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Mass Spectrometer
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Mass Spectrum -(Eg. Magnesium)
A sample of magnesium vapour is fed into a mass spectrometer and is bombarded by high energy electrons in the ionisation region. These electrons knock off electrons from the magnesium to produce magnesium ions (Mg+)
Mg-> Mg+ + e-
Some magnesium atoms are hit by electrons with very high energy levels so they lose 2 electrons to produce Mg2+
These charged magnesium ions are passed through the spectrometer and are sped up by an electric field- this gives all ions with the same charge the same kinetic energy. They pass through the drift region, magnesium has 3 isotopes so magnesium 24 will hit the ion detector in a shorter time then the heavier ions. The flight time will be less.
On a mass spectrum graph there would be three lines. On the y-axis is the percentage abundance in the sample and the x-axis is the mass/ charge ratio.
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- AS level Chemistry (1 Atomic Structure ) Note on Mass Spectrometer , created by Fern Bennington on 26/01/2017.
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- Fern Bennington
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