Matching Pairs Phase changeOnline version match the picture of the phase change with the definition. by Amber Guy 1 2 3 4 This change happens when you decrease heat. This change takes place when the substances temperature gets lower than it's melting point and changes from a liquid to a solid. This change happens when you increase heat. This change takes place when a substance reaches it boiling point and change from a liquid to a gas This change happens when you decrease heat. This change takes place when a substance's temperature gets lower then it's boiling point and changes from a gas to a liquid. This change happens when you increase heat. This change takes place when you reach the melting point of the substance and changes from a solid to a liquid.