Beryllium (Be) — its atomic orbitalsBeryllium is element 4: period 2, group 2, alkaline earth of the s block. Its ground-state configuration is 1s² 2s², so its outermost occupied shell is n = 2 and holds 2 electrons.Each orbital below is the hydrogen-like solution at the effective nuclear charge Slater's rules give its subshell, so its radial nodes and its angular nodes fall where the wavefunction changes sign rather than where a drawing puts them. Slater screening gives the effective charge; the energy is the hydrogen-like −13.606 Z_eff²/n², and ⟨r⟩ the mean radius of one orbital of the subshell.

Subshell

Electrons

Z_eff

Energy (eV)

Radial nodes

Angular nodes

⟨r⟩ (Å)

3.70

-186.26

0.215

1.95

-12.93

1.628

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