Nihonium Nihonium is a synthetic chemical element; it has symbol Nh and atomic number 113. It is extremely radioactive: its most stable known isotope, nihonium-286, has a half-life of about 10 seconds. In the periodic table, nihonium is a transactini ...

(₁₁₃Nh) is a

synthetic element A synthetic element is a known chemical element that does not occur naturally on Earth: it has been created by human manipulation of fundamental particles in a nuclear reactor, a particle accelerator, or the explosion of an atomic bomb; thus, it i ...

. Being synthetic, a

standard atomic weight The standard atomic weight of a chemical element (symbol ''A''r°(E) for element "E") is the weighted arithmetic mean of the relative isotopic masses of all isotopes of that element weighted by each isotope's abundance on Earth. For example, ...

cannot be given and like all artificial elements, it has no

stable isotope Stable nuclides are Isotope, isotopes of a chemical element whose Nucleon, nucleons are in a configuration that does not permit them the surplus energy required to produce a radioactive emission. The Atomic nucleus, nuclei of such isotopes are no ...

s. The first

isotope Isotopes are distinct nuclear species (or ''nuclides'') of the same chemical element. They have the same atomic number (number of protons in their Atomic nucleus, nuclei) and position in the periodic table (and hence belong to the same chemica ...

to be synthesized was ²⁸⁴Nh as a

decay product In nuclear physics, a decay product (also known as a daughter product, daughter isotope, radio-daughter, or daughter nuclide) is the remaining nuclide left over from radioactive decay. Radioactive decay often proceeds via a sequence of steps ( d ...

of ²⁸⁸Mc in 2003. The first isotope to be directly synthesized was ²⁷⁸Nh in 2004. There are 6 known

radioisotope A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess numbers of either neutrons or protons, giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ...

s from ²⁷⁸Nh to ²⁸⁶Nh, along with the unconfirmed ²⁸⁷Nh and ²⁹⁰Nh. The longest-lived isotope is ²⁸⁶Nh with a

half-life Half-life is a mathematical and scientific description of exponential or gradual decay. Half-life, half life or halflife may also refer to: Film * Half-Life (film), ''Half-Life'' (film), a 2008 independent film by Jennifer Phang * ''Half Life: ...

of 9.5 seconds.

List of isotopes

, -id=Nihonium-278 , ²⁷⁸Nh , 113 , 165 , 278.17073(24)# ,
[] , alpha decay, α , ²⁷⁴Rg , , -id=Nihonium-282 , ²⁸²Nh , 113 , 169 , 282.17577(43)# , , α , ²⁷⁸Rg , , -id=Nihonium-283 , ²⁸³NhNot directly synthesized, occurs as

of ²⁸⁷Mc , 113 , 170 , 283.17667(47)# , , α , ²⁷⁹Rg , , -id=Nihonium-284 , rowspan=2, ²⁸⁴NhNot directly synthesized, occurs as decay product of ²⁸⁸Mc , rowspan=2, 113 , rowspan=2, 171 , rowspan=2, 284.17884(57)# , rowspan=2, , α (≥99%) , ²⁸⁰Rg , rowspan=2, , - , EC (≤1%) , ²⁸⁴Cn , -id=Nihonium-285 , rowspan=2, ²⁸⁵NhNot directly synthesized, occurs in

decay chain In nuclear science a decay chain refers to the predictable series of radioactive disintegrations undergone by the nuclei of certain unstable chemical elements. Radioactive isotopes do not usually decay directly to stable isotopes, but rather ...

of ²⁹³Ts , rowspan=2, 113 , rowspan=2, 172 , rowspan=2, 285.18011(83)# , rowspan=2, , α (82%) , ²⁸¹Rg , , - , SF (18%) , (various) , -id=Nihonium-286 , ²⁸⁶NhNot directly synthesized, occurs in decay chain of ²⁹⁴Ts , 113 , 173 , 286.18246(63)# ,
[] , α , ²⁸²Rg , , -id=Nihonium-287 , ²⁸⁷NhNot directly synthesized, occurs in decay chain of ²⁸⁷Fl; unconfirmed , 113 , 174 , 287.18406(76)# , 5.5 s , α , ²⁸³Rg , , -id=Nihonium-290 , rowspan=2, ²⁹⁰NhNot directly synthesized, occurs in decay chain of ²⁹⁰Fl and ²⁹⁴Lv; unconfirmed , rowspan=2, 113 , rowspan=2, 177 , rowspan=2, 290.19143(50)# , rowspan=2,
(6) s, α , ²⁸⁶Rg , rowspan=2, , - , SF (<50%) , (various)

Isotopes and nuclear properties

Nucleosynthesis

Super-heavy elements such as nihonium are produced by bombarding lighter elements in

particle accelerator A particle accelerator is a machine that uses electromagnetic fields to propel electric charge, charged particles to very high speeds and energies to contain them in well-defined particle beam, beams. Small accelerators are used for fundamental ...

s that induce

fusion reaction Nuclear fusion is a reaction in which two or more atomic nuclei combine to form a larger nuclei, nuclei/neutron by-products. The difference in mass between the reactants and products is manifested as either the release or absorption of energy ...

s. Whereas most of the isotopes of nihonium can be synthesized directly this way, some heavier ones have only been observed as decay products of elements with higher

atomic number The atomic number or nuclear charge number (symbol ''Z'') of a chemical element is the charge number of its atomic nucleus. For ordinary nuclei composed of protons and neutrons, this is equal to the proton number (''n''p) or the number of pro ...

s. Depending on the energies involved, the former are separated into "hot" and "cold". In hot fusion reactions, very light, high-energy projectiles are accelerated toward very heavy targets (

actinide The actinide () or actinoid () series encompasses at least the 14 metallic chemical elements in the 5f series, with atomic numbers from 89 to 102, actinium through nobelium. Number 103, lawrencium, is also generally included despite being part ...

s), giving rise to compound nuclei at high excitation energy (~40–50

MeV In physics, an electronvolt (symbol eV), also written electron-volt and electron volt, is the measure of an amount of kinetic energy gained by a single electron accelerating through an electric potential difference of one volt in vacuum. When us ...

