JAMB Chemistry 2024 Paper

Concept:The configuration of nitrogen shows the application of Hund's rule in filling equal-energy orbitals.Explanation:Nitrogen has 7 electrons.Its electrons fill in this order: $1s^2$, then $2s^2$.The remaining 3 electrons enter the three 2p orbitals: $2p_x$, $2p_y$, and $2p_z$.Hund's rule states that electrons occupy degenerate orbitals singly with parallel spins before pairing.So one electron goes into each $2p$ orbital: $2p_x^1\, 2p_y^1\, 2p_z^1$.This is the stable ground-state configuration of nitrogen.It is not an excited state, nor is it undergoing energy changes or instability.Answer:D. The atom is simply obeying rules governing electron configuration.