Light & Atomic Spectra, Planck’s Constant
Types of Light
_____________light is the light that humans can see
Did you know?
 Dogs can see only shades of ________________
 and some insects can see light from the ultraviolet
part of the spectrum
Seeing the Light
 Visible light is the light that humans can see.
 More specifically, you see the light that
_____________________ by objects.
 Green plants are green because they absorb all of the
colors of the visible spectrum ___________________
the ______________ color (you could also say the
green wavelengths).
Red
A red wall is red to your eyes because it is
_________________________ light from the red wavelengths.
electromagnetic radiation
 Visible light is only one small portion of a family of
waves called electromagnetic (_____) radiation.
 EM waves includes radio waves, _____, infared,
microwave, ___________, gamma rays
 Visible light is near the ___________ of the spectrum.
ROY-G-BIV
 represents all of the colors in the visible spectrum of
light. R (red) - O (orange) - Y (yellow) - G (green) - B
(blue) - I (indigo) - V (violet).
 Red has the ____________________ and violet has
the _________________________.
 You could also say that red is the
____________energetic and violet is the
______________energetic of the visible spectrum.
Prisms
 When refraction is at work in a prism it breaks the
beam of visible light into its ___________________.
 A prism is made up of two planar surfaces at an
angle.
 It uses the ___________________ of light in glass to
its advantage by _________________ the light twice.
 When the light ray leaves the prism, it speeds up
again (entering the air) and _______________ a
second time.
 That second dispersal creates the colorful spectrum of
colors.
Light waves are classified by frequency of wavelength
 Low frequency= __________________________
 High frequency= __________________________
Parts of a wave
 ____________________
 height of the wave from normal to highest point.
 ____________________
 the distance from origin to origin, crest to crest
 ____________________
 1 wave per period
 measured in Hz (1Hz = 1wave per second).
In 1900, Max Planck
 was working on the problem of how the radiation an
object emits is related to its temperature.
 ____________________, the constant of
proportionality relating the energy of a photon to its
frequency; or h, and it has the value
The formula
 The energy E contained in a photon, the smallest
possible 'packet' of energy, is directly proportional to
the frequency f :
 EQUATION: Ephoton____________________
 Ephoton = (6.626176 x 10-34J*s) *f (frequency)
 and conversely:
 f(frequency)= Ephoton / (6.626176 x 10-34J*s)
 Frequency SI units are Hz or 1/s or s-1
 Example Problem: Calculate the energy in J of a
quantum of radiant energy (the energy of a photon)
with a frequency of 5.00 x 1015 Hz.
1st list the knowns:
Frequency (f) =
h= 6.626 x 10-34 J*s (Planck’s constant)
Unknown: E
Solve for the unknown:
E= h x f
E=
E=
 What is the energy of a photon of microwave radiation
with a frequency of 3.20 x 10-11 Hz?

What is the energy of a photon of green light with a
frequency of 5.80 x 1014 Hz?
Einstein
 Based on Planck's work, Einstein proposed that light
also delivers its energy in chunks; light would then
consist of little particles, or quanta, called
____________________, each with an energy of
Planck's constant times its frequency.
 c=λf
 c=speed of light = 3.0 x 108 m/s
 λ= wavelength (make sure it is in meters (m) so the
units will match)
 f=frequency in Hz
 Calculate the wavelength of the yellow light emitted by
a sodium lamp if the frequency of the radiation is 5.10
x 1014 Hz
List the knowns:
Frequency (f) =
c=speed of light =
Unknown: λ in m
λ=c/f
λ=
=
 What is the wavelength of radiation with a frequency
of 1.50 x 1013 Hz
 What frequency is radiation with a wavelength of 5.00
x 10-6 cm?
It's all Energy
 The quantum theory says light consists of very small
bundles of energy/particles called
____________________.
 ____________________ determines: energy & type
of EM radiation
 ____________________: states how much radiation
is present
Photons determine how bright the light is….
 Lots of photons give a ____________________, more
intense type of light.
 Fewer photons give a ____________________and
less intense light.
Think of a dimmer switch
When you use the dimmer switch on the wall, you are
decreasing the number of photons sent from the light bulb.
The type of light is the same while the amount has changed.
Flame Test Lab
 Flame tests are used to identify the presence of a
relatively small number of ____________________in
a compound.
 Flame colors are produced from the movement of the
____________________ in the metal ions present in
the compounds.
So in the flame,
 electrons get ____________________and pushed to
____________________levels
 When they fall back down, they give off
____________________ of light of different
____________________, based upon how far they
fall.
For example, a sodium (na) ion in an unexcited state has
the structure 1s22s22p6.
 When heated: electrons gain energy and jump into
any of the empty orbitals at higher levels –
 for example, into the 7s or 6p or 4d, depending on
how much energy is ____________________ from
the flame.
 Because the electrons are now at a higher and more
energetically ____________________, they tend to
fall back down to where they were before
 It might fall straight back or jump through many
levels…
 Each of these jumps involves a specific amount of
energy being released as light energy, and each
corresponds to a particular ____________________.
 Whatever color is produced, tells you what
____________________.
 This is a great way to determine an unknown
substance…