atomic structure

• VACUUM: to prevent the ions produced colliding with air air molecules
• IONISATION: the sample is forced through a fine hollow needle that is connected to the positive terminal supply which produces positive ions
• ACCELERATION: the positive ions are attracted towards a negatively charged plate and accelerated towards is.
• ION DRIFT: the electrons pass through a hole in the plate forming a beam and travelling along a tube
• DETECTION: the ions with the same charge arrive at the detector, the lighter ones are first. The positive ions pick up an electron from the detector, which causes a current flow

it detects individual ions, so different isotopes are detected separately because they have different masses. The peak height gives the relatie abundance of each isotope and the horizontal scale gives m/z which, for a slighlty charged ion is numerically the same as the mass number. 

ionisation energy is the energy required to remove one mole of electrons from a mole of atoms in gaseous state to form one mole of positive ions

• DOWN A GROUP: decreases  because electrons are further from nucleus, there is more shielding, electrons held less strongly (easier to remove)
• ACROSS A PERIOS: increases because is increased the nuclear charge that attracts electrons, electrons become harder to remove, irregularities due to the way orbitals are filled
  

 Period 3:                                                                                                                                              Magnesium to aluminium                                                                                                                 Look at their electronic configurations: Magnesium: 1s2 2s2 2p6 3s2 ... and ... aluminium: 1s2 2s2 2p6 3s2 3p1 The outer electron in aluminium is in a p sub-level. This is higher in energy than the outer electron in magnesium, which is in an s sub-level, so less energy is needed to remove it.

Phosphorus to sulphur                                                                                                                       Look at their electronic configurations: Phosphorus: 1s2 2s2 2p6 3s2 3p3 ... and ... sulphur: 1s2 2s2 2p6 3s2 3p4 It’s not immediately obvious what’s going on until we look at the arrangements of the electrons: phosphorus sulphur sub-level sub-level                                                                                                                                                         The 3p electrons in phosphorus are all unpaired. In sulphur, two of the 3p electrons are paired. There is some repulsion between paired electrons in the same sub-level. This reduces the force of their attraction to the nucleus, so less energy is needed to remove one of these paired electrons than is needed to remove an unpaired electron from phosphorus.