Question

Filling of electrons in degenerate orbitals are governed by:

• A. Hund's rule
• B. Planck's Law
• C. De Broglie's wave-particle duality
• D. Photoelectric effect

Hint:

When applying Hund’s rule, remember that the electrons will try to occupy different sub-orbitals within a particular orbital, before pairing, as that minimizes repulsive forces. The spins will also remain parallel until pairing, as this configuration increases the overall stability of the atom.

Answer 1

The Correct Option is A

Degenerate orbitals are atomic orbitals that have the same energy level. These are usually p, d, and f subshells. Hund’s rule describes the way electrons are filled into these orbitals. This rule states that:
• Electrons will individually occupy each orbital within a subshell before doubling up in any one orbital.
• Electrons in singly occupied orbitals will all have the same spin (either all spin-up or all spin-down).
This rule is a direct consequence of the repulsive forces between electrons, as electrons will try to maximize the distance between them, and occupy different orbitals before pairing in the same orbital. This results in the maximum possible number of unpaired electrons with parallel spins for a system.
The other options are not relevant to electron filling in atomic orbitals:
• Planck’s Law relates the energy of a photon to its frequency.
• de-Broglie’s wave-particle duality describes the dual nature of matter, that it has both wavelike and particle like properties.
• Photoelectric effect describes the ejection of electrons when light is incident on a material.