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Chapter 5
 Nuclear
atomic model did not explain
how the atom’s electrons are arranged
in the space around the nucleus.
 Did not explain the differences in
chemical behavior among the
 Scientists discovered that an element’s
chemical behavior is related to the
arrangement of the electrons in its
 Electromagnetic
radiation is a form of energy
that exhibits wavelike behavior as it travels
through space. (Ex: visible light, radio
waves, X rays)
 Wavelength is the shortest distance between
equivalent points on a continuous wave
(units: meters, centimeters, nanometers)
 Frequency is the number of waves that pass
a given point per second. (units: hertz; one
hertz (Hz) = one wave per second = s^ -1)
 Amplitude of a wave is the wave’s height
from the middle to the top or from the
middle to the bottom
 The
speed of light (c) is the product of its
wavelength (λ) and its frequency (ν).
 C = λν
 As wavelength increases, frequency
decreases and as frequency increases,
wavelength decreases.
 All electromagnetic waves have the same
speed, but have different wavelengths
and frequencies.
Higher Frequency
Lower Frequency
 Sunlight
is an example of white light.
 When sunlight passes through a prism, you
see a continuous spectrum of colors. (visible
 Rainbows form when drops of water in the
air scatters white light from the sun into the
spectrum of colors that you see.
 The electromagnetic spectrum includes all
forms of electromagnetic radiation.
 The
sequence of the visible spectrum is red,
orange, yellow, green, blue, indigo, violet
(Roy G. Biv)
 As frequency increases, energy increases.
Energy increases     
 What
is the wavelength of a microwave
having a frequency of 3.44 X 109 Hz (or 1/s)?
C = λν
3. 00 X 108 m/s = λ (3.44 X 109 Hz)
λ = 8.72 X 10-2 m
 What
is the frequency of green light, which
has a wavelength of 4.90 X 10-7 m?
 An X-ray has a wavelength of 1.15 X 10-10 m.
What is its frequency?
 What is the wavelength of an
electromagnetic wave that has a frequency
of 7.8 X 106 Hz?
 The
temperature of an object is a measure of
the average kinetic energy of its particles.
 When objects are heated up, they gain more
 Max Planck studied why objects gave off light
when heated.
 He found that matter can gain or lose energy
only in small, specific amounts called
 A quantum is the minimum amount of energy
that can be gained or lost by an atom.
 Planck
proved that the energy of a
quantum is related to the frequency of the
emitted radiation.
 E = hν
 E = energy; h = Planck’s constant;
ν = frequency
 Planck’s constant = 6.626 X 10-34 J·s
 Unit for energy = joules (J)
 Matter can only have certain amounts of energy
 No amounts of energy between these values
exist (Child building wall of blocks)
 In
the photoelectric effect, electrons called
photoelectrons are given off from a metal’s
surface when light of a certain frequency
shines on the surface.
 Einstein said electromagnetic radiation has
both wavelike and particle-like natures.
 So a beam of light has many wavelike
characteristics, but also is a stream of tiny
particles, or bundles of energy, called
 A photon is a particle of electromagnetic
radiation with no mass that carries a
quantum of energy.
 What
is the energy of a photon from the
violet portion of the rainbow if it has a
frequency of 7.23 X 1014 s-1 ?
E = hν
E = (6.626 X 10-34 J·s) x (7.23 X 1014 s-1)
E = 4.79 X 10-19 J
 What
is the energy of each of the following
types of radiation?
6.32 X 1020 s-1
9.50 X 1013 Hz
1.05 X 10 s-1
 The
atomic emission spectrum of an element
is the set of frequencies of the
electromagnetic waves emitted by atoms of
the element.
 Only certain colors appear in a certain
element’s atomic emission spectrum so only
certain frequencies of light are emitted.
 Bohr
studied the hydrogen atom to learn
about energy states.
 The lowest energy state possible of an atom
is called its ground state.
 When an atom gains energy, it is said to be in
an excited state.
 Bohr also suggested that electrons move
around the nucleus only in certain circular
 The smaller the electron’s orbit, the lower
energy level the atom is in.
 The larger the electron’s orbit, the higher
energy level the atom is in.
assigned a quantum number to
each orbit.
The quantum numbers are n=1, n=2,
n=3, and so on.
Bohr’s model was the foundation for
atomic models that came later, but
his model was actually wrong
because electrons do not move
around the nucleus in orbits.
Broglie studied to see if electrons
(particles) could behave like waves.
His equation is λ = h/mv
Wavelength = Planck’s constant/
mass x volume
His equation predicts that all moving
particles have wave characteristics
 The
Heisenberg uncertainty principle says
that it is impossible to know both the
velocity and position of a particle at the
same time.
 Schrodinger’s quantum mechanical model
of the atom describes atomic orbitals,
which are regions around the nucleus
where electrons can be.
 Atomic orbitals do not have an exact size.
 Principal
quantum numbers indicate the size
and energies of atomic orbitals.
 The letter ‘n’ represents an atom’s major
energy levels called principal energy levels.
 Principal energy levels contain energy
 Principal energy level 1 has 1 sublevel.
 Principal energy level 2 has 2 sublevels.
 Principal energy level 3 has 3 sublevels and
so on.