Nihonium Nihonium is a synthetic chemical element with the 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 transactinide ...

(₁₁₃Nh) is a

synthetic element A synthetic element is one of 24 known chemical elements that do not occur naturally on Earth: they have been created by human manipulation of fundamental particles in a nuclear reactor, a particle accelerator, or the explosion of an atomic bomb; ...

. Being synthetic, a standard atomic weight cannot be given and like all artificial elements, it has no

stable isotope The term stable isotope has a meaning similar to stable nuclide, but is preferably used when speaking of nuclides of a specific element. Hence, the plural form stable isotopes usually refers to isotopes of the same element. The relative abundanc ...

s. The first

isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numb ...

to be synthesized was ²⁸⁴Nh as a decay product 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 nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferr ...

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

half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable at ...

of 8 seconds.

List of isotopes

, - , ²⁷⁸Nh , 113 , 165 , 278.17058(20)# , 1.4 ms , α , ²⁷⁴Rg , , - , ²⁸²Nh , 113 , 169 , 282.17567(39)# , , α , ²⁷⁸Rg , , - , ²⁸³NhNot directly synthesized, occurs as decay product of ²⁸⁷Mc , 113 , 170 , 283.17657(52)# , , α , ²⁷⁹Rg , , - , rowspan=2, ²⁸⁴NhNot directly synthesized, occurs as decay product of ²⁸⁸Mc , rowspan=2, 113 , rowspan=2, 171 , rowspan=2, 284.17873(62)# , rowspan=2, , α (≥99%) , ²⁸⁰Rg , rowspan=2, , - , EC (≤1%) , ²⁸⁴Cn , - , rowspan=2, ²⁸⁵NhNot directly synthesized, occurs in

decay chain In nuclear science, the decay chain refers to a series of radioactive decays of different radioactive decay products as a sequential series of transformations. It is also known as a "radioactive cascade". Most radioisotopes do not decay dire ...

of ²⁹³Ts , rowspan=2, 113 , rowspan=2, 172 , rowspan=2, 285.17973(89)# , rowspan=2, , α (82%) , ²⁸¹Rg , , - , SF (18%) , (various) , - , ²⁸⁶NhNot directly synthesized, occurs in decay chain of ²⁹⁴Ts , 113 , 173 , 286.18221(72)# , 9.5 s , α , ²⁸²Rg , , - , ²⁸⁷NhNot directly synthesized, occurs in decay chain of ²⁸⁷Fl; unconfirmed , 113 , 174 , 287.18339(81)# , 5.5 s , α , ²⁸³Rg , , - , ²⁹⁰NhNot directly synthesized, occurs in decay chain of ²⁹⁰Fl and ²⁹⁴Lv; unconfirmed , 113 , 177 , , 2 s? , α , ²⁸⁶Rg ,

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 charged particles to very high speeds and energies, and to contain them in well-defined beams. Large accelerators are used for fundamental research in particle ...

s that induce

fusion reaction Nuclear fusion is a reaction in which two or more atomic nuclei are combined to form one or more different atomic nuclei and subatomic particles (neutrons or protons). The difference in mass between the reactants and products is manifeste ...

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 an atomic nucleus. For ordinary nuclei, this is equal to the proton number (''n''p) or the number of protons found in the nucleus of every ...

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 the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium. The actinide series derives its name from the first element in the series, actinium. The info ...

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 from rest through an electric potential difference of one volt in vacu ...

) 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, 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 "hot" fusion that is known to take place naturally within stars and artificially in hydrogen bombs and p ...

Cold fusion

Before the synthesis of nihonium by the RIKEN team, scientists at the Institute for Heavy Ion Research (Gesellschaft für Schwerionenforschung) in Darmstadt, 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 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 with the symbol Np and atomic number 93. A radioactive actinide metal, neptunium is the first transuranic element. Its position in the periodic table just after uranium, named after the planet Uranus, led to it bein ...

-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 with the 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 Research (JINR) in Dubna, Russia. In December 2015, ...

(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. It may also occur as a decay product of flerovium (via electron capture), and parent flerovium nuclei can be themselves decay products of livermorium. To date, no other elements have been known to decay to nihonium. For example, in January 2010, the Dubna team (Joint Institute for Nuclear Research, JINR) 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

* Isotope masses from: ** ** * Isotopic compositions and standard atomic masses from: ** ** * Half-life, spin, and isomer data selected from the following sources. ** ** ** {{Navbox element isotopes Isotopes of nihonium, Nihonium Lists of isotopes by element, Nihonium