Which of the following is paramagnetic? — Atomic Structure Chemistry Question

💡 Solution & Explanation

A chemical species is paramagnetic if it possesses at least one unpaired electron. Let's analyze the species: (a) Zn^2+ = [Ar] 3d^10: completely filled d-subshell, so n = 0 (diamagnetic). (b) Ni^2+ = [Ar] 3d^8: 2 unpaired electrons, so n = 2 (paramagnetic). (c) Sc^3+ = [Ar] 3d^0: completely empty d-subshell, so n = 0 (diamagnetic). (d) O^2- = 1s^2 2s^2 2p^6: completely filled p-subshell, so n = 0 (diamagnetic). Thus, Ni^2+ is the only paramagnetic species.