Atomic Structure

Fundamental particles

• Nucleus of atom contains protons and neutrons
• Electrons surround nucleus in orbitals
• Relative masses:
  • Proton- 1
  • Neutron- 1
  • Electron- 1/1840
• Relative charges:
  • Proton- +1
  • Neutron- 0
  • Electron- -1

Mass number and isotopes

• Atomic number (Z)- number of protons in nucleus of atom
• Mass number (A)- total number of protons and neutrons in nucleus of atom
• Isotopes- atoms with the same number of protons but different numbers of neutrons
  • Same chemical properties- same electron configuration
• TOF Mass Spectrometer
  • High vacuum- prevents ions produced from colliding with particles in air
  • Electrospray ionisation: 
    • Sample dissolved in volatile solvent
    • Forced through fine hollow needle connected to positive terminal of high voltage supply
    • Produces tiny positively charged droplets- gained proton from solvent
    • Solvent evaporates, leaving single positive ions
  • Electron impact:
    • Sample vaporised
    • High energy electrons fired at it from electron gun
    • Electron gun: hot wire filament with current running through it…