Skip to content
CHEM 121 Studioby Learn4Less · UBC CHEM 121

CHEM 121 glossary

Ground state

The lowest-energy state of an atom, molecule or particle. Every other state is an excited state; an atom left alone falls back to its ground state by emitting photons.

Energy levels of the hydrogen atomn = 1: −2.18 × 10⁻¹⁸ J; n = 2: −5.45 × 10⁻¹⁹ J; n = 3: −2.42 × 10⁻¹⁹ J; n = 4: −1.36 × 10⁻¹⁹ J.n = ∞0 Jn = 1−2.18 × 10⁻¹⁸ Jn = 2−5.45 × 10⁻¹⁹ Jn = 3−2.42 × 10⁻¹⁹ Jn = 4−1.36 × 10⁻¹⁹ J

Hydrogen's ground state is n=1n = 1, the lowest level.

Example

Hydrogen's ground state is n=1n = 1 at −2.179×10−18-2.179\times10^{-18} J. For a particle in a box it is n=1n = 1 with E1=h2/8mL2>0E_1 = h^2/8mL^2 > 0, never zero.

See alsoExcited stateEnergy levelZero-point energy