CHEM 1331 REVIEW
CHAPTER 7
LIGHT
Wavelength (
λ
)
Frequency (
ν
)
Speed (c) = 3 x 10
8
m/s
c =
λν
Spectrum in order or INCREASING FREQUENCY (DECREASING WAVELENGTH)
Radio < micro < infra red < visible < ultraviolet < xray < gamma ray
In visible:
red < orange < yellow < green < blue < violet
Planck:
Light energy comes in packets (PHOTONS):
E = h
ν
J
Einstein:
Photoelectric effect – photons can be thought of as particles
ELECTRONS IN ATOMS
Bohr Model
Energy levels quantized
Electrons in orbits with specific quantum numbers related to energy
Spectra due to electrons moving up in energy (absorption) or down in energy (emission)
E
∝
[1/n
1
2
– 1/n
2
2
] when n
1
and n
2
are energy level quantum numbers
(can also get
ν
or 1/
λ
proportional using correct constants,
ℜ
)
de Broglie
Everything has a wavelength:
λ
= h/mv (not important for us, important for electrons)
Heisenberg
Uncertainty Principle – can’t know position and speed (momentum, energy) of electron
Orbital
Volume of space in which are most likely to find electron of particular energy
Described by WAVEFUNCTION (mathematical equation,
ψ
)
Schrodinger
Equation:
H
ψ
= E
ψ
– relates Energy to
ψ
.
Quantum Numbers (allowed values in wavefunction for particular E values) – all whole #’s
n
principal
describes size
can be 1, 2, 3, 4….
(affects energy)
⎝
azimuthal
describes shape
can have values from 0 to n1 (affects energy)
m
magnetic
describes orientation can have values from –
⎝
to +
⎝
if
⎝
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 Spring '08
 bott
 Energy, Photon

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