Subatomic particles

Science

Definition

The particles that make up an atom: protons (positive charge, in the nucleus), neutrons (no charge, in the nucleus), and electrons (negative charge, orbiting the nucleus). The number of protons defines the element, while changes in neutrons or electrons create isotopes or ions.

Examples

  • A carbon-12 atom has 6 protons, 6 neutrons, and 6 electrons
  • Removing an electron from sodium creates a Na⁺ ion with a positive charge
  • Carbon-14 has 2 extra neutrons compared to carbon-12, making it radioactive and useful for dating
Key Fact

Proton mass ≈ neutron mass ≈ 1 amu; electron mass ≈ 1/1836 amu. Atomic number = number of protons.

Related Terms

Atomic models Electron configuration Nuclear physics Quantum basics

Study This Concept

Practice subatomic particles with free review games in these units:

Chemistry Unit 1: Matter and Atomic Structure