Electrons in the Atom Key Terms

Photon

The quantum of electromagnetic energy, regarded as a discrete particle having zero mass, no electric charge, and an indefinitely long lifetime.

Spectroscopy

Study of spectra, especially experimental observation of optical spectra.

Subatomic –

any smaller part of an atom such as protons, neutrons, and electrons

Orbital Notation

– a way to show the location of the electrons in the atom

Quantum number

A set of real numbers assigned to a physical system that individually characterize the properties and collectively specify the state of a particle or of the system.

Orbital

The wave function of an electron in an atom or molecule, indicating the electron's probable location.

Sublevel

One or more orbitals in the electron shell of an atom.

Hund's Rule

If two or more orbitals of equal energy are available, electrons will occupy them singly before filling them in pairs.

Pauli Exclusion Principle

No two electrons may simultaneously occupy the same quantum state.

Aufbau Principle

Used to determine the electron configuration of an atom, molecule, or ion. The principle postulates a hypothetical process in which an atom is "built up" by progressively adding electrons. As they are added, electrons are added to the lowest energy orbitals first (e.g. 1s before 2s).