# Nuclear magnetic resonance spectroscopy

> CIE A-Level Chemistry · CIE 9701 (2022 onwards)
> Source: https://www.owlsprep.com/study/cie-9701-u28-overview/
> Weight: n/a

This unit introduces 1H nuclear magnetic resonance (NMR) spectroscopy, the most powerful analytical technique for determining the full structure of unknown organic compounds in both laboratory and industrial settings.

**Prerequisites:** Basic organic molecular structure and functional group identification

## Learning objectives

- Explain the core physical principles that underpin 1H nuclear magnetic resonance spectroscopy
- Interpret 1H NMR spectra to deduce the structure of unknown organic compounds
- Relate peak properties (chemical shift, integration, splitting) to the chemical environment of protons

## 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:
- [Principles of 1H NMR](https://www.owlsprep.com/study/cie-9701-u28-principles-of-1h-nmr/) — Covers the origin of NMR signals, nuclear spin, chemical shift, and equivalent protons.
- [Interpretation of NMR spectra](https://www.owlsprep.com/study/cie-9701-u28-interpretation-of-nmr-spectra/) — Teaches use of integration, splitting patterns, and chemical shift data to deduce full organic structures.

## Common pitfalls

- **Wrong:** Mistaking solvent/reference peaks for protons in your target compound
  - Why it fails: TMS (0 ppm) and common solvents like CDCl3 (7.26 ppm) produce extra peaks that are not part of your sample
  - Correct: Always discount the TMS reference peak and note common solvent peaks before interpreting your spectrum
- **Wrong:** Confusing integration values with splitting pattern counts
  - Why it fails: Many students mix up what integration and splitting represent in an NMR spectrum
  - Correct: Integration gives the number of equivalent protons in the peak; splitting gives the number of adjacent equivalent protons

## Cheatsheet

| Key Concept | Core Summary |
| --- | --- |
| Equivalent protons | Protons in identical chemical environments produce one shared NMR peak |
| Chemical shift (δ) | Measured in ppm relative to TMS (δ=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 δ = 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.

- [Principles of 1H NMR](https://www.owlsprep.com/study/cie-9701-u28-principles-of-1h-nmr/)
- [Interpretation of NMR spectra](https://www.owlsprep.com/study/cie-9701-u28-interpretation-of-nmr-spectra/)
- [Advanced analytical techniques](https://www.owlsprep.com/study/cie-9701-u29-overview/)

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