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  • Created by: katie
  • Created on: 08-05-13 18:39

Absorption Spectra

  • white light shine through gaseous atoms
  • phontons of certain energy are absorbed by an atom
  • causing electrons to move to a higher engry level.
  • meaning light of a frequency corresponding to energy of the photon will be removed.
  • when shown on spectrometer, electronis transitions appear as dark lines against bright background.


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Emission Spectra

  • atoms given energy ( by heating or electrical field)
  • electrons are then moved to a higher energy level.
  • when source of energy removed, the elctron moves back to lower energy level.
  • QUANTUM ENERGY - packet of engry that releases the engry lost.
  • corresponds to electromagneticradiation of specific frequency.


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Hydrogen Spectrum - 1

  • Simplest emission spectrum - one electron.
  • Atomic spectrum of hydrogen - separate lines in the ultraviolet (Lyman), visible (Balmer), infrared (Paschen).


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Hydrogen Spectrum - 2

  • atom excited by absorbing energy - electron jumps to higher energy level.
  • electron falls down an enegry level - emits engry in form of electromagnetic radiation.
  • line in spectrum is emitted energy - because energy of emitted radiation equal to difference between two energy levels in this electronic transition.
  •   E=hf - electron transitions between enegry levels result in emission of radiation of different frequencies - produce different lines in spectrum.
  • Balmer series - electrons returing back to n=2 energy level. 
  • frequency increases - lines get closer together - enegry difference between the shells decrease. 
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Hydrogen Spectrum - 3

This is the hydrogen spectrum of the Balmer series:


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Ionisation of the Hydrogen Atom

  • spectral lines closer together as frequency of radiation increases until converge limit.
  • Convergence Limit - corresponds to point at which energy of an electron is no longer quantised.
  • that point, nucleus has lost all influence over the electron 
  • atom has become ionised.

measuring convergent frequency of Lyman series (difference between n=1 and n=inifinty) allows ionisation energy to be calculated using    E=hf.

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Extra Notes

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Extra Notes

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