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GCHEM question

Discussion in 'DAT Discussions' started by osimsDDS, Jun 16, 2008.

  1. osimsDDS

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    Chemistry question:

    Can someone explain energy emission vs energy absorption and how that has to do with electrons and energy levels...thanks alot
     
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  3. nixon13

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    When an electron gets excited by heat or energy and goes up energy levels (lets say from n=2 to n=3). The life time of the excited state is brief, the electrons will return rapidly to the ground state, emitting energy in the form of photons. This is the atomic emission spectra and the equation E=hc/lambda where E is the energy, h= plancks constant, c is the speed of light and lambda is the wavelength of radiation.

    Atomic Absorption spectra

    When an electron is excited to a higher energy level, it must absorb energy. The energy absorbed as en electron jumps from an orbital of lower energy to higher energy is the characteristic of that transition. So in addition to an emission spectrum, every element poses a characteristic absporption spectrum. (kinda like fingerprints for humans). This can be used to identify element present in a gas phase sample.

    Hope this helps or is what you are talking about.
     
  4. osimsDDS

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    so basically when an electron is excited it absorbs energy and then quickly goes back to its ground state emitting energy in the form of photons...and this can be exhibited through the equation E=hc/lambda

    Is this correct?? thanks
     
  5. nixon13

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    yep, do u have kaplan blue book? it is pretty straight forward in there.
     
  6. nixon13

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    Hey osims when is your DAT and what are u using to prepare? And how have your practice exams been going?
     
  7. osimsDDS

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    Mid july, ill prob go into hibernation mode in a week or so...haha
    I have taken a few kaplan biology subject tests, been getting 88% or so. Its tough but good practice. When are you taking yours?
     
  8. nixon13

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    i have it scheduled for july 7th but i wanna push it back. do u know if it costs money to reschedule?
     
  9. nixon13

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    and...i suck at zoology. What book/books are u using for taxonomy, evolution, ecology stuff?
     
  10. osimsDDS

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    i used schaum's and cliffs bio ap 3rd edition
     
  11. nixon13

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    cool i just got both.
     
  12. petra23

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    Cost is $10 to change date. Make sure you do it at least 2 business days before test
     
  13. petra23

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    $10
     
  14. DRHOYA

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    When electrons are excited to higher energy levels, it is termed absorbtion, and when they fall back down to the ground state, photons are emitted, as this is called emission. Each element has a characteristic absorbtion and emission spectra. Some things to note for emissions spectra are the Balmer and Lymman series. The Balmer series is when an electron falls within higher energy levels (n > 2 to n = 2), and the Lymman series is (n > 1 to n = 1). Hope that helps. :thumbup:

    Ps. a little fun fact. The Hydrogen atom spectra was I think the first to be characterized.
     

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