noun
isotope
EYE-suh-tohp
noun
1
One of two or more versions of a chemical element that have the same number of protons but a different number of neutrons.
"Carbon-14 is a radioactive isotope used to date ancient bones."
"Uranium has several isotopes, some far more unstable than others."
How to Use Isotope
Learner’s notesIn plain EnglishA variant of a chemical element that has extra or fewer neutrons in its atoms, but the same number of protons.
Common pairings
radioactive isotope
stable isotope
Word Forms
isotoped past tense, isotopes plural, isotopes singular
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Carbon-14 is a radioactive _____ used to date ancient bones.
Etymology
From Greek iso- ("same") plus -tope ("place"), because isotopes occupy the same position in the periodic table. Coined in 1913 by chemist Frederick Soddy, building on a suggestion by physician Margaret Todd in 1909.