Synthetic element
Encyclopedia
In chemistry, a synthetic element is a chemical element
that is too unstable to occur naturally on Earth
, and therefore has to be created artificially. So far 30 synthetic elements have been discovered—that is, synthesized. Six of them are "quasi-synthetic"—meaning that they occur naturally on Earth in trace quantities and generally have to be produced artificially,—and 24 are "fully synthetic"—meaning that they do not occur naturally on Earth at all, and can only be produced artificially. Of all the synthetic elements, plutonium
—first synthesized in 1940—is the one best known to lay people, because of its use in atomic bombs and nuclear reactor
s.
very rapidly into lighter elements—possessing half-live
s so short, relative to the age of the Earth (which formed 4.54 billion years ago), that any atom
s of these elements that may have existed when the Earth formed have long since decayed. Because of this, atoms of synthetic elements only occur on Earth as the product of experiments that involve nuclear reactor
s or particle accelerator
s, via nuclear fusion
or neutron absorption.
Atomic mass
for natural life is based on weighted average abundance of natural isotopes that occur in the Earth's crust and atmosphere. For synthetic elements, the isotope depends on the means of synthesis, so the concept of natural isotope abundance has no meaning. Therefore, for synthetic elements the total nucleus
count (proton
s plus neutron
s) of the most stable isotope—i.e., the isotope with the longest half-life—is listed in brackets as the atomic mass.
(Note: Just because an element is radioactive does not mean it is synthetic. For instance, uranium
and thorium
have no stable isotopes but occur naturally in the Earth's crust and atmosphere; therefore, neither are synthetic. Unstable elements such as polonium
, radium
, and radon
—which form through the decay of uranium and thorium—are also found in nature, despite their short half-lives.)
—its discovery being definitely confirmed in 1936. This discovery filled a gap in the periodic table
, and the fact that no stable isotope
s of technetium exist explains its natural absence on Earth (and the gap). With the longest-lived isotope of technetium, Tc-98, having a 4.2 million year half-life, no technetium remains from the formation of the Earth. Only minute traces of technetium occur naturally in the Earth's crust—as a spontaneous fission product
of uranium-238 or by neutron capture
in molybdenum
ores—but technetium is present naturally in red giant
stars.
s 1 through 94, including these, are naturally occurring at least in trace quantities.
Transuranium element
Transfermium element
Transactinide element
(* The United States
and Soviet Union
made discoveries of Dubnium independently and were given shared credit by IUPAC/IUPAP in 1992. In 1997, IUPAC decided to give the element its current name—a name suggested by the Russians—since American-chosen names had already been used for many existing synthetic elements.)
Chemical element
A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Familiar examples of elements include carbon, oxygen, aluminum, iron, copper, gold, mercury, and lead.As of November 2011, 118 elements...
that is too unstable to occur naturally on Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
, and therefore has to be created artificially. So far 30 synthetic elements have been discovered—that is, synthesized. Six of them are "quasi-synthetic"—meaning that they occur naturally on Earth in trace quantities and generally have to be produced artificially,—and 24 are "fully synthetic"—meaning that they do not occur naturally on Earth at all, and can only be produced artificially. Of all the synthetic elements, plutonium
Plutonium
Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...
—first synthesized in 1940—is the one best known to lay people, because of its use in atomic bombs and nuclear reactor
Nuclear reactor
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...
s.
Properties
Synthetic elements are radioactive and decayRadioactive decay
Radioactive decay is the process by which an atomic nucleus of an unstable atom loses energy by emitting ionizing particles . The emission is spontaneous, in that the atom decays without any physical interaction with another particle from outside the atom...
very rapidly into lighter elements—possessing half-live
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
s so short, relative to the age of the Earth (which formed 4.54 billion years ago), that any atom
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
s of these elements that may have existed when the Earth formed have long since decayed. Because of this, atoms of synthetic elements only occur on Earth as the product of experiments that involve nuclear reactor
Nuclear reactor
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...
s or particle accelerator
Particle accelerator
A particle accelerator is a device that uses electromagnetic fields to propel charged particles to high speeds and to contain them in well-defined beams. An ordinary CRT television set is a simple form of accelerator. There are two basic types: electrostatic and oscillating field accelerators.In...
s, via nuclear fusion
Nuclear fusion
Nuclear fusion is the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy...
or neutron absorption.
