QUANTUM THEORY AND MECHANICS

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QUANTUM THEORY AND MECHANICS
Chapter 5
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What is light?

• Properties of light?
• Particles and Waves
• Light waves electromagnetic waves
• Electromagnetic radiation
• Wave Characteristics
• Amplitude
• Wavelength
• Frequency
• Speed

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Electromagnetic Radiation

• Increases in penetration, frequency, energy
• Decreases in wavelength

ROYGBIV
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Amplitude

• The height of the wave measured from the origin
  to its crest or peak.
• Determines the brightness or intensity of the
  light.
• A measure of the maximum rise or fall of a wave.
• ? meters.

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Wavelength

• The distance between successive crests of the
  wave.
• Includes one crest and one trough.
• Contains three consecutive nodes (crest to crest
  or trough to trough).
• ? meters.

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Frequency

• Tells how fast a wave oscillates up and down.
• Measured by the number of times a light wave
  completes a cycle of upward and downward motion
  in one second.
• Repetitions or cycles per second.
• ? 1/s hertz Hz.

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Velocity

• Light regardless of its wavelength moves at a
  constant speed.
• Speed of light (c) 3.00 x 108 m/s.
• Wavelength vs. Frequency
• c ? x ?
• or
• ? c / ?

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Quantum Theory DebateRutherford-Bohr models of
the atom starts the debate.

• Wave Theory
• Believe that the electron is only energy that
  moves in the form of a wave.
• They set out to calculate the energy of each
  orbit of Hydrogen from the work of Balmer.
• Max Planck Plancks Hypothesis
• Proposed quanta or small packages of energy.
• E h x n

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• Particle Theory
• Believe that the electron is only a particle that
  has mass and travels in a straight line.
• They set out to calculate the energy of each
  electron in the Hydrogen atom.
• Albert Einstein Relativity
• E mc2

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• Duality Theory
• Louie DeBroglie
• Electron is both a particle and wave (matter
  waves).
• Wavelength Plancks constant momentum

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Quantum Mechanical Atom

• Erwin Schrodinger.
• Electron exists in a cloud in regions of energy
  requirement based upon 2pr ?.
• The highest probability of finding the electron
  is closest to the nucleus.
• Heisenburg Uncertainty Principle
• The position and momentum of a moving object
  (electron) cannot be measured and known exactly.

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Quantum Mechanics

• Electron density the density of an electron
  cloud.
• Atomic orbital a region around the nucleus of an
  atom where an electron with a given energy is
  likely to be found.
• Orbitals have characteristic shapes, sizes, and
  energies.
• S (spherical), p (dumbbell), d f (more complex).

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Quantum Mechanics

• Principle energy level n.
• The energy of the electron increases as n
  increases.
• Ground state vs excited state
• Sublevels the number of sublevels in each
  principle level equals the quantum number (n).
• s, p, d, f.
• 1s, 2s, 2p, 3s, 3p, 3d, etc.

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Quantum Mechanics

• Orbitals each sublevel consists of one or more
  orbitals.
• Electrons address consists of the principle
  energy level, the sublevel, and its orbital
  within that sublevel.
• Energy comparisons between sublevels / orbitals.
• The number of orbitals increases by odd integers.
• Electron spin
• Clockwise ( ½) or Counterclockwise (- ½).
• Two electrons per orbital.

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Electron Configuration

• The distribution of electrons among the orbitals
  of an atom.
• Determined by distributing the atoms electrons
  among levels, sublevels, and orbitals based on a
  set of stated principles.
• Based on the relative energy of the orbitals.
• Ground state Electrons populate the lowest
  energy levels (most stable / can be predicted).

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Electron Configurations

• Carbon 1s22s22p2
• Sample Problems
• (pg. 135 8-9)
• Homework Problems.

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Predicting Configuration

• Figure 5-7 pg 133
• Aufbau Principle Electrons are added one at a
  time to the lowest energy orbital available.
• Pauli Exclusion Principle An orbital can hold a
  maximum of 2 electrons.
• Hunds Rule Electrons occupy equal energy
  orbitals so that a maximum number of unpaired
  electrons result.

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Orbital Diagrams

• Horizontal diagram depicting how electrons
  populate orbitals.
• Carbon 1s2 2s2 2p2
• 1s 2s 2p