Atomic Structure

Atomic Structure

PEN
1. Proton
  1. Charge = +1
  2. Relative mass = 1
2. Electron
  1. Charge = -1
  2. Relative mass = 0
3. Neutron
  1. No charge
  2. Relative mass = 1
4. Mass number = proton + neutrons
5. In atom P=E
6. Isotope
  1. Different number of neutrons
    1. same proton number
  2. Chemical properties depend on electrons
    1. Electrons arranged same in isotope so same chemical properties
    2. Physicals properties differ slightly because mass changes
Mass Spectrometer
1. VIADD
  1. Vapourisation
  2. Ionisation
    1. Electron gun fires high energy electrons
      1. But use minimum as want least 2+ ions
    2. He(g) --> He+ (g) + e-
      1. Some 2+ ions created Mg+(g) + e- --> Mg2+ (g) +2e-
  3. Acceleration
    1. Negative plates attract +ions which accelerates
  4. Deflection
    1. Electromagnet produces variable magnetic field
    2. Amount deflected depends on m/z
      1. mass/charge
        24Na+ and 48Ti2+
        Same m/z ratio 48/2 and 24/1 = 24
        So deflected by same amount
      2. Larger m/z the smaller the deflection
  5. Detection
    1. Tiny current is produced as ion takes electron from negative plante
      1. This is then amplified and sent to computer
        More currents = higher peak
        current depends on number of ions
2. m/z on x axis Abundance (usually %) on y
  1. From graph can calculate relative atomic mass (Ar)
    1. Ar=((% x m/z) + (% x m/z) +.....)/total %
    2. Ar = average mass of one atom of an element / 1/12 the mass of one carbon-12 atom
      1. Mr = average mass of one molecule/ 1/12 the mass of one carbon-12 atom
Electronic configuration
1. Orbitals
  1. 1s 2s 2p 3s 3p
    1. 4s filled befoe 3d
    2. electrons are paired with opposite spin
      1. with p and greater orbitals electrons remain unpaired filling empty orbitals first but with parallel spin
  2. Examples
    1. Na 1s2 2s2 2p6 3s1
    2. Ti 1s2 2s2 2p6 3s2 3p6 3d2 4s2
    3. Exceptions
      1. Cr 1s2 2s2 2p6 3s2 3p6 3d5 4s1
      2. Cu 1s2 2s2 2p6 3s2 3p6 3d10 4s1
2. Ionisation Energies
  1. Increases Across period 3
    1. Proton number increase
    2. Shielding stays the same
    3. Atoms become smaller as you go across
    4. Exceptions (Decreases)
      1. Aluminium - further from nucleus as it is first element with 3p electron
      2. Sulfur - first paired 3p electron so decrease due to electron-electron repulsion
  2. Decreases down Group 2
    1. More shielding as you go down (offsets proton increases)
    2. Further from nucleus
  3. Second ionisation energy always higher
    1. less shielding
    2. lost from ion
      1. Ion is smaller

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	Created by keirancorbett almost 11 years ago