Download Modern Atomic Theory Notes Sheet

Chemistry
Notes/Diagrams
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Modern Atomic Theory Notes
Flame Test Demo Notes/Diagrams
Observations:
Why do you think each flame was a different
color?
Additional Notes/Examples
Notetaking
Problems with Rutherford’s Atomic Theory:
 Rutherford’s atom =
 Problems:



Early 1900s:
 Scientists observed:
 What did the analysis of the emitted
light reveal?
Wave Nature of Light:
 electromagnetic(EM) radiation =
 includes:
 all EM waves travel at speed of light:
 Why do different types of EM waves have
different amounts of energy?
Wave Nature of Light Continued:
 frequency is a measure of
 high frequency waves pass through the
fixed point more often than low frequency
waves
 all electromagnetic waves travel at the
same speed:
 the electromagnetic spectrum includes
Visible Light:
 part of the electromagnetic spectrum that
we can see
 What makes up white light?
 continuous spectrum =
 Which color of light has the lowest
energy?
Which color of light has the most energy?
Light: Particle or Wave?
 Wave model of light cannot explain how
light interacts with matter

 Light as a Particle : Atomic Emission
Spectra
 every element emits EM waves of
different energy, and so produces
different colors when the emitted
light is passed through a prism
 the colors that appear are known as
the element’s:
Light as a Particle and Emission Spectra:
 Every element has a unique:
 The atomic emission spectra
phenomenon is a key piece of
evidence that light acts like a
particle
 the wave model cannot explain how
light interacts with matter
 ex: why do heated objects only
emit certain colors of light?
Max Planck:
 German physicist – 1900
 studied:
 conclusion:
 quantum =
Photoelectric Effect:
 light of certain minimum frequency causes
electrons to be ejected from the surface of
metals
 What happens if the intensity of the
light increases?
 What happens if the frequency of the
light increases?
 used in:
Photons:
 Albert Einstein in 1905 proposed:
 light is:
 What are photons?
Bohr Model of the Atom:
 What did scientists think that the
element’s atomic emission spectrums would be
like?
 What did Bohr propose for Hydrogen atoms?
 lowest state =

 What did Bohr say about Hydrogen’s single
electron?
 higher orbit =

 What do the lines of hydrogen’s
emission spectrum result from?
Energy Absorption:
 When atoms absorb energy, their electrons
become “excited” and temporarily move to a
higher energy state where they become
unstable. They must eventually return to
their lowest available energy level known as
the ground level.
Bohr Model of the Atom Continued
 Said Hydrogen’s single electron could
only be in certain allowed orbits around the
nucleus
 higher orbit =
 theorized that electrons existed in
distinct orbitals or energy levels around
the nucleus, and it took an exact amount of
energy or quanta to move an electron from
one orbital to another, which accounted for
the specific light spectra of each element
 Why was Bohr’s Model abandoned?
Electrons as Waves:
 Bohr’s model only explained Hydrogen, did
not explain the chemical behavior of all the
other elements
 Louis de Broglie – 1924
 proposed:
 derived equation that shows all
particles have wave characteristics
Heisenberg Uncertainty Principle:
 Werner Heisenberg – German physicist
 concluded:
 principle:
Schrodinger Wave Equation:
 Erwin Schrodinger – Austrian physicist 1926
 derived equation that treated hydrogen
atom’s electron as a wave
 What did his equation limit electron’s
energy to?


Quantum Mechanical Model of the Atom:
 combines de Broglie, Heisenberg, and
Schrodinger’s work into one model of the
atom
 can describe:
 calculates:
Atomic Orbitals:
 definition:
 assigned numbers:
 principal quantum number (n) =
 energy sublevels -

Four Principal Energy Levels
Principal Quantum
Number (n)
1
2
3
4
Sublevels (types of
orbitals) present
Number of orbitals
related to sublevel
Total number of
orbitals related to
principal energy level
(n2)