An atom is the basic unit of matter that makes up all substances around us. It is the smallest particle of an element that retains the chemical properties of that element.
An atom consists of three main subatomic particles:
- Protons – positively charged particles found in the nucleus (center) of the atom.
- Neutrons – neutral particles (no charge) also located in the nucleus, adding mass and stability.
- Electrons – negatively charged particles that move around the nucleus in regions called electron shells or orbitals.
The nucleus, containing protons and neutrons, is very small but holds almost all of the atom’s mass. Electrons are much lighter and occupy most of the atom’s space, giving atoms their size.
The number of protons in an atom is called the atomic number and determines which element the atom belongs to (for example, hydrogen has 1 proton, carbon has 6, oxygen has 8). Atoms can combine with each other through chemical bonds to form molecules and compounds, which make up all matter in the universe.
In short, an atom is like the building block or “Lego piece” of matter, from which everything physical is constructed.