Atomic Structure (INCLUDING TOF AND IONISATION ENERGY)

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  • Created by: ZoeKing98
  • Created on: 04-05-16 19:31
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  • Atomic Structure
    • Sub-atomic particles
      • Electron
        • -1 charge (relative)
        • Mass of 1/1840 (relative)
        • Found in shells/orbitals surrounding the nucleus
      • Neutron
        • 0 charge (relative)
        • Mass of 1 (relative)
        • Found by minusing atomic number from mass number
      • Proton
        • +1 charge (relative)
        • Mass of 1 (relative)
        • Found in nucleus (nucleon)
          • Neutron
            • 0 charge (relative)
            • Mass of 1 (relative)
            • Found by minusing atomic number from mass number
        • Represented by atomic number
    • Isotopes
      • Atoms of same element with varying numbers of neutrons
        • Same electron configuation
          • Same chemical properties
    • Electron shells
      • First holds up to 2 electrons
      • Second holds up to 8 electrons
      • Third holds up to 18 electrons
      • Divided into orbitals
        • s-orbital
          • spherical in shape
          • Holds up to 2 electrons
        • p-orbitals
          • Come in threes
          • Each one of the three can hold up to two electrons - 6 in total
          • Dumbell shaped
        • d-orbitals
          • Come in groups of 5
          • Shorter/fatter dumbell shaped and doughnut shaped
          • Each of five  holds up to 2 electons - 10 in total
        • Areas where the probability of finding an electron is the highest (95%)
        • Electrons fill orbitals singularly first then pair
          • Spin - the pair spin in opposite directions to overcome repulsion
    • TOF Mass Spectrometry
      • High resolution
        • Five decimal places
      • Low resolution
        • One decimal place
      • Step 1: ionisation
        • Electrospray ionisation -  sample dissolved in volatile substance and injected through hypodermic needle where the tip is attached to a positive terminal of high voltage supply, particles ionised by gaining a proton
        • Electron impact - sample vapourised an electrons fired at it from an electron gun which knocks off electrons
      • Step 2: acceleration
        • Accelarted towards a negatvey charged plate through an electric field to give all ions the same kinetc energy, lighter particles having a higher velocity and travelling faster
      • Stage 4: detection
        • Ions hit a negatively charged plate, discharged by gaining electrons and a measurable current- the size of the current determining the bumber of ions hitting the plate
      • Mass spectrum
        • Shows isotopes
        • Shows fragments
        • Peak shows relative abundance
        • Tallest and furthest far right signal - molecular ion
    • Ionisation energy (IE)
      • First ionisation: The energy required to remove a mole of electrons from one mole of atoms in gaseous state to form 1+ ions
        • Second/successive: The energy required to removed a mole of electrons from one mole of n+ ions in gaseous state to form n+1+ ions
          • Xn+(g) ------ Xn+1+(g) + e-
        • Measured in kJmol-1
          • Second/successive: The energy required to removed a mole of electrons from one mole of n+ ions in gaseous state to form n+1+ ions
            • Xn+(g) ------ Xn+1+(g) + e-
        • X(g) --------- X + (g) + e-
      • Trends
        • Across a period
          • Generally increases due to higher nuclear charge
            • Exceptions include moving to a new orbital or when electrons begin to pair within them to cause a decrease
        • Down a group
          • Generally decreases due to more sheilding and further distance from nucleus

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