Question

Which of the following rules have been violated while writing the following electronic configuration of oxygen atom?
$$\begin{array}{c}\upharpoonleft \downharpoonright \end{array}\begin{array}{c}\upharpoonleft \downharpoonright \end{array}\begin{array}{ccc}\upharpoonleft \downharpoonright & \upharpoonleft \upharpoonleft & \end{array}$$

• A. Aufbau principle
• B. Hund’s rule
• C. Pauli’s exclusion principle
• D. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Heisenberg's Uncertainty principle

Answer 1

Answer: (B), (C)

The correct options are
B Hund’s rule
C Pauli’s exclusion principle

Aufbau principle states that electrons are filled into atomic orbitals in the increasing order of orbital energy levels.

Hund's rule states that every orbital in a subshell is singly occupied before pairing of electrons occurs. Also, all of the electrons in singly occupied orbitals have the same spin. Here this rule is not applied, in p-orbital pairing is already done before filling all the orbitals in p subshell.

According to Pauli's exclusion principle, no two electrons can have same set of four quantum numbers.
This means, only two electrons can exist in the same orbital and they will have opposite spin.

Hence, while writing this electronic configuration, Hund's rule and Pauli's exclusion principle is violated.