Question

the image below shows an orbital diagram for magnesium. which rule for filling orbital diagrams is violated in this diagram? a) paul exclusion principle b) heisenberg uncertainty principle c) aufbau principle d) hunds rule

Explanation:

• Paul exclusion principle: States that no two electrons in an atom can have the same set of four quantum numbers. Each orbital can hold a maximum of 2 electrons with opposite spins. In the given diagram, this is not violated as each orbital with two electrons has opposite - spin arrows.
• Heisenberg uncertainty principle: Deals with the inability to simultaneously know the exact position and momentum of a particle. It is not relevant to orbital - filling rules.
• Aufbau principle: Electrons fill the lowest - energy orbitals first. The order of filling (1s, 2s, 2p, 3s) is followed in the diagram, so this principle is not violated.
• Hund's rule: Electrons occupy degenerate orbitals (same - energy orbitals) singly before pairing up. In the 2p sub - level (which has 3 degenerate orbitals), electrons should first fill each 2p orbital with one electron (all with the same spin) before pairing. But in the given diagram, electrons are paired in the 2p orbitals before all 2p orbitals have at least one unpaired electron.

Answer:

D. Hund's rule