1. Light and Quantized Energy

2. Fireworks Video
As you watch this video, answer the questions on your notes page.

3. Electromagnetic Radiation
A form of energy that exhibits wavelike behavior as it travels through space
Examples: Visible light, microwaves, x-rays, radio and television waves
Different forms of electromagnetic radiation can be seen on the electromagnetic spectrum

4. Electromagnetic Spectrum
Encompasses all forms of electromagnetic radiation, showing the differences of wavelength and frequency in the types of radiation

5. Electromagnetic Spectrum
Increasing Frequency Decreasing Wavelength

6. Characteristics of Waves
Wavelength ( λ ) – shortest distance between 2 equivalent points on a continuous waves (from crest to crest or from trough to trough)
Units of wavelength:
Usually in meters,
centimeters or
nanometers

7. Comparing Wavelengths
Which wave has a longer wavelength?
Which wave has the shorter wavelength?
long wavelength
crest
Wavelength
Wavelength
trough
short wavelength

8. Characteristics of Waves
Frequency ( v ) – number of waves that pass a given point per second
Units of frequency:
waves per second
1 / s = s -1 = Hertz

9. Another way to look at Frequency
These 2 waves are traveling at = speeds…
more crests cross the ‘finish line’ in a matter of one min.?
which wave will have
low frequency
= long wavelength
high frequency
= short wavelength

10. Characteristics of a Wave
Amplitude – wave’s height from the origin of the wave to the crest or from the origin to the trough
origin

11. Parts of a wave
Label wavelength, peak, trough and amplitude on the following wave:
peak
wavelength
amplitude
trough

12. Picking back up
Electromagnetic radiation - a form of energy that exhibits wavelike behavior as it travels through space
Electromagnetic Spectrum - Encompasses all forms of electromagnetic radiation, showing the differences of wavelength and frequency in the types of radiation
Wavelength ( λ ) – shortest distance between 2 equivalent points on a continuous waves
Frequency ( v ) – number of waves that pass a given point per second
Amplitude – wave’s height from the origin of the wave to the crest or from the origin to the trough

13. Let’s Practice! Study Guide page 25, #1-8. Energy Wave Light Speed
Wavelength
Amplitude
Frequency
Hertz

14. Can we do some more? Yes, we can!
Page 25, questions 9-11.
A and C B
2 hertz

15. Wave Calculations
All electromagnetic waves travel at the speed of light in a vacuum
Speed of light (c) = 3.00 x 108 m/s
Speed of light is equal to product of wavelength and frequency
c = λ v

16. To solve for…. To solve for wavelength: λ = c / v
To solve for frequency: v = c / λ

17. Wave Calculations Practice
Calculate the υ of a wave that has a wavelength of 5.00 x 10-6 m. ν c = λ ν
3.00 x 108 m/sec
5.00 x m = =
6.00 x Hz ν
What is the λ of radiation with a frequency of 1.50 x 1013 Hz? c λ = ν λ =
3.00 x m/sec
1.50 x Hz λ =
2.00 x m

18. Emissions of light by atoms
all elements will emit light when excited (i.e. by electricity).
atoms absorb energy and then emit an equal amount of energy in the form of electromagnetic radiation (i.e. light).
- atoms emit a characteristic wavelength
- Ne = orange - red
- Na = bright yellow
if we pass this light through a prism (separate the λ) we get an
atomic emission spectrum.
ex. of wavelengths emitted

19. Atomic Emission vs. Continuous
emission spectra are unique to particular elements.
only show certain lines of the continuous spectrum (white light).
have helped us gather a lot of info. about our universe!
atomic absorption spectra shows colors missing from the
continuous spectrum (missing λ were absorbed by the element).
continuous
absorption
emission

20. Atomic Emission Spectrum
The set of frequencies of
the electromagnetic waves
emitted by atoms of the
element
Consists of several lines
of color and not a continuous
range

21. Time to Practice
Page 26, #16-22.
False
True

22. Quantum of Energy
e- are found on certain energy levels (orbitals) around the atom.
there is a maximum of seven energy levels in an atom.
e- on the energy level closest to the nucleus have the lowest energy.
The 7th energy level has the highest energy.
- An e- requires one ‘quanta’ (minimum amount of energy gained or lost by an electron) of energy to jump to the next energy level.

23. e- at their lowest energy level are considered to be at the
ground state (most stable).
if e- absorb a quantum or more of energy (from electricity), they can jump to higher energy levels (excited state).
e- must lose energy in order to fall from the excited state back to the ground state.
- this energy is emitted in the form of electromagnetic radiation (sometimes visible)!

24. Energy Levels Principal quantum number =
= Electrons
= Protons
= Neutrons
If there are seven energy levels possible, do you think you can tell how many energy levels there would be in at atom based on looking at the periodic table?
Principal quantum number =
Period number on periodic table