1. CHAPTER 7 Quantum Theory and the Electronic Structure of Atoms
Semester 1 / 2016
7.6 Quantum Numbers
7.7 Atomic Orbital
7.8 Electronic configuration (Refer lecture)
7.9 The building-up principle

2. Quantum Numbers Principal Q. No (n) n =1,2,3,4…… Distance of e-
from the nucleus
n=1 K shell
n=2 L shell
n=2 M shell
n=2 N shell
Angular momentum
Q.No (l)
l=0  n-1
Shape of the “volume”
of space that the e- occupies
Magnetic Q.No (ml)
ml= -l….0, +l
Orientation of the orbital
in space
Electron Spin Q.No
(ms)
ms = + l 1 2 3 4 5
Orbital s p d f g h

3. Example : 1 List values of n,l,ml in 2p sub shell
i.e. n=2, l =1 , ml = -1,0,1

4. EXAMPLE 2 TOTAL NUMBER OF ORBITALS ASSOCIATED WITH PRINCIPAL QUANTUM NO “2”1
n=2 l =0 ml=0
ml=1
l =1
ml=2
ml=3

5. EXAMPLE 3 List different ways to write four quantum Numbers that designate e- in A as orbital
n=4 , l=0, ml=0, ms = +
n=4, l=0, ml=0, ms= -

6. 7.7 Atomic Orbitals
l = 0 (s orbitals)
l = 1 (p orbitals)

7. l = 2 (d orbitals)

8. 7.8 Electron Configuration
Refer Chapter 2 Lecture notes

9. 7.9 The building-up Principle
Aufbau principle : As protons are added one by one to the
Nucleus to build up the elements, electrons are similarly add
to the atomic orbitals.

10. Example : Atomi c Symbol Electron Configuration
Number 1 2 3 4 5 . 21 24 29 H He Li Be B . Sc Cr Cu
1s1
1s2
[He]2s1
[He]2s2
[He]2s22p1 .
[Ar]4s23d1
[Ar]4s13d5
[Ar]4s13d10