357
can be found, such as uranium-238. Small amounts of radioactive isotopes with a
short half-life are also present in nature. These isotopes are formed as a product of
the decay of larger radioactive nuclei with longer life. The atomic mass of an element in the periodic table of elements is the average of the natural distribution of
isotopes of that element.
The natural distribution of various isotopes on Earth is ultimately the result of the
amounts of isotopes formed in stars and supernovae, as well as the pattern of decay
of radioactive nuclei formed in these processes. Then, the formation of the solar
system also significantly affected the proportions of different isotopes that can be
found on Earth, because solar winds could easily blow lighter nuclei towards further
parts of the solar system immediately after the creation of the Sun. Because of this,
the large gaseous planets are farther from the Sun.
12.1.2 Stable Isotopes
Most of the chemical elements in nature are mixtures of natural isotopes, which are
either stable or radioactive (unstable). Eighty-one chemical elements have stable
isotopes. These are all elements, from hydrogen (Z = 1) to bismuth (Z = 83), with
the exception of technetium (Z = 43) and promethium (Z = 61). Many elements have
more stable isotopes, which is why their relative atomic masses are not integers.
Hydrogen is, for example, a mixture of stable isotopes
1
H and
2
H; carbon contains
stable isotopes
12
C and
13
C; oxygen contains isotopes
16
O,
17
O and
18
O and so on. Tin
has the most stable isotopes, 10 of them. In total, there are about 270 species of
stable and about 70 species of radioactive nuclides in nature (Hӧlzl et al. 2004).
Radioactive isotopes, radioisotopes (radionuclides) of individual elements, are
of natural or artificial origin. Many elements that contain stable isotopes have natural radioisotopes, as well as all-natural radioactive elements, that is, those that do
not contain stable isotopes. These are the elements from polonium to plutonium
(Z = 84–94) and the element promethium. Nuclear reactions can produce artificial
radioisotopes of almost all elements, so today about 2500 types of nuclides are
known, both natural and artificial. All of them can be classified in a nuclide map, in
which each nuclide is represented by a square with different characteristic data (isotopic abundance, half-life, type and energy of radiation). The isotopes of the individual elements are arranged in horizontal rows according to the increasing mass.
12.1.3 Unstable Isotopes
Unstable isotopes are radioactive isotopes or radionuclides and are atoms that have
a proton-neutron ratio greater or less than the ratio required for stability. Unstable
isotopes tend to be stable, and this is achieved by radioactive decay (radioactivity).
The consequences of radioactive decay are a change in the mass and/or chemical
12 Characterization of Multi-element Profiles and Multi-isotope Ratio Records as…
can be found, such as uranium-238. Small amounts of radioactive isotopes with a
short half-life are also present in nature. These isotopes are formed as a product of
the decay of larger radioactive nuclei with longer life. The atomic mass of an element in the periodic table of elements is the average of the natural distribution of
isotopes of that element.
The natural distribution of various isotopes on Earth is ultimately the result of the
amounts of isotopes formed in stars and supernovae, as well as the pattern of decay
of radioactive nuclei formed in these processes. Then, the formation of the solar
system also significantly affected the proportions of different isotopes that can be
found on Earth, because solar winds could easily blow lighter nuclei towards further
parts of the solar system immediately after the creation of the Sun. Because of this,
the large gaseous planets are farther from the Sun.
12.1.2 Stable Isotopes
Most of the chemical elements in nature are mixtures of natural isotopes, which are
either stable or radioactive (unstable). Eighty-one chemical elements have stable
isotopes. These are all elements, from hydrogen (Z = 1) to bismuth (Z = 83), with
the exception of technetium (Z = 43) and promethium (Z = 61). Many elements have
more stable isotopes, which is why their relative atomic masses are not integers.
Hydrogen is, for example, a mixture of stable isotopes
1
H and
2
H; carbon contains
stable isotopes
12
C and
13
C; oxygen contains isotopes
16
O,
17
O and
18
O and so on. Tin
has the most stable isotopes, 10 of them. In total, there are about 270 species of
stable and about 70 species of radioactive nuclides in nature (Hӧlzl et al. 2004).
Radioactive isotopes, radioisotopes (radionuclides) of individual elements, are
of natural or artificial origin. Many elements that contain stable isotopes have natural radioisotopes, as well as all-natural radioactive elements, that is, those that do
not contain stable isotopes. These are the elements from polonium to plutonium
(Z = 84–94) and the element promethium. Nuclear reactions can produce artificial
radioisotopes of almost all elements, so today about 2500 types of nuclides are
known, both natural and artificial. All of them can be classified in a nuclide map, in
which each nuclide is represented by a square with different characteristic data (isotopic abundance, half-life, type and energy of radiation). The isotopes of the individual elements are arranged in horizontal rows according to the increasing mass.
12.1.3 Unstable Isotopes
Unstable isotopes are radioactive isotopes or radionuclides and are atoms that have
a proton-neutron ratio greater or less than the ratio required for stability. Unstable
isotopes tend to be stable, and this is achieved by radioactive decay (radioactivity).
The consequences of radioactive decay are a change in the mass and/or chemical
12 Characterization of Multi-element Profiles and Multi-isotope Ratio Records as…