Electron shells and Atomic Spectra

Electron shells and Atomic Spectra

1. Electrons in atoms reside in energy levels

   • shells further from nucleus have greater energy level than those closer
   • shells can only hold so many electrons
   • should be able to describe electron structure of first 36 atoms

2. Electrons absorb/release energy in fixed amounts

   • if electrons take in energy they can move to higher energy levels
   • also can release by dropping energy levels
   • energy levels all have fixed values- discrete
   • can jump between shells absorbing and releasing

3. Absorption Spectra

   • dark lines on colour
   • energy related to frequency
   • electrons only absorb certain frequencies
     • atomic absorption spectrum
     • missing freqs turn up as black bands

4. Emission Spectra

   • electrons drop to lower energy levels
     • give out energy
   • lines in same places as A spectra
   • emitted freq shows up as coloured band
   • spectrum for each element is unique

5. Energy related to frequency

   • delta E = hf
     • delta E - change in energy

6. Spectra are made up of sets of lines

   • emission- 1 set when electrons fall to n=1, another when they fall to n=2 etc
   • each spectra unique to each element
   • lines converge- energy levels get closer as freq increases

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