Wikijunior:The Elements/Matter Is The Stuff Around You
What is Matter?
Matter is everything around you. Matter is everything made of atoms and molecules. Matter is anything that has a mass and occupies space, which means it can be weighed. However, some things that are matter can't be scooped up and weighed. For instance, matter is also related to light.
Even though matter can be found all over the universe, you usually find it in just a few forms. As of 1995, scientists have identified five states of matter. They may discover one more by the time you get old.
You should know about solids, liquids, and gases, because they are the states of matter you deal with every day. Ionized gases, or plasmas, are also a state of matter. In 1995 scientists first created a new state of matter called a Bose-Einstein condensate. The scientists who first made Bose-Einstein condensates received a Nobel Prize for their work in 2001.
But what makes a state of matter? It's all about what the smallest parts of matter, called molecules and atoms, are doing. They might be flying around really fast, like in a gas. Or they might be stuck together in a rigid form to make a solid. These are very different ways for molecules to behave, and they lead to very different properties, as we shall see later.
Elements and compounds can move from one state to another and not change. Nitrogen as a gas still has the same properties as liquid nitrogen. The liquid state is denser but the molecules are still the same. Water is another example. The compound water is made up of two hydrogen atoms and one oxygen atom. It has the same molecular structure whether it is a gas, liquid, or solid. Although its physical state may change, its chemical state remains the same.
So, you ask "What is a chemical state?" If the formula of water were to change, that would be a chemical change. If you added another oxygen atom, you would make hydrogen peroxide, a different molecule. Changing states of matter is about changing densities, pressures, and temperatures. If the basic chemical structure changes, that is a chemical change.