Elements of Life

• [Sub-atomic particles]

  Protons located in nucleus with a positive charge and a mass of 1.

  Neutrons located in nucleus with no charge and a mass of 1.

  Electrons located in shells around nucleus with a negative charge and a mass of around 0.0005.

  [Nuclear Symbols]

  Atomic Number (Z) = number of protons in nucleus

  Mass Number (A) = total number of protons and neutrons

  Isotopes are atoms of the same element with a different number of neutrons (i.e. different mass number)
• Mass spectrometry measures the atomic/ molecular mass of different particles & the relative abundances of different isotopes in a sample.

  Sample atoms or molecules are ionised, forming positively charged cations, separated according to their mass to charge (m/z) ratio, they’re detected alongside their relative abundance.