Question

part a
what is hunds rule?

• when filling orbitals of equal energy, electrons fill them singly first, with parallel spins.
• the chemical properties of elements are largely determined by the number of valence electrons they contain.
• the maximum number of electrons in an orbital is two.
• the maximum number of electrons in an orbital is eight.

Explanation:

Hund's rule specifically states that when filling orbitals of equal energy (degenerate orbitals), electrons occupy them singly first, each with the same (parallel) spin, before pairing up. The other options: the second is about valence electrons and chemical properties (not Hund's rule), the third is the Pauli exclusion principle (max 2 electrons per orbital), and the fourth is incorrect (max 8 in a shell, not orbital).

Answer:

A. When filling orbitals of equal energy, electrons fill them singly first, with parallel spins.