Rutherford Scattering And Introduction To Bohr Model L-8
Rutherford Scattering and Introduction to Bohr Model
Rutherford Scattering And Introduction To Bohr Model L-8
Model of Atoms
Two major Contenders
Plum pudding model (Thompson)
Planetary Moel (Rudherford)
Rutherford Scattering And Introduction To Bohr Model L-8
Experimental Results
Source : 83214Bi;
Energy of α particles 5.5 MeV
Taget : A very thin gold foil (2.1×10−7m)
Detector : Zinc sulphide (scintillation) + Microscope
Rutherford Scattering And Introduction To Bohr Model L-8
Rutherford Scattering
+ve charge distribution
Rutherford Scattering And Introduction To Bohr Model L-8
Tiny Fraction of an Angstron
r21→ Outside the sphere
21mv2
4πϵ0θ1θ2
z∼100
5.5 MeV
Tiny fraction of an angstron
1Ao
0.1Ao
Rutherford Scattering And Introduction To Bohr Model L-8
Plum Pudding Model Predictions
Rutherford Scattering And Introduction To Bohr Model L-8
Plum Pudding Model Predictions
Gravitation : r2GMm
Coulomb : 4πϵ01r2Q1,Q2
In an inverse square field : F∼r21
Most general tranjectory is either
(i) Ellipse → sphere
Ellipse → st line
(ii) Hyperbold → Parabola
Rutherford Scattering And Introduction To Bohr Model L-8
Plum Pudding Model Predictions
Rutherford Scattering And Introduction To Bohr Model L-8
Experimental Results
The positive charge is distributed in a very small region in the atom
rp∼10−4rat
Rutherford Scattering And Introduction To Bohr Model L-8
Plantery Model
Electron
Proton
Neutron
Ao
1Ao=10−8cm
≃10−10m
0.1nm
10−13cm
10−15fm
Rutherford Scattering And Introduction To Bohr Model L-8
Electromagnetic Theory
Charge at rest
Electrostatic field
v→ No acceleration.
E,B
Electromagnetic wave
Radiation
Rutherford Scattering And Introduction To Bohr Model L-8
Atomic Structure
10−15m
∼10−9
Rutherford Scattering And Introduction To Bohr Model L-8
Stability Problems
Rutherford Scattering And Introduction To Bohr Model L-8
Stability Problems
Rutherford Scattering And Introduction To Bohr Model L-8
Spectral Problems
Rutherford Scattering And Introduction To Bohr Model L-8
Rydberg Constant
Ry → Rydberg Constant
Ry(n221−n421)
n1,n2 are integers
n1=1;n2=2,3...
n2=2,3...→ integers
n4=1;n2=3,4....→ Balmer
Rutherford Scattering And Introduction To Bohr Model L-8
Rutherford Scattering
1) Atom is mostly empty.
10−15m
∼10−10m
2) This model is not in agreement with other observations.
(a) Spectral of radiation are discrete
(b) Atoms are all stale
10−9s electrons model
Rutherford Scattering And Introduction To Bohr Model L-8
Collapsed into the Nucleus
Electrons do not collapse.
There must be a lowest orbit which is stable.
Two Tasks at hand
(1) Understand discrete spectrum
(2) Understand stability
Bohr Model
Rutherford Scattering And Introduction To Bohr Model L-8
Bohr Model
[h] → Energy × Time
[h] → Angular mumentum → Bohr exploited
Rutherford Scattering And Introduction To Bohr Model L-8
Enunciate a Rule
Emission of Radiation by accelerating electrons are also governed by new physics.
We need new principle
Bohr model is Semi classical
Rutherford Scattering And Introduction To Bohr Model L-8
Thank You
Rutherford Scattering And Introduction To Bohr Model L-8 Rutherford Scattering and Introduction to Bohr Model $\rightarrow$ $\rightarrow$ Rutherford Scattering and Introduction to Bohr Model $\rightarrow$ Model of Atoms $\rightarrow$ Experimental Results