# Dalton

/ˈdɔɫtən/ (US)

Source: https://englishreference.com/word/dalton
Updated: 2026-08-15

## Senses

### 1. unit of atomic mass

noun · CEFR C1 · Technical

a tiny unit of weight used to measure atoms and molecules.

For teachers: a unit of mass used to express atomic and molecular weights, numerically equivalent to the unified atomic mass unit.

- The scientist explained that the protein has a mass of 50,000 daltons.
- The molecular weight of the newly synthesised compound was determined to be approximately 450 daltons using mass spectrometry.

Usage: Often abbreviated as 'Da' and used with metric prefixes like kilodalton (kDa).

Teaching tip: This is a highly specialised term; outside of biochemistry or physics, students will rarely encounter it.

## Examples

- The atomic mass of oxygen is about 16 daltons.
- Scientists measure the size of large proteins in daltons to understand their structure.

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