# isotope

/ˈaɪsəˌtoʊp/ (US) · /ˈaɪsətˌəʊp/ (UK)

Source: https://englishreference.com/word/isotope
Updated: 2026-08-27

## Senses

### 1. chemical variant

noun · CEFR C1 · Technical

a form of a chemical element that has the same number of protons but a different number of neutrons.

For teachers: any of two or more forms of a chemical element where the atoms have the same number of protons but a different number of neutrons within their nuclei.

- Carbon-14 is a famous isotope used by scientists to find the age of very old objects.
- The researchers utilized a stable isotope of nitrogen to trace the movement of nutrients through the forest ecosystem over several seasons.

Usage: Countable noun; often identified by the element name followed by the mass number.

Teaching tip: While this is a highly technical term, it is essential for students discussing archaeology, nuclear energy, or advanced biology.

## Examples

- Carbon-14 is a famous isotope used to find the age of old objects.
- Scientists analyzed the oxygen isotope ratios in the ice core to determine historical temperature fluctuations.
- The medical team utilized a specific radioactive isotope for the diagnostic scan, ensuring the tracer would decay rapidly enough to minimize the patient's overall radiation exposure.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.