It is called "melting". It means that when a solid gets so hot, by the increase in Kinetic Energy that it contains, the atoms move around so much that the state of matter changes to a liquid, that is to say it undergoes a change of state. Further heating will change the liquid to a gas - another change of state.
These are changes of phase and physical phenomenons:
- solid to liquid: melting
- gas to liquid: liquefaction (or condensation)
gas to a liquid
condensation. example: clouds forming
When a solid changes to a liquid, it does so by the process of melting.
This change in the state of matter (liquid to solid) is called freezing; it is a physical change, the chemical nature of the molecules is not changed.
It is a 'State' Change called Liquification, precipitation and other terms depending on the process that caused the state change.
gas to a liquid
condensation
If we take solid, liquid and gas being the three main states of matter (plasma being an arguable fourth), then from solid to liquid, the process melting occurs, from liquid to gas evaporation or boiling (they are different things) occur. Then from gas to liquid condensation occurs and from liquid to solid freezing occurs.
when matter changes state either evolution or absorption of enrgy occurs for example when a solid changes to liquid or a liquid changes to gas energy is absorbed and in case of conversion of gas to liquid or liquid to solid enrgy is liberated....
You are adding heat/energy. It is melting.
condensation. example: clouds forming
Boiling, the term for that is boiling point.
As matter changes from solid to liquid (in other words when solid matter melts) the temperature remains constant. After all the solid has melted, the temperature of the matter may begin to rise again if the environment is warmer than the melting point of the solid.
This is called evaporation.
It occurs when a gas changes into a liquid. Heat is given off.
When gas cools and changes into liquid, it undergoes a process called condensation. This occurs when the temperature of the gas decreases, causing its particles to lose energy and come closer together, eventually forming liquid droplets.
Vaporization is the process in which a substance changes from a liquid or solid state into a gas or vapor. This usually occurs when the substance is heated to its boiling point.