Quantum Mechanical Atom Part I: Electromagnetic Radiation Chapter 8 Section 1 - PowerPoint PPT Presentation

Loading...

PPT – Quantum Mechanical Atom Part I: Electromagnetic Radiation Chapter 8 Section 1 PowerPoint presentation | free to download - id: 573b1b-NDRlN



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Quantum Mechanical Atom Part I: Electromagnetic Radiation Chapter 8 Section 1

Description:

Quantum Mechanical Atom Part I: Electromagnetic Radiation Chapter 8 Section 1 & 2 of Jespersen 6th ed) Dr. C. Yau Spring 2013 * * Electromagnetic Radiation ... – PowerPoint PPT presentation

Number of Views:159
Avg rating:3.0/5.0
Slides: 18
Provided by: C440
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Quantum Mechanical Atom Part I: Electromagnetic Radiation Chapter 8 Section 1


1
Quantum Mechanical Atom Part I Electromagnetic
Radiation Chapter 8 Section 1 2 of Jespersen
6th ed)
  • Dr. C. Yau
  • Spring 2013

2
Electromagnetic Radiation
  • Electromagnetic radiation carries E thru space by
    means of a wave.
  • Properties of a wave (Refer to lec. Notes)
  • Wavelength (?, pronounced lambda)
  • Frequency (?, pronounced nu)
  • Amplitude (A)
  • Energy of the photon (uniform packets of E,
    proportional to frequency)

3
Units of Measurement
  • Wavelength m, cm, ?m, nm,
  • angstrom Å
  • 1 nm 10 Å
  • 1 m 1010 Å
  • Frequency cycles per second 1/sec sec-1
  • 1 Hertz 1 Hz 1 sec-1
  • Energy J, kJ, ergs

4
How are they related?
? x ? c 2.998x108 m s-1 (speed of light) ? is
inversely proportional to ? Example 8.1 p.
253 Mycobacterium tuberculosis, the organism that
causes tuberculosis, can be completely destroyed
by irradiation with UV light with a wavelength of
254 nm. What is the frequency of this radiation?
5
Example 8.2 p. 308
Radio station WKXR is an AM radio station
broadcasting from Asheboro, N Carolina, at a
frequency of 1260 kHz. What is the wavelength of
these radio waves expressed in meters? Do
Pract Exer 1, 2, 3 p.308
6
Energy of a Light Wave
  • The energy carried by a light wave is said to be
    in discrete packets called "photons."
  • Size of energy of the photons is proportional to
    the frequency of the wave.
  • E h ?
  • where h Planck's constant
  • 6.626x10-34 J s
  • You dont need to memorize constants.

7
Relationship between wavelength, frequency
energy of the photon
8
The Rainbow
  • The rainbow is a small region of the
    electromagnetic radiation spectrum, the visible
    region of the spectrum.
  • You should know the names of the rest of the
    regions of the spectrum, and in order of energy,
    frequency and wavelength. (See lecture notes.)

9
Electromagnetic Radiation Spectrum
  • Fig. 8.3 p. 310

10
Absorption of light by chlorophyll
11
What is the energy of a photon of the red light
at 700. nm?
  • What do we know about energy and the wave?
  • How is wavelength related to frequency?
  • How is energy related to wavelength?

12
Continuous vs. Line Spectrum
  • What do we see if ordinary white light is passed
    through a prism?
  • If we pass a current through a partially
    evacuated tube of a gas, a light is emitted.
  • If this emitted light is passed through a prism,
    we do not see a continuous rainbow, instead we
    see...

13
Figure 8.7 p. 314 Emission Line Spectrum
We see discrete colored lines on a black
background
14
Line Spectra are like fingerprints
15
Line Spectrum of H2
  • A mathematician came up with an equation that
    describes the pattern of lines observed for
    hydrogen (the Rydberg Eqn).
  • The equation does not EXPLAIN why there is such a
    pattern.
  • Bohr came up with his Planetary Model of the Atom
    that EXPLAINS why hydrogen would produce such a
    pattern of lines.
  • (See lecture notes.)

16
Bohr's Calculations
  • Each emission line of hydrogen is due to the
    energy released in the transition of an electron
    from a higher E level to a lower one.
  • Bohr's equation En ? B/n2
  • Bohr's constant, B 2.180x10-18 J
  • This allows us to calculate the E of each level.
  • The amount of E released is equal to ?E.
  • ?E Ehi Elo
  • Once we have calculated ?E, we can determine the
    corresponding ? and ?.
  • (See lecture notes.)

17
Why Schroedinger has to come up with a different
model
  • Bohrs theory could predict emission lines for
    one electron system ONLY.
  • What are one-electron systems?
  • How is Schroedingers model different from
    Bohrs?
  • See next PowerPoint.
About PowerShow.com