isotope
UK /ˈaɪ.sə.təʊp/ · US /ˈaɪ.sə.toʊp/ noun, verb
Forms isotopes isotoping isotoped
- noun (nuclear physics) Any 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.
- verb (topology, transitive) To define or demonstrate an isotopy of (one map with another).
Etymology
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.
Possible back-formation from isotopy.
Sources: Wiktionary — from the Wiktionary entry “isotope”, CC BY-SA 4.0. Details