Isotope
Part of speech: noun
Definition: 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 thier nuclei. As a consequence, atoms for the same isotope will have the same atomic number but a different mass number (atomic weight).
Part of speech: verb
Definition: To define or demonstrate an isotopy of (one map with another).
Isomer
Part of speech: noun
Definition: Any of two or more compounds with the same molecular formula but with different structure.Any of two or more atomic nuclei with the same mass number and atomic number but with different radioactive properties.