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Atoms, Energy, Electrons,
Oh My!!
Chemistry
February, 2011
Chapter 11
The Atom
• What are the 3 parts that make up the atom?
• Protons (+), neutrons, electrons(-)
• Which particles make up the mass of the
atom?
• What does the atomic number on the periodic
table tell us?
• What is the electron’s job?
• What can we say about a “group” of elements
on the periodic table?
Remembering Rutherford
• Gold foil experiment
that resulted in the
“nuclear atom”
• What about those
electrons?
Electromagnetic Radiation
• To better understand the behavior of
electrons, let’s look at the relationship
between energy and light.
• How does light travel?
• In waves: energy is transmitted by light
• Electromagnetic radiation.
Electromagnetic Radiation
• A wave has 3 important parts to it:
• Wavelength :lambda,
– The distance between 2 consecutive wave peaks
• Frequency: nu,
– How many waves per second
• Speed of the wave through space
– Speed of light = 2.99 x 108 m/s
Electromagnetic Radiation
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Some examples of light waves:
X rays
Microwaves
Radio waves
They all differ in their wavelengths
They all differ in the amount of energy
transmitted
Electromagnetic Radiation
• Roy G. Biv
Electromagnetic Radiation
• What do you think has more energy, UV light
or X rays?
Electromagnetic Radiation
• The length of the wavelength (and color)
correspond to the amount of energy the
wave carries.
• The longer the wavelength of light, the
lower the amount of energy
• Compare the color of the cations of our flame
test.
• Na+ vs. Li+
• Which one has more energy as it is heated by
a flame?
Light: the Flip-flopper
• Light: a bit of a “flip-flopper”
• So light likes to travel through space in waves and
transmit energy
• Light also likes to behave like particles moving
through space as photons, little packets of energy
Flame test : revisited
Hydrogen
Hydrogen
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Let’s review some terms
Atomic States:
Excited state- atom with extra energy
Ground state- atom in the lowest
possible state
• What happens to the H atom when it
absorbs energy?
• It enters an excited state!
Hydrogen
Hydrogen
• What happens to the H atom when it releases
the excess energy?
Hydrogen
• What is an Energy
Level Diagram?
• What does it show us?
• The ground and excited
states of a particular
atom.
• The energy of the
photon emitted
corresponds to the
energy used by the
atom to get to the
excited state.
Hydrogen
• For each energy level the H atom travels, a
specific photon is released
• Why?
Hydrogen
• When specific photons are emitted, we
see specific colors
• Excited Hydrogen atoms always emit
the same colors
• What does this mean?
• Hydrogen must have certain discrete
energy levels.
• This has a special name…
Hydrogen
• Quantized Energy Levels
• Energy levels of all atoms are quantized: only
certain energy level are allowed for each atom
The Bohr Model of the Atom
• Neils Bohr