Isotope
/ˈaɪ.sə.toʊp/noun
An atom of an element with the same number of protons as other atoms of that element but a different number of neutrons.
Did you know?The term was coined by radiochemist Margaret Todd in 1913 at Frederick Soddy’s suggestion, and Soddy later won the Nobel Prize for isotope research.
Etymological Timeline
Ancient Greek
Greek
isos
“equal or same”
Ancient Greek
Greek
topos
“place or location”
19th Century
Greek-derived scientific vocabulary
iso-
“A combining form meaning equal or identical”
1913
English
isotope
“A term coined for atoms of the same element occupying the same position in the periodic table”
20th Century
Modern scientific English
isotope
“One of multiple atomic forms of an element differing in neutron number and atomic mass”