This chapter was about solid, liquid, and gas which are the 3 states of matter. Matter can change from oe state to another. Melting is when a solid changes to a liquid. Freezing is when a liquid changes to a solid. Evaporation and boiling changes liquid to a gas. Condensation is when a gas changes to a liquid. It was also about solutions. In a solution you have a solvent which is a substance that dissolves other materials. A solute isthe substance that is dissolved. Solutions don't have to be liquid. The air we breathe and also lots of solids are really solutions. Another thing we learned was about chemical reactions and energy in chemical reactions. An exothermic reaction is a chemical reaction in which more energy is given off than taken in. An example of this is burning wood. An endothermic reaction is a reaction in which more energy is taken in than given off. An example of this is using an ice pack.