Need of a new approach to Atomic structure

1. What is Quantum
mechanics?
Mr. Mithil Fal Desai, Ph. D.
Assistant Professor in Chemistry
Shree Mallikarjun and Shri Chetan Manju
Desai College
Canacona, Goa

2. What was the Need of a new approach to Atomic structure?
Various limitation associated with Bohr’s model of atomic structure.
As Bohr’s model
-based on assumptions.
-based on Classical mechanics.
-cannot explain the fine structure (hyperfine splitting) in spectrum of
hydrogen.
-cannot explain Stark and Zeeman effect.

3. Classical mechanics Quantum mechanics
1 Based on Newton’s Law Based on Heisenberg
uncertainty principle, de
Broglie, Plank concept
2 Valid for macroscopic
matter
Deals with microscopic
(atomic/subatomic) matter
3 Velocity and position of
matter is certain
Deals with probability function
4 Matter as particle Dual nature of matter
Difference between Classical and Quantum mechanics

4. Classical mechanics

5. Classical mechanics

6. Energy
Classical Mechanics Quantum Mechanics
Illustration

7. It is a discrete quantity
of energy proportional
in magnitude to the
frequency of the
radiation it represents.
What is Quantum?
E α ν

8. Energy occurs in
discreet "packets"
called photons
Energy is Quantised
E α ν

9. Energy is Quantised

10. -1.5
-1
-0.5
0
0.5
1
1.5
0 5 10 15 20
-1.5
-1
-0.5
0
0.5
1
1.5
2
0 5 10 15 20
Sin1 Sin2
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
0 5 10 15 20
Sin1 + Sin2
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20
Interference

11. Sin (0) = 0
Sin (90) = 1
Sin (x) = y
f(x) = y
Understanding f(x)
Function
Independent
variable
Dependent
variable
-1.5
-1
-0.5
0
0.5
1
1.5
0 200 400 600 800 1000 1200

12. Understanding f(x)
Function
Independent
variable
Dependent
variablef(x) = y
y = mx + C
10 = 5(2) + 0