Spectroscopy

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Chapter 4

• Spectroscopy
• Part 1

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(No Transcript)
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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.

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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.

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Some Uses and Examples of Exciting Atoms
(Quantum Leaps)
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Aurora Borealis
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Northern lights (Auroras) are one of nature's
most beautiful manifestations of the ability of
electrons to jump between quantum states
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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.

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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.

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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.

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

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The entire article is posted near the door of the
classroom if you would like to read more.
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Star Finder Video - Fingerprints of Light (1005)
Full Video (1350)
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Homework

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