) that may either fission or evaporate several (3 to 5) neutrons. In cold fusion reactions, the produced fused nuclei have a relatively low excitation energy (~10–20 MeV), which decreases the probability that these products will undergo fission reactions. As the fused nuclei cool to the

ground state The ground state of a quantum-mechanical system is its stationary state of lowest energy; the energy of the ground state is known as the zero-point energy of the system. An excited state is any state with energy greater than the ground state ...

, they require emission of only one or two neutrons, and thus, allows for the generation of more neutron-rich products. The latter is a distinct concept from that of where nuclear fusion claimed to be achieved at room temperature conditions (see

cold fusion Cold fusion is a hypothesized type of nuclear reaction that would occur at, or near, room temperature. It would contrast starkly with the nuclear fusion, "hot" fusion that is known to take place naturally within Main sequence, stars and artific ...

Cold fusion

Before the synthesis of nihonium by the RIKEN team, scientists at the Institute for Heavy Ion Research (Gesellschaft für Schwerionenforschung) in

Darmstadt Darmstadt () is a city in the States of Germany, state of Hesse in Germany, located in the southern part of the Frankfurt Rhine Main Area, Rhine-Main-Area (Frankfurt Metropolitan Region). Darmstadt has around 160,000 inhabitants, making it the ...

, Germany also tried to synthesize nihonium by bombarding bismuth-209 with zinc-70 in 1998. No nihonium atoms were identified in two separate runs of the reaction."Search for element 113"
, Hofmann et al., ''GSI report 2003''. Retrieved on 3 March 2008 They repeated the experiment in 2003 again without success. In late 2003, the emerging team at

RIKEN is a national scientific research institute in Japan. Founded in 1917, it now has about 3,000 scientists on seven campuses across Japan, including the main site at Wakō, Saitama, Wakō, Saitama Prefecture, on the outskirts of Tokyo. Riken is a ...

using their efficient apparatus GARIS attempted the reaction and reached a limit of 140 fb. In December 2003 – August 2004, they resorted to "brute force" and carried out the reaction for a period of eight months. They were able to detect a single atom of ²⁷⁸Nh. They repeated the reaction in several runs in 2005 and were able to synthesize a second atom, followed by a third in 2012. The table below contains various combinations of targets and projectiles which could be used to form compound nuclei with Z=113.

Hot fusion

In June 2006, the Dubna-Livermore team synthesised nihonium directly by bombarding a

neptunium Neptunium is a chemical element; it has chemical symbol, symbol Np and atomic number 93. A radioactivity, radioactive actinide metal, neptunium is the first transuranic element. It is named after Neptune, the planet beyond Uranus in the Solar Syste ...

-237 target with accelerated

calcium-48 Calcium-48 is a scarce isotope of calcium containing 20 protons and 28 neutrons. It makes up 0.187% of natural calcium by mole fraction. Although it is unusually neutron-rich for such a light nucleus, its beta decay is extremely hindered, and so ...

nuclei, in a search for the lighter isotopes ²⁸¹Nh and ²⁸²Nh and their decay products, to provide insight into the stabilizing effects of the closed neutron shells at ''N'' = 162 and ''N'' = 184: : + → + 3 Two atoms of ²⁸²Nh were detected.

As decay product

Nihonium has been observed as a decay product of

moscovium Moscovium is a synthetic element, synthetic chemical element; it has Chemical symbol, symbol Mc and atomic number 115. It was first synthesized in 2003 by a joint team of Russian and American scientists at the Joint Institute for Nuclear Resea ...

(via alpha decay). Moscovium currently has five known isotopes; all of them undergo alpha decays to become nihonium nuclei, with mass numbers between 282 and 286. Parent moscovium nuclei can be themselves decay products of

tennessine Tennessine is a synthetic element; it has Chemical symbol, symbol Ts and atomic number 117. It has the second-highest atomic number and joint-highest atomic mass of all known elements and is the penultimate element of the Period 7 element, 7th ...

. It may also occur as a decay product of flerovium (via electron capture), and parent flerovium nuclei can be themselves decay products of

livermorium Livermorium is a synthetic chemical element; it has symbol Lv and atomic number 116. It is an extremely radioactive element that has only been created in a laboratory setting and has not been observed in nature. The element is named after the La ...

. For example, in January 2010, the Dubna team (

JINR The Joint Institute for Nuclear Research (JINR, ), in Dubna, Moscow Oblast (110 km north of Moscow), Russia, is an international research center for nuclear sciences, with 5,500 staff members including 1,200 researchers holding over 1,000 ...

) identified nihonium-286 as a product in the decay of tennessine via an alpha decay sequence: : → + : → +

Theoretical calculations

Evaporation residue cross sections

The below table contains various targets-projectile combinations for which calculations have provided estimates for cross section yields from various neutron evaporation channels. The channel with the highest expected yield is given. DNS = Di-nuclear system; σ = cross section

References

* Half-life, spin, and isomer data selected from the following sources. ** ** ** {{Navbox element isotopes Nihonium