(GC1/12)Subatomic Particles & Basic Atomic Vocabulary

Key vocabulary for understanding isotopes, subatomic particles, and atomic charge concepts.

Isotope

Atoms of the same element with different numbers of neutrons.

Subatomic Particles

The three fundamental particles inside an atom: protons, neutrons, and electrons.

Proton

Positively charged particle (1.6 × 10⁻¹⁹ C) with a mass of 1 amu; defines the atomic number (Z).

Neutron

Neutral particle slightly heavier than a proton; varying its number creates isotopes.

Electron

Negatively charged particle (−1.6 × 10⁻¹⁹ C) with ~1⁄2000 the mass of a proton.

Atomic Number (Z)

The number of protons in an atom; identifies the element on the periodic table.

Mass Number (A)

The total number of protons plus neutrons in an atom.

amu (Atomic Mass Unit)

Standard unit of mass for subatomic

Ion

Atom or molecule with unequal numbers of protons and electrons, giving it a net charge.

Cation

Positively charged ion formed when an atom loses electrons.

Anion

Negatively charged ion formed when an atom gains electrons.

Charge of a Proton

+1 or +1e (1.6 × 10⁻¹⁹ coulombs).

Charge of an Electron

−1 or −1e (−1.6 × 10⁻¹⁹ coulombs).

Neutral Atom

Atom with equal numbers of protons and electrons, resulting in no net charge.

Valence Electrons

Outer-most electrons; higher potential energy and chiefly responsible for bonding interactions.