IB Chemistry - Atomic Theory

IB Chemistry home > Syllabus 2025 > Atomic theory > The mass spectrometer

Modern chemistry relies on instrumentation for analytical purposes, as results can be produced rapidly and more accurately than traditional 'wet' methods. One of the most important and powerful instruments is the mass spectrometer.

Syllabus reference

Structure 1.2.3 - Mass spectra are used to determine the relative atomic masses of elements from their isotopic composition. (HL)

  • Interpret mass spectra in terms of identity and relative abundance of isotopes.


  • The operational details of the mass spectrometer will not be assessed.

Tools and links

  • Structure 3.2 - How does the fragmentation pattern of a compound in the mass spectrometer help in the determination of its structure?

In Chapter 1.2