Chapter 7 Atomic Structure and Periodicity - PowerPoint PPT Presentation

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Chapter 7 Atomic Structure and Periodicity

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Chapter 7 Atomic Structure and Periodicity 7.1-7.2 7.3-7.4 7.5-7.8 7.9-7.11 7.13 Properties of Light Electromagnetic radiation- the way energy travels through space. – PowerPoint PPT presentation

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Title: Chapter 7 Atomic Structure and Periodicity


1
Chapter 7Atomic Structure and Periodicity
  • 7.1-7.2
  • 7.3-7.4
  • 7.5-7.8
  • 7.9-7.11
  • 7.13

2
Properties of Light
  • Electromagnetic radiation- the way energy travels
    through space.
  • This energy travels at the speed of light.

3
Waves
  • Three characteristics
  • 1.Wavelength
  • 2.Frequency
  • 3. Speed
  • Wavelength distance between two peaks (in
    meters)
  • Frequency number of waves per second (cycles
    per second)
  • Speed travels at speed of light (meters per
    second)

4
continued
  • Inverse relationship b/t. frequency and
    wavelength.
  • Examples

5
7.2 Nature of Matter
  • Planck discovered
  • Energy is gained or lost in whole number
    quantities of hv
  • Plancks constant h 6.626 x 10-34 J.s
  • So Planck determined that energy is quantized
    (measured) in small packets called hv.

6
Energy of a Photon
  • Change in energy can be calculated by
  • Delta E nhv
  • n intergers (1,2,3)
  • h 6.626x10-34 J.s (Plancks constant)
  • v frequency of EM radiation absorbed or emitted.

7
A Photon
  • Einstein viewed electromagnetic radiation as
    travelling in a stream of particles called
    photons
  • E photon hv hc/lamda

8
To summarize.
  • Energy is quantized. It occurs in units called
    quanta.
  • Electromagnetic radiation exhibits wavelike
    properties and particulate properties also.

9
deBroglie equation
  • EM radiation shows wavelike and particulate
    properties.
  • Electrons exhibit particulate and wavelike
    properties.
  • m h/lamdav or lamda h/mv
  • Examples

10
7.3 Atomic Spectrum of Hydrogen
  • Excited hydrogen atoms emit light!
  • Hydrogen bonds are broken and H atoms release
    energy.
  • Excess energy is released by emitting light of
    different wavelengths.

11
Figure 7.7 A Change Between Two Discrete Energy
Levels Emits a Photon of Light
12
Figure 7.8 Electronic Transitions in the Bohr
Model for the Hydrogen Atom
13
Line Spectrum vs. Continuous
  • Bohr proposed that an electron orbits the nucleus
    in a rigidly defined energy level.
  • Energy Atom E photon E e-final- E e-initial

14
Continuous Spectrum
  • White light is a contiuous spectrum.
  • The Hydrogen Emission Spectrum is a LINE spectrum
  • Atoms in excited states exhibit line spectrum not
    continous spectrum.

15
Bohr model contd
  • E -2.178 x 10-18(Z2/n2)
  • Z nuclear charge
  • n the size of the radius (the larger the value
    of n, the larger the orbit radius)
  • (-) sign means energy of the electron bound to
    the nucleus is lower than if electron were at
    infinity.
  • At infinite distance, no interaction occurs and
    the energy is zero.

16
Examples
17
7.5 Quantum Mechanical Model
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