Matter: everything that has mass and volume and is composed of particles, whether pure substances or mixtures.
Atom: the basic, smallest unit of matter chemistry considers. Atoms have weight, volume, and electric charge. They are made up of an atomic nucleus surrounded by a set of electrons revolving around it.
Subatomic particles: the particles that make up atoms and give them properties. There are three types: protons (positively charged), electrons (negatively charged), and neutrons (uncharged).
Molecules: the union of two or more atoms with unique properties, which form compounds.
Chemical element: a substance made up of a set of atoms that have the same number of protons in their nucleus. There are 118 chemical elements in the periodic table.
Chemical compounds: substances consisting of more than one chemical element in the periodic table. Their main characteristic is that they have a chemical formula, such as water, for example, which is composed of hydrogen and oxygen.