1. Matter - anything that has rest mass and volume and is made up of particles.
2. Atom - the basic unit of chemistry.
3. Element - a pure substance which is composed of a single type of atoms.
4. Compound - a pure chemical substance composed of more than one element.
5. Molecule - the smallest indivisible portion of a pure chemical substance.
6. Substance - a kind of matter with a definite composition and set of properties.
7. Phase - the fundamental state of matter.
8. Solid - characterized by structural rigidity and resistance to changes of shape or volume.
9. Liquid - a nearly incompressible fluid that conforms to the shape of its container.
10. Gas - gas particles are widely separated from one another.
11. Plasma - formed by heating a gas or subjecting it to strong electromagnetic fields.
12. Ion - an atom or a molecule, that has lost or gained one or more electrons.
13. Anion - an ion with more electrons than protons, giving it a net negative charge.
14. Cation - an ion with fewer electrons than protons, giving it a positive charge.
15. Reaction - when a chemical substance is transformed as a result of its interaction with another substance.
16. Bonding - atoms sticking together in molecules or crystals are said to be bonded.
17. pH Acidity and basicity - a numeric scale used to specify the acidity or basicity of an aqueous solution.
18. Redox - a chemical reaction in which the oxidation states of atoms are changed.