A :B :C :D :E :F :G :H :I :J :K :L :M :N :O :P :Q :R :S :T :U :V :W :X :Y :Z :


Isotope

One of two or more atoms or elements which have the same atomic number (occupy the same position in the periodic table) but which differ in other respects such as atomic weight and number of neutrons in the nucleus.