Question

If the nitrogen atom had an electronic configuration of $1s^7$ it would have lower energy than that of the normal ground state configuration $1s^2,2s^2,2p^3$ because the electrons would be closer to the nucleus. $1s^7$ is not observed because it violates:

• A. Heisenberg’s uncertainty principle
• B. Hund’s rule
• C. Pauli's exclusion principle
• D. Aufbau Principle

Answer 1

The correct option is C Pauli's exclusion principle

According to Heisenberg's uncertainity principle, the exact position and momentum of a fast moving particle cannot be calculated precisely at the same moment of time.

According to Aufbau Principle, the electrons are filled in various orbitals in the order of their increasing energies.

According to Hund's Rule, no electron pairing takes place in the orbitals in a sub - shell until each orbital is occupied by one electron with parallel spin.

According to Pauli's exclusion principle, two electrons in an atom cannot have the same set of all the four quantum numbers.

If configuration is written so with seven electrons in 1s orbital, many electrons would have same quantum numbers.Therefore, the given statement violates the Pauli's exclusion principle.