The fundamental units of matter are called atoms.
Atoms are the basic building blocks of ordinary matter. Everything around us is made up of atoms, which consist of a nucleus containing protons and neutrons, surrounded by electrons that orbit the nucleus. Each element on the periodic table is defined by its type of atom, characterized by the number of protons in its nucleus (its atomic number).
Atoms can combine to form molecules, which in turn compose compounds and materials. Understanding atoms is crucial for studying chemistry, physics, and biology, as they play a fundamental role in the structure and behavior of all matter.