1. Atomic Structure
the wave nature of light 1 2 3
2 Hz
4 Hz
6 Hz 
= frequency
(s-1)
(Hz) 
= wavelength
(m)
u =  
diffraction
velocity
ms-1

2. Electromagnetic radiation
magnetic field
electrical field 
= frequency
(s-1)
(Hz) 
= wavelength
(m)
u =  
= c
= speed of light
= x 108 ms-1

3. Problems not answered by classical physics1.
Black body radiation
1000 K
red
All objects at T > 0K emit radiation
1500 K
orange
atomic and molecular motion
2000 K
white
E = n h ν
energy is
quantized
frequency
Planck’s constant
h =
6.626 x 10-34J s
integer
Max Planck
1900
equation explained data
but
only certain quantities of energy could be emitted

4. Problems not answered by classical physics2.
Photoelectric effect e- e- e- e- e- e-
light
lens
slit
prism uv v b y o r ir
potassium
kinetic energy of e-
independent of intensity
dependent on wavelength
number of e-
independent of 
(above threshold)
dependent on intensity

5. Problems not answered by classical physics2.
Photoelectric effect
Einstein
1905
light as particles
photons
with energy
= hν e- e- e-
low energy photons
no electrons emitted
above threshold energy
all photons effective
more photons
more e- emitted
higher energy photons
higher K.E. to e-

6. Problems not answered by classical physics3.
Line spectra of atoms
excited elements emit radiation
specific frequencies Na
Bohr
1913 Hg H He

7. Bohr atom
n =
quantum number
n = 1
ground energy state
stable
n > 1
excited states
unstable
n = ∞
electron leaves atom ΔE
= hν 1
nf2 1
ni2
ΔE =
- RH Z2 -
nuclear charge
H = 1
2.178 x 10-18J

8. Bohr atom 1
nf2 1
ni2
ΔE = x 10-18J -
from
n = 4
to n = 2 1 22 1 42
ΔE =
x 10-18J -
ΔE =
x J
ΔE = hν
4.084 x J =
6.626 x 10-34Js ν
c = 
ν =
6.17 x 1014s-1
 = 486 nm
green H line

9. Bohr atom
Problems 1.
Only works for H,
He+,
Li2+
1 electron systems 2.
Doesn’t explain why e- revolves at a fixed distance from nucleus
De Broglie
1924
If light waves behave like particles,
particles behave like light waves

10. De Broglie
If light waves behave like particles,
particles behave like light waves
 = h/
 = momentum = mv
 = h/mv

11. De Broglie
 = h/
 = h/m
Calculate the wavelength of an e-
moving 62 ms-1
 =
6.626 x Js /
9.110 x 10-31kg
x 62 ms-1
 = 1.2 x 10-5 m
= 1.2 x 104 nm
= infrared
De Broglie
accelerate e-
wavelength of x-rays

12. diffraction
x-ray diffraction
x-rays
 =
7.1 nm
same scale as atoms
 = h/mv
accelerate e- 
= x-ray
accelerated e-
to 1.5 x 105 ms-1
electron diffraction
 =
6.626 x J s
(9.110 x 10-31kg)
(1.5 x 105 ms-1)
 = 5.0 nm
J = kg x m x s-2