Chapter AS, Problem 17PQ

Interpretation Introduction

Interpretation:

The valence electron configuration for the electrons in period 5 and group $3\text{A}$ has to be determined.

Concept Introduction:

To write electronic configuration certain rules have to be followed such as Hund rule, Pauli Exclusion principle and Aufbau rule.

If $Z$ is the atomic number then the electrons that are filled into the orbitals are $Z$. Electrons are generally filled in order of increasing energy. In an atom, 2 electrons can never have same group of 4 quantum numbers and this is Pauli Exclusion Principle.

When orbitals are degenerate then each orbital is first filled with 1 electron each before the second electron enters an orbital and this is Hund’s rules.