Chapter 8, Problem 8.87QE

Interpretation Introduction

Interpretation:

The electron configuration for the $2+$ cation of calcium has to be determined.

Concept Introduction:

The electronic configuration is defined as the distribution of electrons in various atomic orbitals of the atom. The electrons that are present in an outermost orbital are known as valence electrons whereas those present in the orbitals with lower quantum numbers are called core electrons. The general outer electronic configuration of $s\text{block}$ elements is $n{s}^{1-2}$, that of $p\text{block}$ elements is $n{s}^{2}n{p}^{1-6}$, that of $d-\text{block}$ elements is $\left(n-1\right)d^{1-10}n{s}^{0-2}$ and that of $f\text{block}$ elements is $\left(n-2\right)f^{1-14}\left(n-1\right)d^{0-10}n{s}^2$.

Electrons are filled in orbitals in accordance with three rules: Aufbau principle, Hund’s rule, and Pauli’s exclusion principle. Aufbau principle states that electrons are filled in the orbitals from lower to higher energy level as follows:

  $1s<2s<2p<3s<3p<4s<3d<4p<5s<4d<5p<6s<4f<5d<6p<7s$

Hund’s rule states that initially each orbital is singly occupied and then pairing occurs and Pauli’s exclusion principle states that the spin of two electrons in one orbital is always different.