C1) Atomic structure

• Vacuum in spectrometer to stop ionised molecules hitting air molecules.
• Ionisation, Electrospray- 


  Sample dissolved in volatile solvent and forced through a small needle connected to the +ve terminal of a high voltage, solvent evaporates and leaves behind small +vely charged molecules.
• Ionisation, Electron impact-

  Sample is vaporised and high energy electrons are fired at the sample from an electron gun (hot wire filament with a current). Usually knocks off an electron- X(g) + e-  ~~~>  X+(g) + 2e-
• Acceleration-

  The +ve ions are attracted to a -vely charged plate, lighter ions are quicker as less mass slows them down.
• Ion drift- 


  Ions pass through a small hole in the plate, form a beam and travel along a tube.
• Detection-

  Ions with the same charge arrive at the detector at the same time, time is measured and current formed because ions pick up electrons from the detector which causes a current.
• Data analysis-


  The signal is passed to the computer.
• 35Cl and 37Cl are isotopes occurring in a 3:1 ratio.
• S, p, d, and f are the four orbitals.
• Order of orbitals: 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10. 4s2 loses electrons before 3d10.
• Atomic orbitals of lower energy are filled first.
• Atomic orbitals of the same energy fill singly as a pair would cause repulsion.
• First ionisation levels increase across a period and decrease down a group.
• Ionisation energy is the energy required to remove one electron from an atom.
• Ionisation of an atom increases as more get removed as the atom becomes more positive.
• Across a period:

  Increase in protons

  Increase in electrons

  Decrease in atomic radius
• Ionisation across period 2

  Boron and oxygen both dip in ionisation energy

  Boron: B lower than Be, outer electron in (2)p, higher energy than (2)s

  Oxygen: O lower than N, 2 electrons in (2)p pair together which causes repulsion, less energy needed to remove it