Electronic Configuration — Prelims Strategy

Prelims Strategy

To excel in NEET questions on electronic configuration, a systematic approach is vital. Firstly, thoroughly memorize the Aufbau principle's filling order ($1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s$).

Practice writing configurations for elements up to Z=57 and beyond, including those with f-block filling. Secondly, internalize Pauli's exclusion principle (max 2 electrons per orbital, opposite spins) and Hund's rule (single occupancy with parallel spins for degenerate orbitals first).

For numerical problems involving quantum numbers, remember the rules: $l \le n-1$ and $-l \le m_l \le +l$. Be particularly careful with exceptions like Cr and Cu, and the order of electron removal for cations (highest 'n' first, e.

g., $4s$ before $3d$ for transition metals). When solving MCQs, eliminate options by checking for violations of any of these rules. For Group 2 elements, always look for the $ns^2$ valence configuration.

Trap options often involve misapplying filling rules, confusing valence electrons with unpaired electrons, or incorrect noble gas core notation. Practice with a wide variety of questions, including those that link configuration to periodic properties like ionization energy.