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isotope
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Isotope
One of two or more atoms that have the same atomic number (same number of protons), but which contain a different number of neutrons, thus differing in their relative atomic mass. They may be stable or radioactive (as a radioisotope), naturally occurring, or synthesized. For example, hydrogen has the isotopes 2H (deuterium) and 3H (tritium). The term was coined by English chemist Frederick Soddy, a pioneer researcher in atomic disintegration.
Elements at the lower end of the periodic table have atoms with roughly the same number of protons as neutrons. These elements are called stable isotopes. The stable isotopes of oxygen include 16O, 17O, and 18O; those of carbon include 12C and 14C. Elements with high atomic mass numbers have many more neutrons than protons and are therefore less stable. It is these isotopes that are more prone to radioactive decay. Examples are 238U (uranium-238) and 60Co (cobalt-60).
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alpha particle
atom
atom, electronic structure of
atomic number
atomic structure
background radiation
beta particle
electric charge
electron
fission
formula (chemistry)
fusion (physics)
gamma radiation
Geiger counter
Geiger–Müller tube
half-life
ion
ionizing radiation
isotope
mass number
molecular formula
molecule
neutron
nucleus (physics)
octet rule
proton
radiation
radioactivity
radioisotope
relative molecular mass
valence
valence shell
atom
atom, electronic structure of
atomic number
atomic structure
background radiation
beta particle
electric charge
electron
fission
formula (chemistry)
fusion (physics)
gamma radiation
Geiger counter
Geiger–Müller tube
half-life
ion
ionizing radiation
isotope
mass number
molecular formula
molecule
neutron
nucleus (physics)
octet rule
proton
radiation
radioactivity
radioisotope
relative molecular mass
valence
valence shell
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