isotope

Meanings

Noun

• 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. As a consequence, atoms of isotopes will have the same atomic number but a different mass number.

Verb

• To define or demonstrate an isotopy of (one map with another).

Origin

• From iso- + -tope, because the different isotopes of a chemical element always occupy the same position in the periodic table of elements. The term was and first used publicly on February 27, 1913 by English chemist Frederick Soddy.
• Possible back-formation from isotopy.