What Are the 3 Subatomic Particles of an Atom? Quick Guide
The three subatomic particles of an atom are protons, neutrons, and electrons. Protons carry a positive charge and are found in the atom’s nucleus. Neutrons have no charge and also reside in the nucleus. Electrons are negatively charged and orbit the nucleus in shells.
How They Work Together
Protons and neutrons make up the nucleus and account for nearly all of an atom’s mass. A proton has a relative mass of 1 atomic mass unit (amu) and a charge of +1. A neutron has the same mass, roughly 1 amu, but no charge. Electrons are much lighter — about 1/1836 of an amu — and their negative charge balances the proton’s positive charge, keeping the atom neutral.
The number of protons defines the element. For example, a carbon atom always has 6 protons. Most carbon atoms also have 6 neutrons, giving a mass number of 12. The 6 electrons orbit the nucleus in two shells. This arrangement means the atom is electrically neutral and stable under normal conditions.
If an atom gains or loses electrons, it becomes an ion. A sodium atom (11 protons) that loses one electron becomes a Na⁺ ion with a net +1 charge. A chlorine atom (17 protons) that gains one electron becomes a Cl⁻ ion. These charged particles bond to form compounds like table salt (NaCl).
Key Takeaways
- The three subatomic particles are protons (positive charge, in nucleus), neutrons (no charge, in nucleus), and electrons (negative charge, orbiting the nucleus).
- Protons and neutrons have roughly equal mass (about 1 amu each), while an electron is about 1/1836 as massive.
- The number of protons determines the element; changing the number of neutrons creates isotopes International Union of Pure and Applied Chemistry.
- In a neutral atom, the number of electrons equals the number of protons.
