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Chemical element, symbol Nh and atomic number 113 / From Wikipedia, the free encyclopedia

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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 transactinide element in the p-block. It is a member of period 7 and group 13.

Quick facts: Nihonium, Pronunciation, Mass number, Nihoniu...
Nihonium, 113Nh
Pronunciation/nɪˈhniəm/ (nih-HOH-nee-əm)
Mass number[286]
Nihonium in the periodic table


Atomic number (Z)113
Groupgroup 13 (boron group)
Periodperiod 7
Block  p-block
Electron configuration[Rn] 5f14 6d10 7s2 7p1 (predicted)[1]
Electrons per shell2, 8, 18, 32, 32, 18, 3 (predicted)
Physical properties
Phase at STPsolid (predicted)[1][2][3]
Melting point700 K (430 °C, 810 °F) (predicted)[1]
Boiling point1430 K (1130 °C, 2070 °F) (predicted)[1][4]
Density (near r.t.)16 g/cm3 (predicted)[4]
Heat of fusion7.61 kJ/mol (extrapolated)[3]
Heat of vaporisation130 kJ/mol (predicted)[2][4]
Atomic properties
Oxidation states(−1), (+1), (+3), (+5) (predicted)[1][4][5]
Ionisation energies
  • 1st: 704.9 kJ/mol (predicted)[1]
  • 2nd: 2240 kJ/mol (predicted)[4]
  • 3rd: 3020 kJ/mol (predicted)[4]
  • (more)
Atomic radiusempirical: 170 pm (predicted)[1]
Covalent radius172180 pm (extrapolated)[3]
Other properties
Natural occurrencesynthetic
Crystal structure hexagonal close-packed (hcp)
Hexagonal close-packed crystal structure for nihonium

CAS Number54084-70-7
NamingAfter Japan (Nihon in Japanese)
DiscoveryRiken (Japan, first undisputed claim 2004)
JINR (Russia) and Livermore (US, first announcement 2003)
Isotopes of nihonium
Main isotopes[8] Decay
abun­dance half-life (t1/2) mode pro­duct
278Nh synth 0.002 s α 274Rg
282Nh synth 0.061 s α 278Rg
283Nh synth 0.123 s α 279Rg
284Nh synth 0.90 s α 280Rg
ε 284Cn
285Nh synth 2.1 s α 281Rg
286Nh synth 9.5 s α 282Rg
287Nh synth 5.5 s?[9] α 283Rg
290Nh synth 2 s?[10] α 286Rg
Symbol_category_class.svg Category: Nihonium
| references

Nihonium was first reported to have been created in 2003 by a Russian–American collaboration at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, and in 2004 by a team of Japanese scientists at Riken in Wakō, Japan. The confirmation of their claims in the ensuing years involved independent teams of scientists working in the United States, Germany, Sweden, and China, as well as the original claimants in Russia and Japan. In 2015, the IUPAC/IUPAP Joint Working Party recognised the element and assigned the priority of the discovery and naming rights for the element to Riken. The Riken team suggested the name nihonium in 2016, which was approved in the same year. The name comes from the common Japanese name for Japan (日本, nihon).

Very little is known about nihonium, as it has only been made in very small amounts that decay within seconds. The anomalously long lives of some superheavy nuclides, including some nihonium isotopes, are explained by the "island of stability" theory. Experiments support the theory, with the half-lives of the confirmed nihonium isotopes increasing from milliseconds to seconds as neutrons are added and the island is approached. Nihonium has been calculated to have similar properties to its homologues boron, aluminium, gallium, indium, and thallium. All but boron are post-transition metals, and nihonium is expected to be a post-transition metal as well. It should also show several major differences from them; for example, nihonium should be more stable in the +1 oxidation state than the +3 state, like thallium, but in the +1 state nihonium should behave more like silver and astatine than thallium. Preliminary experiments in 2017 showed that elemental nihonium is not very volatile; its chemistry remains largely unexplored.

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