5'1 Light and Quantized Energy

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5.1 Light and Quantized Energy
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Rutherfords Model

• Pros
• virtually all mass in nucleus
• e-s surround
• major scientific development
• Cons
• how do the e-s occupy the space?
• why were they not pulled into the atoms
  positively charged nucleus?

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Additional discovery

• Scientists also noticed elements emitted visible
  light when heated
• This is due to the arrangement of the electrons

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Basic Atom Stuff

• E- negative charge, move around outside of
  nucleus
• P positive charge in nucleus
• Why dont they attract?
• Has to do with ENERGY!
• The energy of motion of the e-s prevent them
  from being pulled in!

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EM Radiation

• Form of energy that behaves like waves as it
  moves
• Examples
• Visible light
• Microwaves
• X rays
• Radio waves

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Looking at the waves

• Different waves have different frequencies
• Different wiggles produce different ?s
• Different ?s correspond with specific parts of
  the EM spectrum
• Visible light is a very SMALL part of the EM
  spectrum

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Particle Nature of Light

• When an element is exposed to NRG, the e-s
  inside the atom directly absorb that NRG
• The amount is called a quantam
• When e-s absorb NRG with a certain quantum, they
  become excited
• Excitement released as visible light

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Wiggle it.Just a little bit

• Heating elements cause their e-s to wiggle
  faster
• Affects the frequency (increases) AND the color
  of visible light
• Scientists passed this light through a prism

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• They expected to see the rainbow of colors
• This is called a continuous spectrum
• But you dont always get what you want ?
• They saw just certain lines of color
• So when some elements are heated, and the light
  is passed through the prism, only ONE color may
  be seen
• You see a DISCONTINUOUS band of colors known as
  the ATOMIC EMISSION SPECTRUM

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Atomic Emission Spectrum

• Called this because it is the visible range of
  colors in the EM spectrum that an atom of that
  element emits
• The closer the bands, the HIGHER the frequency
  and the HIGHER the energy
• Farther, less frequent, lower energy
• Each line represents a ? in e- energy dependent
  of quantum of energy absorbed and emitted

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Elemental Fingerprinting

• Each element gives off specific spectral lines
• No 2 elements have the same atomic emission
  spectrum!
• This fingerprinting technique is called
  spectroscopy
• We can examine spectral lines from distant stars
  to determine composition

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Red Shift?