Atomic mass
Atomic mass
The atomic mass is the mass of a specific isotope, most often expressed in unified atomic mass units. The atomic mass is the total mass of protons, neutrons and electrons in a single atom....
for natural life is based on weighted average abundance of natural isotopes that occur in the Earth's crust and atmosphere. For synthetic elements, the isotope depends on the means of synthesis, so the concept of natural isotope abundance has no meaning. Therefore, for synthetic elements the total nucleus
Atomic nucleus
The nucleus is the very dense region consisting of protons and neutrons at the center of an atom. It was discovered in 1911, as a result of Ernest Rutherford's interpretation of the famous 1909 Rutherford experiment performed by Hans Geiger and Ernest Marsden, under the direction of Rutherford. The...
count (proton
Proton
The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number....
s plus neutron
Neutron
The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of...
s) of the most stable isotope—i.e., the isotope with the longest half-life—is listed in brackets as the atomic mass.
(Note: Just because an element is radioactive does not mean it is synthetic. For instance, uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
and thorium
Thorium
Thorium is a natural radioactive chemical element with the symbol Th and atomic number 90. It was discovered in 1828 and named after Thor, the Norse god of thunder....
have no stable isotopes but occur naturally in the Earth's crust and atmosphere; therefore, neither are synthetic. Unstable elements such as polonium
Polonium
Polonium is a chemical element with the symbol Po and atomic number 84, discovered in 1898 by Marie Skłodowska-Curie and Pierre Curie. A rare and highly radioactive element, polonium is chemically similar to bismuth and tellurium, and it occurs in uranium ores. Polonium has been studied for...
, radium
Radium
Radium is a chemical element with atomic number 88, represented by the symbol Ra. Radium is an almost pure-white alkaline earth metal, but it readily oxidizes on exposure to air, becoming black in color. All isotopes of radium are highly radioactive, with the most stable isotope being radium-226,...
, and radon
Radon
Radon is a chemical element with symbol Rn and atomic number 86. It is a radioactive, colorless, odorless, tasteless noble gas, occurring naturally as the decay product of uranium or thorium. Its most stable isotope, 222Rn, has a half-life of 3.8 days...
—which form through the decay of uranium and thorium—are also found in nature, despite their short half-lives.)
History
The first element discovered through synthesis was technetiumTechnetium
Technetium is the chemical element with atomic number 43 and symbol Tc. It is the lowest atomic number element without any stable isotopes; every form of it is radioactive. Nearly all technetium is produced synthetically and only minute amounts are found in nature...
—its discovery being definitely confirmed in 1936. This discovery filled a gap in the periodic table
Periodic table
The periodic table of the chemical elements is a tabular display of the 118 known chemical elements organized by selected properties of their atomic structures. Elements are presented by increasing atomic number, the number of protons in an atom's atomic nucleus...
, and the fact that no stable isotope
Stable isotope
Stable isotopes are chemical isotopes that may or may not be radioactive, but if radioactive, have half-lives too long to be measured.Only 90 nuclides from the first 40 elements are energetically stable to any kind of decay save proton decay, in theory...
s of technetium exist explains its natural absence on Earth (and the gap). With the longest-lived isotope of technetium, Tc-98, having a 4.2 million year half-life, no technetium remains from the formation of the Earth. Only minute traces of technetium occur naturally in the Earth's crust—as a spontaneous fission product
Fission product
Nuclear fission products are the atomic fragments left after a large atomic nucleus fissions. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons and a large release of energy in the form of heat , gamma rays and neutrinos. The...
of uranium-238 or by neutron capture
Neutron capture
Neutron capture is a kind of nuclear reaction in which an atomic nucleus collides with one or more neutrons and they merge to form a heavier nucleus. Since neutrons have no electric charge they can enter a nucleus more easily than positively charged protons, which are repelled...
in molybdenum
Molybdenum
Molybdenum , is a Group 6 chemical element with the symbol Mo and atomic number 42. The name is from Neo-Latin Molybdaenum, from Ancient Greek , meaning lead, itself proposed as a loanword from Anatolian Luvian and Lydian languages, since its ores were confused with lead ores...
ores—but technetium is present naturally in red giant
Red giant
A red giant is a luminous giant star of low or intermediate mass in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius immense and the surface temperature low, somewhere from 5,000 K and lower...
stars.
Quasi-synthetic elements
All elements with atomic numberAtomic number
In chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element...
s 1 through 94, including these, are naturally occurring at least in trace quantities.
