1. atoms of the same element that have the same number of protons but different numbers of neutrons
Usage: chemistry; physics

Examples

• Carbon-12 and carbon-14 are isotopes of carbon.
• Radioactive isotopes are used in medical imaging.
• Scientists study isotopes to determine the age of fossils.
• Uranium has several isotopes with different atomic masses.
• The isotopes of hydrogen include deuterium and tritium.
• Nuclear power plants use specific isotopes of uranium as fuel.