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CHEM 121 Studioby Learn4Less · UBC CHEM 121

CHEM 121 glossary

Principal quantum number

The quantum number n=1,2,3,…n = 1, 2, 3, \ldots that labels the shell. It sets the orbital's size and, in a one-electron species, its energy alone: En=−Z2RH/n2E_n = -Z^2R_H/n^2.

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 = 5: −8.72 × 10⁻²⁰ 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 Jn = 5−8.72 × 10⁻²⁰ J

In hydrogen the energy depends only on nn.

Example

n=3n = 3 gives a shell of 3 subshells (3s, 3p, 3d), 9 orbitals and up to 18 electrons; in hydrogen its energy is −2.179×10−18/9=−2.42×10−19-2.179\times10^{-18}/9 = -2.42\times10^{-19} J.

See alsoShellQuantum numbersEnergy level