Chapter 7, Problem 7.82QP

Interpretation Introduction

Interpretation:

The number of unpaired electrons are present in given atoms have to be identified.

Concept introduction:

An orbital is an area of space in which electrons are orderly filled.  The maximum capacity in any type of orbital is two electrons.  An atomic orbital is defined as the region of space in which the probability of finding the electrons is highest.  It is subdivided into four orbitals such as $s,p,dandf$ orbitals which depend upon the number of electrons present in the nucleus of a particular atom.

Aufbau principle:

• Electrons first occupy orbitals with lower energy than higher energy.
• An orbital can be occupied only by two electrons having opposite spins.
• Each electron fills each orbital till it is half filled.  Greater the number of parallel spins of electrons more stable the orbital.  This is known as Hund’s rule.
• The order of electrons filling in an atom is given as

Figure 1

Pauli Exclusion Principle:

It states that in an atom no two electrons have same quantum numbers.  That is two electrons in an atom can have same three quantum number ($\text{n,}\text{l,}{\text{m}}_{\text{l}}$) but the spin quantum number differs because of electrons in same orbital spins in opposite direction.