Question

"No two electrons in an atom can have the same set of four quantum numbers". This is known as

• A. Pauli's Principle
• B. Hund's Rule
• C. Aufbau Principle
• D. Lewis Rule

Hint:

Think of the Pauli Exclusion Principle as the "No Clones" rule for electrons. Every electron in an atom must have its own unique "ID card" comprised of its four quantum numbers.

Answer 1

The Correct Option is A

1. Pauli's Exclusion Principle: States that no two electrons in the same atom can have identical values for all four quantum numbers ($n, l, m_l, m_s$). This implies that if two electrons occupy the same orbital (having the same $n, l,$ and $m_l$), they must have opposite spins ($m_s = +1/2$ and $-1/2$).

2. Distinction from other rules:

• Aufbau Principle: Electrons fill lower-energy orbitals first before moving to higher-energy ones.

• Hund's Rule: Orbitals of the same energy (degenerate orbitals) are each occupied by one electron before any orbital is doubly occupied.
Consequently, Pauli's Principle is the rule that limits each orbital to a maximum of two electrons with opposite spins.