2. Draw and identify the features of a wave;
Describe the relationship among the
frequency, wavelength, and energy of light;
Identify the general ranges of electromagnetic
radiation and their relative wavelengths and
frequencies;
Explain the source of atomic emission
spectra;
Explain how the frequencies of emitted light
are related to changes in electron energy
3. Light made of electromagnetic waves
◦ Considered to be quanta of energy called photons
◦ Has properties of particles and waves
Wavelength (λ)
:distance
between crests
Amplitude
4. Frequency (ν): number of wave cycles to pass a
given point per unit of time
◦ SI unit is Hertz (Hz), or s-1
Two are related by the formula:
Since c is constant, λ and ν are inversely
proportional
If one is big, the other is small
speed of light
3 x 108m/s
5. If you know either λ or ν, can solve for other
Example: What is the wavelength of a wave
with frequency equal to 5.10 x 1014 Hz?
c
c
Rearrange
6.
7. Energy of light is related to frequency
◦ Higher the frequency, more energy
Visible light is small slice in the middle of
spectrum
◦ Red is lowest ν(longest λ) that the human eye “sees”
8. Ground state: electrons in lowest
possible energy level
Excited state: atoms absorb energy and
electrons move to higher energy levels
◦ Once energy source is removed, electrons
drop back down to ground state
◦ Emit quanta of energy in the form of… light
(sometimes visible)
9. Atomic emission spectrum: pattern of
discreet lines given off by electrons dropping
to ground state
◦ Energy levels are quantized
◦ Each line represents a frequency (energy) that is
directly proportional to the energy lost by the
electron
◦ No two elements have exactly the same spectrum
10. Each drop an electron
makes relates to a
specific frequency of
energy
Not all is in visible
range, but always at
discreet frequencies
(not continuous)
11. Draw and identify the features of a wave?
Describe the relationship among the
frequency, wavelength, and energy of light?
Identify the general ranges of electromagnetic
radiation and their relative wavelengths and
frequencies?
Explain the source of atomic emission
spectra?
Explain how the frequencies of emitted light
are related to changes in electron energy?
