Atomic Structure

Atomic Structure

1. Fundamental particles

   • Protons
   • Neutrons
   • Electons
     • Surround a small, heavy nucleus that contains protons and neutrons

2. Mass number and isotopes

   • Mass Number
     • The total number of protons and neutrons in the nucleus of one atom of the element
   • Atomic Number
     • The number of protons in the nucleus of an atom
     • Also equal to the number of electrons in a neutral atom.
   • Isotopes
     • Atoms of the same element with the same atomic number but different mass numbers
     • Chemical properties almost identical, because chemical properties are dictate by no, electons.
     • Different physical properties e.g. rate of diffusion, boiling points

3. Mass Spectrometer

   • Used to separate ions which have nuclei of different mass. And to identify complex molecules
   • Ionisation
     • Vaporised sample, placed into the spectrometer
     • Diffuse into the path of electrons from the electron gun, and are ionised
     • Gun fires high energy electrons, which knock out an electron forming positive cations
     • M(g) + e- = M+(g) + 2e-
   • Acceleration
     • Positive ions are accelerated by an electric field
   • Deflection

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