Isotope Meaning
/ˈaɪ.sə.təʊp/Definition, CEFR level B2, pronunciation, examples, and quiz.
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Definition
nounAny of two or more forms of an element where the atoms have the same number of protons, but a different number of neutrons within their nuclei. Thus, isotopes have the same atomic number but a different mass number.
verbTo define or demonstrate an isotopy of (one map with another).
Sentence Examples
The principal natural isotope of aluminium is aluminium-27.
CEFR Practice Quiz
A radioactive ____ like uranium-238 decays over thousands of years.
CEFR Practice Quiz (Alternate)
Each ____ of an element has the same number of protons but a different number of neutrons in its nucleus.
Word Origin & History
From iso- (“equal”) + -tope (“place”), because the different isotopes of an element always occupy the same place in the periodic table. The term was coined by Scottish doctor Margaret Todd in 1909 and first used publicly on February 27, 1913 by English chemist Frederick Soddy.
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CEFR Practice Quiz
A radioactive ____ like uranium-238 decays over thousands of years.
CEFR Practice Quiz (Alternate)
Each ____ of an element has the same number of protons but a different number of neutrons in its nucleus.