For which of the following element, all of its existing ion, M^x+, will be diamagnetic? — Atomic Structure Chemistry Question

💡 Solution & Explanation

Sodium (Na) is an alkali metal that forms only one stable ion under ordinary chemical conditions: Na^+. The sodium ion has a completely closed-shell electronic configuration equivalent to neon ([Ne] 1s^2 2s^2 2p^6), which contains zero unpaired electrons. Thus, all of its existing ions are completely diamagnetic. In contrast, copper (Cu^2+), iron (Fe^2+, Fe^3+), and chromium (Cr^2+, Cr^3+) form ions with partially filled d-subshells, which are paramagnetic.