Question

why did he fill each orbital individually before pairing the electrons? open - ended question type your answer here

Explanation:

This follows Hund's rule. Electrons occupy degenerate (equal - energy) orbitals singly first with parallel spins to maximize the total spin multiplicity. This results in a lower - energy state for the atom as it minimizes electron - electron repulsion.

Answer:

This is due to Hund's rule, which states that electrons will occupy degenerate orbitals singly with parallel spins before pairing up to achieve a lower - energy, more stable electron configuration by minimizing electron - electron repulsion.