Topic 2: Atomic structure - 2.1 The nuclear atom

Nature of science: Evidence and improvements in instrumentation-alpha particles were used in the development of the nuclear model of the atom that was first proposed by Rutherford. (1.8). Paradigm shifts-the subatomic particle theory of matter represents a paradigm shift in science that occurred in the late 1800s. (2.3)


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.

Applications and skills

Use of the nuclear symbol notation AZX 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.