Question

Distribution of electrons in various orbitals is known as electronic configuration. The electrons filled in orbitals must obey the following rules:

I. Aufbau principle II. Pauli exclusion principle III. Hund's rule of maximum multiplicity

Consider the following orbital diagram and choose which of the following rules among these is/are violated?

• A. Only rule I is violated.
• B. Only rule II is violated.
• C. Only rule III is violated.
• D. Both rules I and III are violated.

Answer 1

Answer: (C)

Only rule III (Hund's rule) is violated.

Answer 2

For electrons in equivalent (degenerate) orbitals, Hund’s rule requires all electrons to have the same spin (preferably all ↑) until each orbital contains one electron. In the 2p subshell given, two electrons show ↑ while one shows ↓, breaking Hund’s rule. The Aufbau principle and Pauli exclusion principle are followed.