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

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

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

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

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= -

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

l = 2 (d orbitals)

7.8 Electron Configuration Refer Chapter 2 Lecture notes

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.

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