Element name | Chemical Symbol | Atomic Number | First definite synthesis |
---|---|---|---|
Technetium Technetium Technetium is the chemical element with atomic number 43 and symbol Tc. It is the lowest atomic number element without any stable isotopes; every form of it is radioactive. Nearly all technetium is produced synthetically and only minute amounts are found in nature... |
Tc | 43 | 1936 |
Promethium Promethium Promethium is a chemical element with the symbol Pm and atomic number 61. It is notable for being the only exclusively radioactive element besides technetium that is followed by chemical elements with stable isotopes.- Prediction :... |
Pm | 61 | 1945 |
Astatine Astatine Astatine is a radioactive chemical element with the symbol At and atomic number 85. It occurs on the Earth only as the result of decay of heavier elements, and decays away rapidly, so much less is known about this element than its upper neighbors in the periodic table... |
At | 85 | 1940 |
Francium Francium Francium is a chemical element with symbol Fr and atomic number 87. It was formerly known as eka-caesium and actinium K.Actually the least unstable isotope, francium-223 It has the lowest electronegativity of all known elements, and is the second rarest naturally occurring element... |
Fr | 87 | 1939 |
Neptunium Neptunium Neptunium is a chemical element with the symbol Np and atomic number 93. A radioactive metal, neptunium is the first transuranic element and belongs to the actinide series. Its most stable isotope, 237Np, is a by-product of nuclear reactors and plutonium production and it can be used as a... |
Np | 93 | 1940 |
Plutonium Plutonium Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation... |
Pu | 94 | 1940 |
Fully synthetic elements
All elements in the following categories do not occur naturally on Earth, and have atomic numbers of 95 and higher.Transuranium elementTransuranium elementIn chemistry, transuranium elements are the chemical elements with atomic numbers greater than 92...
s
Element name | Chemical Symbol | Atomic Number | First definite synthesis |
---|---|---|---|
Americium Americium Americium is a synthetic element that has the symbol Am and atomic number 95. This transuranic element of the actinide series is located in the periodic table below the lanthanide element europium, and thus by analogy was named after another continent, America.Americium was first produced in 1944... |
Am | 95 | 1944 |
Curium Curium Curium is a synthetic chemical element with the symbol Cm and atomic number 96. This radioactive transuranic element of the actinide series was named after Marie Skłodowska-Curie and her husband Pierre Curie. Curium was first intentionally produced and identified in summer 1944 by the group of... |
Cm | 96 | 1944 |
Berkelium Berkelium Berkelium , is a synthetic element with the symbol Bk and atomic number 97, a member of the actinide and transuranium element series. It is named after the city of Berkeley, California, the location of the University of California Radiation Laboratory where it was discovered in December 1949... |
Bk | 97 | 1949 |
Californium Californium Californium is a radioactive metallic chemical element with the symbol Cf and atomic number 98. The element was first made in the laboratory in 1950 by bombarding curium with alpha particles at the University of California, Berkeley. It is the ninth member of the actinide series and was the... |
Cf | 98 | 1950 |
Einsteinium Einsteinium Einsteinium is a synthetic element with the symbol Es and atomic number 99. It is the seventh transuranic element, and an actinide.Einsteinium was discovered in the debris of the first hydrogen bomb explosion in 1952, and named after Albert Einstein... |
Es | 99 | 1952 |
Fermium Fermium Fermium is a synthetic element with the symbol Fm. It is the 100th element in the periodic table and a member of the actinide series. It is the heaviest element that can be formed by neutron bombardment of lighter elements, and hence the last element that can be prepared in macroscopic quantities,... |
Fm | 100 | 1952 |
Transfermium elementTransfermium elementA transfermium element is a chemical element with atomic number greater than 100, that of Fermium. The transfermium elements have a number of common characteristics: they do not occur naturally; they are difficult to produce in a laboratory; they have very short half lives; and are radioactive....
s
Element name | Chemical Symbol | Atomic Number | First definite synthesis |
---|---|---|---|
Mendelevium Mendelevium Mendelevium is a synthetic element with the symbol Md and the atomic number 101. A metallic radioactive transuranic element in the actinide series, mendelevium is usually synthesized by bombarding einsteinium with alpha particles. It was named after Dmitri Ivanovich Mendeleev, who created the... |
Md | 101 | 1955 |
Nobelium Nobelium Nobelium is a synthetic element with the symbol No and atomic number 102. It was first correctly identified in 1966 by scientists at the Flerov Laboratory of Nuclear Reactions in Dubna, Soviet Union... |
No | 102 | 1966 |
Lawrencium Lawrencium Lawrencium is a radioactive synthetic chemical element with the symbol Lr and atomic number 103. In the periodic table of the elements, it is a period 7 d-block element and the last element of actinide series... |
Lr | 103 | 1961 |
Transactinide elementTransactinide elementIn chemistry, transactinide elements are the chemical elements with atomic numbers greater than those of the actinides, the heaviest of which is lawrencium ....
