Question

5. (a) State the strong form of the Pauli Principle which describes the symmetry properties of a two-particle state function under exchange of the particles, and explain the difference between fermions and bosons. 2 marks) (b) By constructing appropriate two-particle state functions show why it is that no two identical fermions can occupy the same spatial state, i.e. a state specified by quantum numbers n, 1, mi, unless they have different spins. 4 marks) (c) Use the Bohr-Stoner principle (or aufbau principle) to construct and explain the ground state configurations of the first thirteen elements. Give the ground state configuration for each element in the table below Element Z Configuration Outermost occupied shell Li 0 Mg Al 12 13

Answer 1

5 )

a )

Pauli's exclusion principle is states that the two or more identical fermions cannot go or occupy the same quantum state within

a quantum system simultaneously and precisely.

b )

it very simple that the two fermions that are not in same quantum state,

because no two electron have same spin.

that will be +1/2 or -1/2 spin.

c )

Element	Z	Electronic configuration	Outer most Occupied Shell
Hydrogen	1	1s1	K
Helium	2	1s2
Lithium	3	1s2 2s1	L
Beryllium	4	1s2 2s2
Boron	5	1s2 2s22p1
Carbon	6	1s2 2s22p2
Nitrogen	7	1s2 2s22p3
Oxygen	8	1s2 2s22p4
Fluorine	9	1s2 2s22p5
Neon	10	1s2 2s22p6
Sodium	11	1s2 2s22p63s1	M
Magnesium	12	1s2 2s22p63s2
Aluminum	13	1s2 2s22p63s23p1