ChemCatalyst – Please answer the
following in your notebook
Countless products are advertised on TV with
the promise of reducing acid indigestion.
1. What is acid indigestion?
2. What does acid have to do with your stomach?
3. How do you think antacids work?
The Lab
• Indicator: An indicator is a molecular substance that
changes color when it comes into contact with an
acid or a base.
• Work in your table groups
• Follow the directions as written!
• Acids and bases are corrosive. Do not get solutions
on skin. In case of a spill, rinse thoroughly with
water.
• Wear safety goggles at all times.
Please take out your notes for 6.1-6.2.
You will also need a calculator today.
Grading Changes for Semester 2
• 50% tests and quizzes (same as last semester)
• 10% homework (same as last semester)
• 35% labs (5% less than last semester)
– Most of the post-AP test work will go into this
category as well
Grading Changes for Semester 2
• 50% tests and quizzes (same as last semester)
• 10% homework (same as last semester)
• 35% labs (5% less than last semester)
– Most of the post-AP test work will go into this
category as well
• 5% notes from reading/tutorials
– May not check every day, but reserve the right to
check at any time
– Will not collect (so you can keep doing them in
your notebook)
Electron Structure and Behavior
• 2 Beliefs
– Light as a wave (6.1)
– Light as a particle (6.2)
Light as a Wave
• Electromagnetic spectrum
– Organized by increasing wavelength (λ – lambda)
– c = λν
– c = speed of light = 3.00 x 108 m/s
– λ = wavelength in meters
– ν = frequency in Hz (1 Hz = 1 sec-1) [per second]
• Nu
– [wave drawings]
What are the basic SI units for
1. the wavelength of light?
2. the frequency of light?
3. the speed of light?
Label each of the following statements as true or false. For
those that are false, correct the statement.
1. Visible light is a form of electromagnetic radiation.
2. The frequency of radiation increases as the wavelength
increases.
3. Ultraviolet light has shorter wavelengths than visible light.
4. Electromagnetic radiation and sound waves travel at the
same speed.
1. What is the frequency of radiation that has a
wavelength of 0.589 pm? (1 pm = 10-12 m)
1. What is the frequency of radiation that has a
wavelength of 0.589 pm?
2. What is the wavelength of radiation that has
a frequency of 5.11 x 10-11 s-1?
1. What is the frequency of radiation that has a
wavelength of 0.589 pm?
2. What is the wavelength of radiation that has a
frequency of 5.11 x 10-11 s-1?
3. Would the radiations in part 1 or part 2 be visible
to the human eye?
1. What is the frequency of radiation that has a
wavelength of 0.589 pm?
2. What is the wavelength of radiation that has
a frequency of 5.11 x 10-11 s-1?
3. Would the radiations in part 1 or part 2 be
visible to the human eye?
4. What distance does electromagnetic
radiation travel in 6.54 s?
Excited mercury atoms emit light strongly at a
wavelength of 436 nm. What is the frequency of
this radiation? Using Figure 6.4, predict the
color associated with this wavelength.
Take 2 minutes to write a 1-2 sentence summary
of section 6.1 (light as a wave)
Light as a Particle
• Planck tells us that atoms release light as chunks
of some minimum size
– If something is quantized (or quantum) it happens in
fixed increments
– Stairs are quantized, a ramp is not
– Energy is released in whole number intervals
• E = hv
–
–
–
–
E = energy
h = Planck’s constant; 6.63 x 10-34 J·s
v = frequency in Hz
Matter can only emit and absorb energy in integer
increments of hv (eg: hv, 2hv, 3hv, etc)
Light as a Particle
• Einstein = photoelectric effect
– Quantums = photons
• A photon is a particle of energy
– When the surface of a metal is struck by light,
electrons are emitted
– Work function – amount of energy required for
electrons to overcome attractive forces holding
them in a metal
– If the photons striking the metal have less energy
than the work function, electrons will not escape
“To better understand what a photon is, imagine
you have a light source that produces radiation
of a single wavelength. Further suppose you
could switch the light on and off faster and
faster to provide ever-smaller bursts of energy.
Einstein’s photon theory tells us that you would
eventually come to the smallest energy burst,
given by E = hv. This smallest burst contains a
single photon of light.”
1. What does it mean when we say energy is
quantized?
2. Calculate the smallest increment of energy (a
quantum) that can be emitted or absorbed at a
wavelength of 812 nm.
3. Calculate the energy of a photon of frequency
2.72x1013 s-1.
4. What wavelength of radiation has photons of
energy 7.84x10-18 J? In what portion of the
electromagnetic spectrum would this radiation
be found?
5. One type of sunburn occurs when exposure to
UV light of wavelength in the vicinity of 325 nm.
a. What is the energy of a photon of this
wavelength?
5. One type of sunburn occurs when exposure to
UV light of wavelength in the vicinity of 325 nm.
a. What is the energy of a photon of this
wavelength?
b. What is the energy of a mole of these photons?
5. One type of sunburn occurs when exposure to
UV light of wavelength in the vicinity of 325 nm.
a. What is the energy of a photon of this
wavelength?
b. What is the energy of a mole of these photons?
c. How many photons are in a 1.00 mJ burst of this
radiation?
Take 2 minutes to write a 1-2 sentence summary
of section 6.2 (light as a particle)
Homework
• Sections 6.3-6.4
• Quiz Friday on 6.1-6.4