Electronic Configuration — Prelims Strategy

Prelims Strategy

For NEET prelims, mastering electronic configuration requires a systematic approach. Firstly, memorize the Aufbau filling order ($1s, 2s, 2p, 3s, 3p, 4s, 3d, dots$) and the $(n+l)$ rule for tie-breaking.

Secondly, thoroughly understand and apply Pauli's exclusion principle and Hund's rule of maximum multiplicity, especially for drawing orbital diagrams and determining unpaired electrons. Pay special attention to the exceptions for Chromium (Cr) and Copper (Cu) and their respective groups, as these are frequent traps.

When dealing with ions, remember to remove electrons from the outermost shell (highest 'n' value) first for cations, and add to the lowest available energy orbital for anions. Practice writing configurations for elements up to Z=36 and common transition metal ions.

For quantum number questions, systematically check each number against its allowed range. Numerical problems often involve counting unpaired electrons or identifying specific configurations. Avoid common mistakes like filling $3d$ before $4s$ for neutral atoms, or removing $3d$ electrons before $4s$ electrons for transition metal cations.