gamma-radiation that produces ion
pairs carrying 1 coulomb of charge of
either sign in 1 kilogram of pure dry
air. The former unit, the roentgen
(R), is equal to 2.58 × 10
–4 C kg
–1
.
radiative capture See capture.
radical A group of atoms, either in
a compound or existing alone. See
free radical; functional group.
A
• Information about IUPAC nomenclature
• List of radical names
radical ion A radical that has a positive or negative charge. An example
is the benzene radical cation C 6 H 6
.+ .
In radical ions, the odd electron and
the charge are usually (but not necessarily) on the same atom.
radioactive age The age of an archaeological or geological specimen
as determined by a process that depends on a radioactive decay. See carbon dating; fission-track dating;
potassium–argon dating; rubidium–
strontium dating; uranium–lead
dating.
radioactive dating See radiometric dating.
radioactive isotope See radioisotope.
radioactive nuclide See radionuclide.
radioactive series A series of
radioactive nuclides in which each
member of the series is formed by
the decay of the nuclide before it.
The series ends with a stable nuclide.
Three radioactive series occur naturally, those headed by thorium–232
(thorium series), uranium–235 (actinium series), and uranium–238 (uranium series). All three series end with
an isotope of lead. The neptunium series starts with the artiÜcial isotope
plutonium–241, which decays to neptunium–237, and ends with bismuth–209.
radioactive tracing See labelling.
radioactivity The spontaneous disintegration of certain atomic nuclei
accompanied by the emission of
alpha-particles (helium nuclei), betaparticles (electrons or positrons), or
gamma radiation (short-wavelength
electromagnetic waves).
Natural radioactivity is the result of
the spontaneous disintegration of
naturally occurring radioisotopes.
Many radioisotopes can be arranged
in three *radioactive series. The rate
of disintegration is uninÛuenced by
chemical changes or any normal
changes in their environment. However, radioactivity can be induced in
many nuclides by bombarding them
with neutrons or other particles. See
also decay; ionizing radiation; radiation units.
radiocarbon dating See carbon
dating.
radiochemistry The branch of
chemistry concerned with radioactive compounds and with ionization. It includes the study of
compounds of radioactive elements
and the preparation and use of compounds containing radioactive atoms.
See labelling; radiolysis.
radiogenic Resulting from radioactive decay.
radioimmunoassay (RIA) A sensitive quantitative method for detecting trace amounts of a biomolecule,
based on its capacity to displace a radioactively labelled form of the molecule from combination with its
antibody.
radioisotope (radioactive isotope)
An isotope of an element that is
radioactive. See labelling.
radiolysis The use of ionizing radiradiative capture
452
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pairs carrying 1 coulomb of charge of
either sign in 1 kilogram of pure dry
air. The former unit, the roentgen
(R), is equal to 2.58 × 10
–4 C kg
–1
.
radiative capture See capture.
radical A group of atoms, either in
a compound or existing alone. See
free radical; functional group.
A
• Information about IUPAC nomenclature
• List of radical names
radical ion A radical that has a positive or negative charge. An example
is the benzene radical cation C 6 H 6
.+ .
In radical ions, the odd electron and
the charge are usually (but not necessarily) on the same atom.
radioactive age The age of an archaeological or geological specimen
as determined by a process that depends on a radioactive decay. See carbon dating; fission-track dating;
potassium–argon dating; rubidium–
strontium dating; uranium–lead
dating.
radioactive dating See radiometric dating.
radioactive isotope See radioisotope.
radioactive nuclide See radionuclide.
radioactive series A series of
radioactive nuclides in which each
member of the series is formed by
the decay of the nuclide before it.
The series ends with a stable nuclide.
Three radioactive series occur naturally, those headed by thorium–232
(thorium series), uranium–235 (actinium series), and uranium–238 (uranium series). All three series end with
an isotope of lead. The neptunium series starts with the artiÜcial isotope
plutonium–241, which decays to neptunium–237, and ends with bismuth–209.
radioactive tracing See labelling.
radioactivity The spontaneous disintegration of certain atomic nuclei
accompanied by the emission of
alpha-particles (helium nuclei), betaparticles (electrons or positrons), or
gamma radiation (short-wavelength
electromagnetic waves).
Natural radioactivity is the result of
the spontaneous disintegration of
naturally occurring radioisotopes.
Many radioisotopes can be arranged
in three *radioactive series. The rate
of disintegration is uninÛuenced by
chemical changes or any normal
changes in their environment. However, radioactivity can be induced in
many nuclides by bombarding them
with neutrons or other particles. See
also decay; ionizing radiation; radiation units.
radiocarbon dating See carbon
dating.
radiochemistry The branch of
chemistry concerned with radioactive compounds and with ionization. It includes the study of
compounds of radioactive elements
and the preparation and use of compounds containing radioactive atoms.
See labelling; radiolysis.
radiogenic Resulting from radioactive decay.
radioimmunoassay (RIA) A sensitive quantitative method for detecting trace amounts of a biomolecule,
based on its capacity to displace a radioactively labelled form of the molecule from combination with its
antibody.
radioisotope (radioactive isotope)
An isotope of an element that is
radioactive. See labelling.
radiolysis The use of ionizing radiradiative capture
452
r
www.AzShimi.ir www.AzShimi.com