Unit Overview
Nuclear magnetic resonance spectroscopy
CIE A-Level ChemistryΒ· 5 min read π n/a
1. Unit at a Glance
This unit builds progressively from core theory to practical, exam-focused skills. You will first learn how NMR signals arise from proton nuclear spin and how the chemical environment of a proton alters its signal position. You will then apply this knowledge to interpret full NMR spectra and solve unknown organic structures, the key skill assessed for this topic.
This unit contains two core sub-topics:
2. Common Pitfalls
Wrong move:
Mistaking solvent/reference peaks for protons in your target compound
Why:
TMS (0 ppm) and common solvents like CDCl3 (7.26 ppm) produce extra peaks that are not part of your sample
Correct move:
Always discount the TMS reference peak and note common solvent peaks before interpreting your spectrum
Wrong move:
Confusing integration values with splitting pattern counts
Why:
Many students mix up what integration and splitting represent in an NMR spectrum
Correct move:
Integration gives the number of equivalent protons in the peak; splitting gives the number of adjacent equivalent protons
3. Quick Reference Cheatsheet
Key Concept | Core Summary |
|---|---|
Equivalent protons | Protons in identical chemical environments produce one shared NMR peak |
Chemical shift (Ξ΄) | Measured in ppm relative to TMS (Ξ΄=0), indicates electron density around a proton |
Integration | Peak area is proportional to the number of protons producing the peak |
n+1 Rule | Splitting of a peak = n + 1, where n = number of equivalent adjacent protons |
TMS Reference | Tetramethylsilane is used as a standard reference, defined as Ξ΄ = 0 ppm |
What's Next
Begin with the first sub-topic to master the core principles of 1H NMR before moving on to spectrum interpretation, the key assessed skill for this unit. Once you complete both sub-topics in this unit, you can progress to the next topic covering other analytical separation techniques.