• Atoms contain a positively charged dense nucleus composed of protons and neutrons (nucleons).

• Negatively charged electrons occupy the space outside the nucleus.

• The mass spectrometer is used to determine the relative atomic mass of an element from its isotopic composition.

• Use of the nuclear symbol notation 𝑋𝑋 to deduce the number of protons,neutrons and electrons in atoms and ions.

• Calculations involving non-integer relative atomic masses and abundance of isotopes from given data, including mass spectra.

• Relative masses and charges of the subatomic particles should be known, actual values are given in section 4 of the data booklet. The mass of the electron can be considered negligible.

• Specific examples of isotopes need not be learned.

• The operation of the mass spectrometer is not required.