Chemistry AS (1)

Chem 1

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  • Created by: emily
  • Created on: 19-12-11 09:55

Atomic structure -atoms

atoms are made up from sub-atomic particles:

Proton -relative charge:+1

   - relative mass: 1

Neutron -relative charge: 0

      -relative mass: 1

Electron -relative charge: -1

       -relative mass:1/1836

Isotopes of the same element will have the same proton number but a diffrent number of neutrons.  Meaning that diffrent isotopes are chemicially identical as they have the same electron configuration however they are physically diffrent.

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Atomic structure -mass spectrometer

Mass spec. a machine that can analyse samples of elements to find the abundance of isotopes. There are 5 main stages in the mass spec:

Vaporization- the sample needs to be vaporized so that it can pass through the mass spec                                                                                                          Ionization- the vaporized sample needs to be ionized so that it can be 1)accelerated through the mass spec. 2)be detected. A stream of high energy electrons are produced by an electron gun and hit the atoms in the sample to knock off  an electron meaning they become ions with single posative charges        Acceleration- the sample is accelerated through the mass spec. by an electric field.  this 1)focusses the sample into a narrow beam 2)causes the sample to move very quickly                                                                                                  Deflection- the sample is deflected by elecrtomagnets, The force deflected by the size of the charge on the ion, lighter ions will be deflected more than heavier ions                                                                                                                  Detection- due to the sample being ionized it will cause a tiny current when hitting a negative plate, the more ions the bigger the current. this is then recorded on a mass spectrum.

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