Atomic Structure

1st Shell - 2e Atomic Number = Number of Protons 2nd Shell- 8e Mass Number = Number of Protons + Number of Neutrons 3rd Shell - 18e Isotopes= Same number of Protons, Different Number of Neutrons Mass Spectrometer - Vaporisation- Make Gaseous Ionisation - Electron gun 'knocks out' electrons from the atom so the atom becomes positive Acceleration - Are attracted to negative plates, so speed up to high speeds Deflection - Magnetic field, heavier ions deflect less. Detection - Magnetic field gradually increased so each ion enters the detector consecutively

s - 2e p- 6e d- 10e f-14e Spin- 2 electrons in the same orbital must have opposite spins Ionisation energy- Energy required removing a mole of electrons from a mole of atoms in a gaseous state. E.g Sodium - Na(g) ? Na+(g) + e- First IE Na+(g) ? Na2+(g) + e- Second IE Na2+(g) ? Na3+(g) + e- Third IE

Trends - Generally 1st IE increases across a period because the nuclear charge is increasing and this makes it more difficult to remove an electron.

Anomalies - Aluminium - Outer electron in a 3p orbital which is of a slightly higher energy than the 3s orbital, therefore needs less energy to remove it. Sulfur- One of the 3p orbitals contains 2 electrons, unlike Phosphorus, which means the repulsion between the 2 electrons makes it easier to remove one of them. These cases that go against the expected trend are evidence that confirms the existence of s and p sub-levels.