Atomic Nucleus PPT Physics Class 12

 Page 1


ATOMIC NUCLEUS
1. Rutherford’s Alpha Scattering Experiment
2. Distance of Closest Approach (Nuclear Size)
3. Impact Parameter
4. Composition of Nucleus
5. Atomic Number, Mass Number and Atomic Mass Unit
6. Radius of the Nucleus and Nuclear Density
7. Mass Energy Relation and Mass Defect 
8. Binding Energy and Binding Energy per Nucleon
9. Binding Energy Curve and Inferences
10.Nuclear Forces and Meson Theory
11.Radioactivity and Soddy’s Displacement Law
12.Rutherford and Soddy’s Laws of Radioactive Decay
13.Radioactive Disintegration Constant and Half-Life Period
14.Units of Radioactivity
15.Nuclear Fission and Fusion
Page 2


ATOMIC NUCLEUS
1. Rutherford’s Alpha Scattering Experiment
2. Distance of Closest Approach (Nuclear Size)
3. Impact Parameter
4. Composition of Nucleus
5. Atomic Number, Mass Number and Atomic Mass Unit
6. Radius of the Nucleus and Nuclear Density
7. Mass Energy Relation and Mass Defect 
8. Binding Energy and Binding Energy per Nucleon
9. Binding Energy Curve and Inferences
10.Nuclear Forces and Meson Theory
11.Radioactivity and Soddy’s Displacement Law
12.Rutherford and Soddy’s Laws of Radioactive Decay
13.Radioactive Disintegration Constant and Half-Life Period
14.Units of Radioactivity
15.Nuclear Fission and Fusion
Rutherford’s Alpha Scattering Experiment
+
Lead Box
Bi-214 or 
Radon
a - Beam
Thin 
Gold Foil
ZnS Screen
Gold Atom
a - Beam
Scattering angle (?)
No. of a-particles 
scattered (N)
a
a
Page 3


ATOMIC NUCLEUS
1. Rutherford’s Alpha Scattering Experiment
2. Distance of Closest Approach (Nuclear Size)
3. Impact Parameter
4. Composition of Nucleus
5. Atomic Number, Mass Number and Atomic Mass Unit
6. Radius of the Nucleus and Nuclear Density
7. Mass Energy Relation and Mass Defect 
8. Binding Energy and Binding Energy per Nucleon
9. Binding Energy Curve and Inferences
10.Nuclear Forces and Meson Theory
11.Radioactivity and Soddy’s Displacement Law
12.Rutherford and Soddy’s Laws of Radioactive Decay
13.Radioactive Disintegration Constant and Half-Life Period
14.Units of Radioactivity
15.Nuclear Fission and Fusion
Rutherford’s Alpha Scattering Experiment
+
Lead Box
Bi-214 or 
Radon
a - Beam
Thin 
Gold Foil
ZnS Screen
Gold Atom
a - Beam
Scattering angle (?)
No. of a-particles 
scattered (N)
a
a
Alpha – particle is a nucleus of helium atom carrying a charge of ‘+2e’ and 
mass equal to 4 times that of hydrogen atom.  It travels with a speed nearly 
10
4 
m/s and is highly penetrating.
Rutherford 
Experiment
Geiger & 
Marsden 
Experiment
Source of          
a-particle
Radon
86
Rn
222
Bismuth
83
Bi
214
Speed of           
a-particle
10
4
m/s 1.6 x 10
7
m/s
Thickness of 
Gold foil
10
-6
m 2.1 x 10
-7
m
Page 4


