What does “Filling rules” actually mean in Structure of Atom, and why does it matter for NEET?
Aufbau (lowest energy first), Pauli (max two electrons, opposite spins) and Hund (singly fill before pairing).
In simple words: Aufbau (lowest energy first), Pauli (max two electrons, opposite spins) and Hund (singly fill before pairing). Getting Filling rules clear matters because NEET questions on Structure of Atom usually test this idea directly, not just a formula you memorised.
Key point
Filling rules
Common mistake
pairing electrons in a subshell before every orbital has one.
Memory tip
fill each orbital singly with parallel spins first, then pair up.
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