Wave Nature of Matter

De Broglie Wavelength

mv

h

Wave-particle duality apply also to matter.

Early Models of Atoms

Thomson’s Model

Rutherford’s Model

Atomic Spectra

The Rutherford model, as it stood, was unable to explain why atoms emit line spectra.

The Bohr Model

Bohr’s First Postulate

The angular momentum of electron is quantized.

Allowed Angular Momenta

2

hnLn

Allowed Radii

0

22

2

1

1

2

4

1

;4

k

mke

hr

rZ

nrn

Bohr’s Second Postulate

An electron doesn’t radiate when it is in one of the allowed orbits (stationary state).

Energy Levels of Atom

22

422 12

nh

eZEn

Bohr’s Third Postulate

A single photon is emitted whenever an electron jumps down from one orbit to another.

lowerupper EEhf

De Broglie’s Hypothesis Applied to Atoms