10. How We Use EM Spectrum for Spectroscopy
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17 Terms
Give a summary of atomic spectroscopy
Movement of electrons from low to high energy levels (or vice versa) cause spectroscopic excitations
What can spectroscopic excitations be used for?
To work out energy gaps between subshells and orbitals
How can atomic spectroscopy be carried out?
Absorption and Emission
What does absorption spectroscopy do?
Measures light energy absorbed
How is absorption spectroscopy carried out?
Beam of white light passes through gaseous sample of element, photons of certain energy may be absorbed by atom causing electron to move from lower to higher energy level
What does absorption spectroscopy looked like?
When light is examined by spectrometer, electronic transitions appear as dark lines against bright background
What does this mean (following off how absorption spectroscopy is carried out)?
This means that light of a frequency corresponding to energy of photon will be removed
What does emission spectroscopy do?
Measures light emitted
Describe how emission spectroscopy is the opposite to absorption spectroscopy?
Measures frequency emitted when excited electron falls to ground state when energy source removed
How are electrons released in emission spectroscopy?
e- released as photons of light -> higher energy = larger transmission
What does emission spectrum consist of?
Series of sharp lines
Why does emission spectrum consist of a series of sharp lines?
Because energy levels in atom are quantised so only certain energy transitions are possible
How is emission spectrum not a continuous spectrum?
Because it has sharp lines whilst continuous spectrum has all colours of the rainbow
What happens to lines on emission spectrum?
Converge as energy increases (get closer together until they merge at convergence limit)
What is the convergence limit?
The point in the emission spectrum where separate lines cannot be distinguished at n = infinity
What happens at the convergence limit?
Atom is ionised
What is n=1?
The ground state