Electronic Structure of Atoms: Chapter 6, Sections 1-4

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Electronic Structure of Atoms Chapter 6,
Sections 1-4
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6.1 The Wave Nature of Light

• Electronic structure describes energies and
  arrangement of electrons around .
• Electromagnetic radiation radiant energy
  carries energy through space it moves through
  a vacuum at the speed of light (3 x 108 m/s).
• It has electric and magnetic components that are
  in a wave-like structure.

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6.1 The Wave Nature of Light

• Waves are described in terms of
• Wavelength ? distance between peaks
• Frequency ? periods per unit time
• v ?c c speed of light

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6.2 Quantized Energy and Photons

• The minimum amount of radiant energy that an
  object can gain or lose is related to the
  frequency of the radiation Ehv.
• Plancks constant h6.63 x 10-34 J-s.
• Energy is quantized, meaning it can only have
  certain allowed values.
• Einstein proposed that that light behaves as if
  it consisted of quantized energy packets called
  photons. Each photon carries energy, Ehv.

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6.3 Bohrs Model of the Hydrogen Atom

• Spectrum produced by dispersion of radiation
  into its component wavelengths.
• Continuous spectrum contains all wavelengths.
• Line spectrum contains only certain wavelengths.
  
• En represents the energy of the hydrogen atom.
  (n) is the principal quantum number and the
  energy of the atom increases as n increases.

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6.3 Bohrs Model of the Hydrogen Atom

• Use the following equation to relate the
  frequency of absorbed or emitted light and the
  principal quantum numbers of the two states.
• ?E Rh 1 - 1
• v h h n2i n2f
• Rh is known as Rhydbergs constant
• 2.18 x 10-18 J
• h is Plancks constant
• 6.63 x 10 -34 Js

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Wavelength to frequency

• _c_
• ? v
• Be careful that you convert from nm or Angstroms
  to meters so that you units match.

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6.3 Bohrs Model of the Hydrogen Atom

• The lowest energy level is achieved in the ground
  state where n1.
• Other n values correspond to excited states.
• Light is emitted when the electron drops from a
  high energy state to a low energy state light
  can be absorbed to excite the electron from a low
  energy state to a high energy state.
• The frequency of light emitted or absorbed must
  be such that hvthe difference in energy between
  two allowed states of the atom.

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6.4 The Wave Behavior of Matter

• Radiation appears to have either a wavelike or a
  particle-like (photon) character
• Louis De Broglie (1892-1987) suggested that the
  electron in its movement about the nucleus has
  associated with it a particular wavelength
• De Broglie proposed that wavelength of an
  electron depends on its mass and velocity
• ? h/mv wavelength Plancks constant/ momentum
  (mass x velocity)
• De Broglie used the term matter waves to describe
  the wave characteristics of material particles

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6.4 The Wave Behavior of Matter

• German physicist Werner Heisenburg concluded that
  the dual nature of matter places a fundamental
  limitation on how precisely we can know both the
  location and the momentum of any object
• Heisenburgs principle is called the uncertainty
  principle which states that it is inherently
  impossible for us to know simultaneously both the
  exact momentum of an electron and its exact
  location in space

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Thanks to

• Alex Kawa, Kate Harkness, Will Lambert, Adam
  Robinson, Tori Waldron, Ankush Khullar