question let us take ice as an example.

Ice begins as water which is two parts hydrogen and one part oxygen. Unlike other similar substances though water is a liquid at room temperature while the other similar substances are gases at room temperature which makes water a very interesting subject. Water is a liquid at room temperature because the hydrogen atoms are attracted to the oxygen atoms that make up water. Because of this the hydrogen atoms "connect" to the oxygen atoms. This is called a hydrogen bond. This keeps the water from becoming a gas at room temperature. When the water is put on the stove to boil though we see "steam" coming from the pan we put it in. This is the gas form of water. Water becomes a gas when put over high temperature because the heat is giving the molecules more energy to move around causing the hydrogen bond to break making the liquid a gas.

If this is the case with the liquid form of water becoming a gas it is the exact opposite of it becoming a solid. Water turns into a solid when put in freezing temperature. It becomes a solid because the molecules are slowing done and soon they get so slow they hardly move at all. If kept in the freezing temperature then it will stay a solid. But when taken out slowly the molecules will start to get warm again causing the solid to become a liquid because the molecules are moving again and are connecting together to make the hydrogen bond I spoke of earlier. I hope that has answered your question.