* The state of matter of water can be solid (ice), liquid (water), or gas (steam).
* Changing the state of matter of a substance requires adding or removing energy.
* Scientists study the properties of matter in different states of matter, such as solids, liquids, and gases.
* The state of matter of a substance can affect its ability to conduct heat and electricity.
* Plasma, often called the fourth state of matter, is a hot, ionized gas that is found in stars and lightning.