ATOMIC NUCLEUS
1. Rutherford’s Alpha Scattering Experiment
2. Distance of Closest Approach (Nuclear Size)
3. Impact Parameter
4. Composition of Nucleus
5. Atomic Number, Mass Number and Atomic Mass Unit
6. Radius of the Nucleus and Nuclear Density
7. Mass Energy Relation and Mass Defect 
8. Binding Energy and Binding Energy per Nucleon
9. Binding Energy Curve and Inferences
10.Nuclear Forces and Meson Theory
11.Radioactivity and Soddy’s Displacement Law
12.Rutherford and Soddy’s Laws of Radioactive Decay
13.Radioactive Disintegration Constant and Half-Life Period
14.Units of Radioactivity
15.Nuclear Fission and Fusion
Rutherford’s Alpha Scattering Experiment
+
Lead Box
Bi-214 or 
Radon
a - Beam
Thin 
Gold Foil
ZnS Screen
Gold Atom
a - Beam
Scattering angle (?)
No. of a-particles 
scattered (N)
a
a
Alpha – particle is a nucleus of helium atom carrying a charge of ‘+2e’ and 
mass equal to 4 times that of hydrogen atom.  It travels with a speed nearly 
10
4 
m/s and is highly penetrating.
Rutherford 
Experiment
Geiger & 
Marsden 
Experiment
Source of          
a-particle
Radon
86
Rn
222
Bismuth
83
Bi
214
Speed of           
a-particle
10
4
m/s 1.6 x 10
7
m/s
Thickness of 
Gold foil
10
-6
m 2.1 x 10
-7
m
S. No. Observation Conclusion
1 Most of the a-particles passed 
straight through the gold foil.
It indicates that most of the space 
in an atom is empty.
2 Some of the a-particles were 
scattered by only small angles, 
of the order of a few degrees.
a-particles being +vely charged and 
heavy compared to electron could 
only be deflected by heavy and 
positive region in an atom.  It 
indicates that the positive charges 
and the most of the mass of the 
atom are concentrated at the centre 
called ‘nucleus’.
3 A few a-particles (1 in 9000) 
were deflected through large 
angles (even greater than 90°).
Some of them even retraced 
their path. i.e. angle of 
deflection was 180°.
a-particles which travel towards the 
nucleus directly get retarded due to 
Coulomb’s force of repulsion and 
ultimately comes to rest and then 
fly off in the opposite direction.
N(?) a
1
sin
4
(?/2)
Page 5


ATOMIC NUCLEUS
1. Rutherford’s Alpha Scattering Experiment
2. Distance of Closest Approach (Nuclear Size)
3. Impact Parameter
4. Composition of Nucleus
5. Atomic Number, Mass Number and Atomic Mass Unit
6. Radius of the Nucleus and Nuclear Density
7. Mass Energy Relation and Mass Defect 
8. Binding Energy and Binding Energy per Nucleon
9. Binding Energy Curve and Inferences
10.Nuclear Forces and Meson Theory
11.Radioactivity and Soddy’s Displacement Law
12.Rutherford and Soddy’s Laws of Radioactive Decay
13.Radioactive Disintegration Constant and Half-Life Period
14.Units of Radioactivity
15.Nuclear Fission and Fusion
Rutherford’s Alpha Scattering Experiment
+
Lead Box
Bi-214 or 
Radon
a - Beam
Thin 
Gold Foil
ZnS Screen
Gold Atom
a - Beam
Scattering angle (?)
No. of a-particles 
scattered (N)
a
a
Alpha – particle is a nucleus of helium atom carrying a charge of ‘+2e’ and 
mass equal to 4 times that of hydrogen atom.  It travels with a speed nearly 
10
4 
m/s and is highly penetrating.
Rutherford 
Experiment
Geiger & 
Marsden 
Experiment
Source of          
a-particle
Radon
86
Rn
222
Bismuth
83
Bi
214
Speed of           
a-particle
10
4
m/s 1.6 x 10
7
m/s
Thickness of 
Gold foil
10
-6
m 2.1 x 10
-7
m
S. No. Observation Conclusion
1 Most of the a-particles passed 
straight through the gold foil.
It indicates that most of the space 
in an atom is empty.
2 Some of the a-particles were 
scattered by only small angles, 
of the order of a few degrees.
a-particles being +vely charged and 
heavy compared to electron could 
only be deflected by heavy and 
positive region in an atom.  It 
indicates that the positive charges 
and the most of the mass of the 
atom are concentrated at the centre 
called ‘nucleus’.
3 A few a-particles (1 in 9000) 
were deflected through large 
angles (even greater than 90°).
Some of them even retraced 
their path. i.e. angle of 
deflection was 180°.
a-particles which travel towards the 
nucleus directly get retarded due to 
Coulomb’s force of repulsion and 
ultimately comes to rest and then 
fly off in the opposite direction.
N(?) a
1
sin
4
(?/2)
Distance of Closest Approach (Nuclear size):
+
r
0
When the distance between a-particle 
and the nucleus is equal to the distance 
of the closest approach (r
0
), the a-particle 
comes to rest.
At this point or distance, the kinetic 
energy of a-particle is completely 
converted into electric potential energy 
of the system.
½ mu
2
=
1
4pe
0
2 Ze
2
r
0
r
0 
=
1
4pe
0
2 Ze
2
½ mu
2