Matter

Definition

Matter is anything that has mass and occupies space. It is composed of atoms, which are the fundamental units of chemical elements.

5 Must Know Facts For Your Next Test

1. All matter is composed of atoms, which can combine to form molecules.
2. Atoms consist of protons, neutrons, and electrons.
3. Isotopes are variants of a particular chemical element that differ in neutron number.
4. Ions are atoms or molecules that have gained or lost one or more electrons, giving them a net charge.
5. Molecules are two or more atoms bonded together and can be elements or compounds.

Review Questions

• What are the three main components of an atom?
• How do isotopes of an element differ from each other?
• What happens to an atom when it becomes an ion?

Related terms

Atom: The smallest unit of a chemical element, consisting of a nucleus surrounded by electrons.

Isotope: Variants of a particular chemical element that have different numbers of neutrons but the same number of protons.

Molecule: A group of two or more atoms bonded together, representing the smallest fundamental unit of a chemical compound.