Atomic particle with one negative charge (1-)

Area around an atomic nucleus where an electron is most likely to be found.

Neutral particle in the nucleus of an atom.

Small area in the center of an atom in which most of an atom's mass and positive charge is concentrated.

Atomic particle with one positive charge (1+)

The number of protons in an atom of an element.

Atom that is no longer neutral because it has gained or lost electrons.

Any of two or more atoms of the same element that have different numbers of neutrons.

Sum of the number of protons and neutrons in an atom.

Area around an atomic nucleus where an electron is most likely to be found.

Process that occurs when an unstable atomic nucleus changes into another more stable nucleus by emitting radiation.

Describes elements that spontaneously emit radiation.

Occurring without external force or cause.