s
Element name | Chemical Symbol | Atomic Number | First definite synthesis |
---|---|---|---|
Rutherfordium Rutherfordium Rutherfordium is a chemical element with symbol Rf and atomic number 104, named in honor of New Zealand physicist Ernest Rutherford. It is a synthetic element and radioactive; the most stable known isotope, 267Rf, has a half-life of approximately 1.3 hours.In the periodic table of the elements,... |
Rf | 104 | 1969 |
Dubnium Dubnium The Soviet team proposed the name nielsbohrium in honor of the Danish nuclear physicist Niels Bohr. The American team proposed that the new element should be named hahnium , in honor of the late German chemist Otto Hahn... |
Db | 105 | 1968 (USSR)/ 1970 (USA) * |
Seaborgium Seaborgium Seaborgium is a synthetic chemical element with the symbol Sg and atomic number 106.Seaborgium is a synthetic element whose most stable isotope 271Sg has a half-life of 1.9 minutes. A new isotope 269Sg has a potentially slightly longer half-life based on the observation of a single decay... |
Sg | 106 | 1974 |
Bohrium Bohrium Bohrium is a chemical element with the symbol Bh and atomic number 107 and is the heaviest member of group 7 .It is a synthetic element whose most stable known isotope, 270Bh, has a half-life of 61 seconds... |
Bh | 107 | 1981 |
Hassium Hassium Hassium is a synthetic element with the symbol Hs and atomic number 108. It is the heaviest member of the group 8 elements. The element was first observed in 1984... |
Hs | 108 | 1984 |
Meitnerium Meitnerium Meitnerium is a chemical element with the symbol Mt and atomic number 109. It is placed as the heaviest member of group 9 in the periodic table but a sufficiently stable isotope is not known at this time which would allow chemical experiments to confirm its position, unlike its lighter... |
Mt | 109 | 1982 |
Darmstadtium Darmstadtium Darmstadtium is a chemical element with the symbol Ds and atomic number 110. It is placed as the heaviest member of group 10, but no known isotope is sufficiently stable to allow chemical experiments to confirm its placing in that group... |
Ds | 110 | 1994 |
Roentgenium Roentgenium Roentgenium is a synthetic radioactive chemical element with the symbol Rg and atomic number 111. It is placed as the heaviest member of the group 11 elements, although a sufficiently stable isotope has not yet been produced in a sufficient amount that would confirm this position as a heavier... |
Rg | 111 | 1994 |
Copernicium | Cn | 112 | 1996 |
(* The United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
and Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
made discoveries of Dubnium independently and were given shared credit by IUPAC/IUPAP in 1992. In 1997, IUPAC decided to give the element its current name—a name suggested by the Russians—since American-chosen names had already been used for many existing synthetic elements.)
Recently observed synthetic elements
Note: Names and symbols for these elements are provisional.Element name | Chemical Symbol | Atomic Number | First definite synthesis |
---|---|---|---|
Ununtrium Ununtrium Ununtrium is the temporary name of a synthetic element with the temporary symbol Uut and atomic number 113.It is placed as the heaviest member of the group 13 elements although a sufficiently stable isotope is not known at this time that would allow chemical experiments to confirm its position... |
Uut | 113 | 2003 |
Ununquadium Ununquadium Ununquadium is the temporary name of a radioactive chemical element with the temporary symbol Uuq and atomic number 114. There is no proposed name yet, although flerovium has been discussed in the media.About 80 decays of atoms of... |
Uuq | 114 | 1999 |
Ununpentium Ununpentium Ununpentium is the temporary name of a synthetic superheavy element in the periodic table that has the temporary symbol Uup and has the atomic number 115.... |
Uup | 115 | 2003 |
Ununhexium Ununhexium Ununhexium is the temporary name of a synthetic superheavy element with the temporary symbol Uuh and atomic number 116. There is no proposed name yet although moscovium has been discussed in the media.It is placed as the heaviest member of group 16 although a sufficiently stable isotope is... |
Uuh | 116 | 2000 |
Ununseptium Ununseptium Ununseptium is the temporary name of a superheavy artificial chemical element with temporary symbol Uus and atomic number 117. Six atoms were detected by a joint Russia–US collaboration at Dubna, Moscow Oblast, Russia, in 2009–10... |
Uus | 117 | 2010 |
Ununoctium Ununoctium Ununoctium is the temporary IUPAC name for the transactinide element having the atomic number 118 and temporary element symbol Uuo. It is also known as eka-radon or element 118, and on the periodic table of the elements it is a p-block element and the last one of the 7th period. Ununoctium is... |
Uuo | 118 | 2002 |