Correct set of quantum numbers defining the highest energy electron in scandium (I) ion is — Atomic Structure Chemistry Question

💡 Solution & Explanation

The neutral scandium atom (Sc, Z = 21) has the ground-state electronic configuration of [Ar] 3d^1 4s^2. When forming the scandium (I) ion (Sc^+), the outermost valence electron is removed first from the 4s subshell, resulting in the electronic configuration: Sc^+ = [Ar] 3d^1 4s^1. In transition metals, although the 3d level is energetically close, the highest energy orbital occupied by a valence electron is the outermost 4s subshell. For this 4s valence electron, the quantum numbers are n = 4, l = 0, m = 0, and s = +1/2 (option c).