International Baccalaureate IB Chemistry

Atoms contain a positively charged, dense nucleus composed of protons and neutrons (nucleons). Negatively charged electrons occupy the space outside the nucleus.

Use the nuclear symbol $^{A}_{Z}\text{X}$ to deduce the number of protons, neutrons and electrons in atoms and ions. 

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

Isotopes are atoms of the same element with different numbers of neutrons.

Perform calculations involving non‑integer relative atomic masses and abundance of isotopes from given data. 

Differences in the physical properties of isotopes should be understood. Specific examples of isotopes need not be learned.

Interpret mass spectra in terms of identity and relative abundance of isotopes. The operational details of the mass spectrometer will not be assessed.