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Spectroscopy

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Title: Spectroscopy


1
Chapter 4
  • Spectroscopy
  • Parts 1 2

2
(No Transcript)
3
Describe the process that occurs inside atoms
that produces the spectra?
  • Energy is absorbed by the atom.
  • The electrons jump into higher orbits and the
    atom becomes excited.
  • The electrons return to their original orbits and
    the atom returns to the ground state.
  • The electrons release energy in the form of
    visible light.
  • Each quantum leap produces a specific spectral
    line of a certain energy (wavelength, frequency)
    of visible light.

4
Quantum Leaps
  • A quantum leap is a change of an electron from
    one energy state to another within an atom.
  • Quantum leaps cause the absorption and emission
    of electromagnetic radiation in which excited
    atoms release small packets of electromagnetic
    energy called photons.

5
Some Uses and Examples of Exciting Atoms
(Quantum Leaps)
6
Aurora Borealis
7
Northern lights (Auroras) are one of nature's
most beautiful manifestations of the ability of
electrons to jump between quantum states
8
What Causes the Aurora
  • High speed energetic particles collide with atoms
    in Earth's atmosphere to cause the aurora. These
    high speed particles, which are usually
    electrons, originate from space, specifically
    from the solar wind, blowing outward from the
    Sun.
  • When the electrons from space strike an atom or
    molecule in Earth's atmosphere, they give one of
    the electrons in the atom an energy boost. In
    scientific jargon, the electron jumps to a higher
    energy level and the atom is in an excited state.

9
What Causes the Aurora
  • After a while, the electron in the excited atom
    jumps back down to its original lower energy
    level. It releases this energy as light causing
    the auroral glow. This process is the same
    mechanism that causes emission line spectra and
    aurora are in fact emission line spectra of the
    atoms in Earth's upper atmosphere.
  • The color of emission line spectra depends on the
    type of atom that is excited, and each type of
    atom produces its own unique pattern of colors.
    Hence, the different colors in auroral displays
    originate from different elements in Earth's
    atmosphere.

10
What Causes the Aurora
  • Oxygen molecules cause the green Aurora, and
    oxygen atoms cause the red colors. Blue auroral
    displays result from nitrogen molecules.
    Molecular nitrogen and oxygen are the most common
    constituents of Earth's atmosphere, so these are
    the most common auroral colors. Mixtures of these
    colors form the other colors of the auroras.

11
Northern Lights Video (357)
12
  • Did you ever wonder how we know what the universe
    is made of?

13
The entire article is posted near the door of the
classroom if you would like to read more.
14
Star Finder Video - Fingerprints of Light (1005)
Full Video (1350)
15
  • Spectroscopy is the study of the energy which is
    given off and absorbed when atoms go from the
    ground state to the excited state and back again.
  • Spectroscopy is often used in chemistry for the
    identification of substances, through the
    spectrum absorbed or emitted.

16
Spectroscope
17
Fireworks
18
Neon Signs
19
Light Sources Mercury
  • CFLs
  • The average rated life of a CFL is between 8 and
    15 times that of incandescents. CFLs typically
    have a rated lifespan of between 6,000 and 15,000
    hours, whereas incandescent lamps are usually
    manufactured to have a lifespan of 750 hours or
    1,000 hours.

Mercury Vapor Lamp
20
  • Spectrum of a CFL bulb. The camera had a
    diffraction grating in front of the lens. The
    discrete images are produced by the different
    colors in the light, a line spectrum. An
    incandescent lamp would instead have a
    continuous band of color.

21
American and 2 Japanese Physicists Share 2014
Nobel Prize for Work on LED Lights
22
LEDs
  • LEDs, (Light emitting diodes), are found in all
    kinds of devices.
  • They form numbers on digital clocks, transmit
    information from remote controls, light up
    watches.
  • Collected together, they form the illuminated
    screens on cell phones and television screens.
  • Basically, LEDs are just tiny light bulbs that
    fit easily into an electrical circuit. But unlike
    ordinary incandescent bulbs, they don't have a
    filament that will burn out, and they don't get
    especially hot.

23
LEDs
  • LEDs are illuminated solely by the movement of
    electrons.
  • The lifespan of an LED is impressive lasting 10
    times as long as a fluorescent bulb and 100 times
    as long as an incandescent bulb.
  • LED bulbs do not have toxic mercury as do CFLs.
  • Due to low power requirements, it can be powered
    by cheap local solar power. Thus bringing the
    advantage of electrical devices to places that
    lack electrical power grids.
  • Currently upfront costs are higher than many
    consumers which to pay but costs are continuing
    to drop as technology improves.

24
  • In the future, some of the most incredible uses
    of LEDs will actually come from organic light
    emitting diodes, or OLEDs which are flexible,
    allowing scientists to create bendable lights and
    displays. (Imagine rolling your TV up like a
    poster and carrying it with you anywhere).

25
Lasers
  • You'll find them in everything from CD players to
    dental drills to high-speed metal cutting
    machines to measuring systems. Tattoo removal,
    hair replacement, eye surgery -- they all use
    lasers.

26
What else can lasers be used for?
  • Sharks

27
I want sharks with laser beams attached to their
heads.
28
Flame Tests
29
Flame Tests
  • A flame test is a procedure used in chemistry to
    detect the presence of certain metal ions based
    on each element's characteristic emission
    spectrum.

30
..\..\..\..\Videos\Flame Tests.wmv
Video Flame Tests (27seconds)
31
Video Molecular Fingerprints (15
min.)Worksheet is in notebook.
  • ..\..\..\..\Videos\World of Chemistry\Molecular
    Fingerprints.mpg

32
Homework
  • Summarize the purpose and procedure for the
    Flame Test Lab (Due tomorrow).
  • Chapter 4 Worksheet 3 (Due Friday).
  • Study Guide Chapter 4 (Due Friday).
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