Question

a student draws the orbital diagram below for the 3d electrons in a v atom.
what, if anything, is incorrect about the drawing?

answer
a it violates the aufbau principle.
b it violates the pauli exclusion principle.
c it violates the heisenberg uncertainty principle.
d it violates hunds rule.
e there is nothing incorrect about the drawing.

Explanation:

• Aufbau principle: Electrons fill orbitals from the lowest - energy to the highest - energy. This diagram does not violate this principle as it is about the 3d orbital (assuming proper filling order before).
• Pauli exclusion principle: No two electrons in an atom can have the same set of four quantum numbers. Each box (orbital) in the diagram has at most two electrons with opposite spins, so it does not violate this principle.
• Heisenberg uncertainty principle: Deals with the inability to simultaneously know the exact position and momentum of a particle. This is not related to the orbital - filling pattern shown.
• Hund's rule: Electrons will fill degenerate orbitals (orbitals of the same energy) singly first with parallel spins before pairing up. In the given 3d orbital diagram, electrons are paired up in the first orbital before filling the other 3d orbitals singly. This violates Hund's rule.

Answer:

D. It violates Hund's rule.