isotopes

i·so·tope   (ī'sə-tōp')    n.  One of two or more atoms having the same atomic number but different mass numbers. [iso- + Greek topos, place (so called because the isotopes of a chemical element occupy the same position in the periodic table of elements).] i'so·top'ic (-tŏp'ĭk) adj., i'so·top'i·cal·ly adv.

isotope [(eye-suh-tohp)]

In physics, different forms of the same element, with nuclei that have the same number of protons but different numbers of neutrons. Isotopes are distinguished from each other by giving the combined number of protons and neutrons in the nucleus. For example, uranium 235 is the isotope of uranium that has 235 protons and neutrons in its nucleus rather than the more commonly occurring 238. All elements have isotopes.

isotope 

Main Entry: iso·tope
Pronunciation: 'I-s&-"tOp
Function: noun
1 : any of two or more species of atoms of a chemical element with the sameatomic number and position in the periodic table and nearly identical chemical behavior but with differing atomic mass or mass number and different physical properties
2 : NUCLIDE —iso·to·pic /"I-s&-'täp-ik, -'tO-pik/ adjective —iso·to·pi·cal·ly /-'täp-i-k(&-)lE, -'tO-pi-/ adverb —iso·to·py /'I-s&-"tO-pE,I-'sät-&-pE/ noun plural -pies

isotope i·so·tope (ī'sə-tōp')
n.
One of two or more atoms having the same atomic number but different mass numbers.

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i'so·top'ic (-tŏp'ĭk) adj.