2_Atomic Structure

2_Atomic Structure

1. Mass, Atomic Number and Particles

   • Atomic Number = Proton Number = Z
   • Mass Number = Number of Protons and Neurtrons = A
   • Isotopes
     • Same number of protons, different number of neutrons
     • React the same chemically
     • Vary in mass number

2. Mass Spectrometer

   • 1. Gaseous state
   • 2. Ionisation - beam of electrons from an electron gun knocks electrons to make positive ions
   • 3. Acceleration - positive ions are attracted towards negatively charged plates and are accelerated the lighter the ions the faster they go , they pass through slits in the plates forming a beam
   • 4. Deflection - beam moves into a magnetic field which deflects them into an arc (m/z dependant) heavier ions are deflected less
   • 5. Detection - magnetic field is gradually increased so ions with increasing mass enter the detector creating a current proportional to their abundance

3. Electron arrangement

   • 1S, 2S, 2P, 3S, 3P, 3D, 4S etc
   • 2 electrons in s orbital, 6 in p orbital, 10 in d orbital and 14 in f orbital

4. Ionisation energy

   • the energy required to remove one mole of electrons from one mole of atoms in the gaseous state
   • General increace across periods because nuclear charge increaces
   • decreace down periods because the outer electron is further away from the nucleus