Exchange energy https://www.youtube.com/watch?v=bT5rL_hERpY

1. Concept of Exchange energy
(Eex)
Dr. Mithil Fal Desai
Shree Mallikarjun and Shri Chetan Manju Desai College
Canacona Goa

2. Relative energies of atomic orbitals
1s
2s
2p
3d
3s
3p
Z<20
Z>20
Energy
4s
4p
4d
4f

3. Electronic configurations of the atoms
Atomic Number Name Symbol Orbitals Shells
1 Hydrogen H 1s1 1
2 Helium He 1s2 2
3 Lithium Li [He] 2s1 2,1
4 Beryllium Be [He] 2s2 2,2
5 Boron B [He] 2s2, 2p1 2,3
6 Carbon C [He] 2s2, 2p2 2,4
7 Nitrogen N [He] 2s2, 2p3 2,5
8 Oxygen O [He] 2s2, 2p4 2,6
9 Fluorine F [He] 2s2, 2p5 2,7
10 Neon Ne [He] 2s2, 2p6 2,8
11 Sodium Na [Ne] 3s1 2,8,1
12 Magnesium Mg [Ne] 3s2 2,8,2
13 Aluminum Al [Ne] 3s2, 3p1 2,8,3
14 Silicon Si [Ne] 3s2, 3p2 2,8,4
15 Phosphorus P [Ne] 3s2, 3p3 2,8,5
16 Sulfur S [Ne] 3s2, 3p4 2,8,6
17 Chlorine Cl [Ne] 3s2, 3p5 2,8,7
18 Argon Ar [Ne] 3s2, 3p6 2,8,8
19 Potassium K [Ar] 4s1 2,8,8,1
20 Calcium Ca [Ar] 4s2 2,8,8,2
21 Scandium Sc [Ar] 3d1, 4s2 2,8,9,2
22 Titanium Ti [Ar] 3d2, 4s2 2,8,10,2
23 Vanadium V [Ar] 3d3, 4s2 2,8,11,2
24 Chromium Cr [Ar] 3d5, 4s1 2,8,13,1
25 Manganese Mn [Ar] 3d5, 4s2 2,8,13,2
26 Iron Fe [Ar] 3d6, 4s2 2,8,14,2
27 Cobalt Co [Ar] 3d7, 4s2 2,8,15,2
28 Nickel Ni [Ar] 3d8, 4s2 2,8,16,2
29 Copper Cu [Ar] 3d10, 4s1 2,8,18,1
30 Zinc Zn [Ar] 3d10, 4s2 2,8,18,2
Anomalous electronic configurations

4. Anomalous electronic configurations
Atomic
Number Name Symbol Orbitals
24 Chromium Cr [Ar] 3d5, 4s1
29 Copper Cu [Ar] 3d10, 4s1
More stable
Exchange energy (Eex)

5. Exchange energy (Eex)
𝐸𝑒𝑥 = ෍
𝑁(𝑁 − 1)
2
𝐾
Nitrogen[He] 2s2, 2p3
2px 2py 2pz 2px 2py 2pz
N- number of electrons with parallel spin
K- constant
or
Electrons can exchange their position
with other electrons having parallel spin.

6. Exchange energy (Eex)
𝐸𝑒𝑥 = ෍
𝑁(𝑁 − 1)
2
𝐾
2px 2py 2pz 2px 2py 2pz
N- number of electrons with parallel spin
K- constant
or
Electrons can exchange their position
with other electrons having parallel spin.
Nitrogen[He] 2s2, 2p3

7. 𝐸𝑒𝑥 = ෍
3(3 − 1)
2
𝐾
= 3K
𝐸𝑒𝑥 = ෍
2(2 − 1)
2
𝐾
= 1K
Exchange energy (Eex)
𝐸𝑒𝑥 = ෍
𝑁(𝑁 − 1)
2
𝐾
N- number of electrons with parallel spin
K- constant
2px 2py 2pz 2px 2py 2pz
or
Nitrogen[He] 2s2, 2p3