Chapter 2, Problem 2.92CP

Interpretation Introduction

Interpretation:

Anomalous electron configurations for the given element should be explained.

Concept Introduction:

Electronic configuration:

The electron configuration is the distribution of electrons of an atom or molecule in atomic or molecular orbitals.

1. (1) Electrons occupy in the lowest energy orbitals. The increasing order of orbital energy is $\text{s, p, d and f}$. The lowest energy orbital is $\text{1s}$. The order of energy of the orbital for the for the first three period is given below,

   $\text{1s, 2s, 2p, 3s,}\text{and 3p}$.

2. (2) The orbital which is closer to the nucleus has lower energy, therefore the 2s is lower in energy than 3s. Accordingly $2s$ is lower in energy than $\text{2p and 4s}$ is lower in energy than $\text{3d}$.
3. (3) In general, the orbitals can hold maximum of two electrons, the two electrons must have opposite spin.

The subshell ordering by Aufbau principle is given below, $\text{1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p, 8s, }\mathrm{...}$

s-Block element:

It is called as main group elements that result from the filling of an s orbital.

p-Block element:

It is also called as main group elements that result from the filling of an p orbital.

d-Block element:

It is called as transition metal elements that result from the filling of an p orbital.

f-Block element:

It is called as inner transition metal element that results from the filling of an p orbital.

Aufbau principle:

Aufbau principle states that in the ground state of an atom, electrons fill atomic orbitals of the lowest available energy levels before occupying higher levels.  For example, the 1s shell is filled before the 2s subshell is occupied.

The subshell ordering by this rule is

$\text{1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p, 8s, }\mathrm{...}$