atomic structure

• isotopes

  atoms of the same element with a different number of neutrons
• TOF: electron impact ionisation

  sample is injected into spectrometer and vapourised. high engery electrons from an electron gun are fired at the sample. the high engery electrons knock off an electron from each particle to form positive ions
• TOF: electrospray ionisation


  sample is dissolved in polar solvent and injected through a fine hypodermic needle to give a fine mist. the tip of the needle is attached to the positive terminal of a high voltage supply. particles gain a proton from the solvent to form positive ions
• TOF: acceleration

  an electric field is applied to accelerate the positive ions. this gives all the ions with the same charge the same kinetic energy
• TOF: seperation

  the positive ions travel through the mass spectrometer to the detector. the TOF of each particle depends on its velocity. lighter ions travel faster and reach the detector first, heavier ions travel slower and reach the detector last
• TOF: equation

  time of flight = distance travelled/velocity
• TOF: detection

  a decector records the different ions as they arrive at the detector. at the detector each positive ion gains an electron. this generates a current. the size of the current is proportional to the abundance of the ion. the greater the abundance, the higher the current
• mass of ion in kg

  $mass\ of\ one\ ion\ =$$\ \frac{relative\ isotopic\ mass\times10^{-3}}{6.022\times10^{23}}$
• isotopic mass

  the mass of an isotope relative to 1/12th the mass of an atom of carbon-12
• how many orbitals are in each sub-shell

  s- 1

  p- 3

  d- 5

  f-7
• how many electrons fit in a sub-shell

  2
• what order do the sub-shells fill up

  1s,2s,2p,3s,3p,4s,3d,4p
• ionisation energy

  the energy needed to remove one mole of electrons from one mole of atoms in the gaseous state