Isotopes of nihonium

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Isotopes of nihonium  (113Nh)
Main isotopes [1] Decay
abun­dance half-life (t1/2) mode pro­duct
278Nh synth 2.0 ms α 274Rg
282Nhsynth61 msα 278Rg
283Nhsynth123 msα 279Rg
284Nhsynth0.90 sα 280Rg
ε 284Cn
285Nhsynth2.1 sα 281Rg
SF –
286Nhsynth9.5 sα 282Rg
287Nhsynth5.5 s? [2] α 283Rg
290Nhsynth2 s? [3] α 286Rg

Nihonium (113Nh) is a synthetic element. Being synthetic, a standard atomic weight cannot be given and like all artificial elements, it has no stable isotopes. The first isotope 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 radioisotopes from 278Nh to 286Nh, along with the unconfirmed 287Nh and 290Nh. The longest-lived isotope is 286Nh with a half-life of 9.5 seconds.

Contents

List of isotopes

Nuclide
 Z N Isotopic mass (Da) [4]
[n 1] [n 2] 		Half-life [1]
Decay
mode [1]
[n 3] 		Daughter
isotope
Spin and
parity [1]
278Nh113165278.17073(24)#2.0+2.7
−0.7 ms
[2.3(13) ms]		 α 274Rg
282Nh113169282.17577(43)#61+73
−22 ms [5] 		α278Rg
283Nh [n 4] 113170283.17667(47)#123+80
−35 ms [5] 		α279Rg
284Nh [n 5] 113171284.17884(57)#0.90+0.07
−0.06 s [5] 		α (≥99%)280Rg 
EC (≤1%) [5] 284Cn
285Nh [n 6] 113172285.18011(83)#2.1+0.6
−0.3 s [5] 		α (82%)281Rg
SF (18%) [5] (various)
286Nh [n 7] 113173286.18246(63)#12(5) sα282Rg
287Nh [2] [n 8] 113174287.18406(76)#5.5 sα283Rg
290Nh [n 9] 113177290.19143(50)#2.0+9.6
−0.9 s
[8(6) s]		α286Rg
SF (<50%)(various)
This table header & footer:
  1. ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  2. ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  3. ↑ Modes of decay:
    EC: Electron capture
  4. ↑ Not directly synthesized, occurs as decay product of 287Mc
  5. ↑ Not directly synthesized, occurs as decay product of 288Mc
  6. ↑ Not directly synthesized, occurs in decay chain of 293Ts
  7. ↑ Not directly synthesized, occurs in decay chain of 294Ts
  8. ↑ Not directly synthesized, occurs in decay chain of 287Fl; unconfirmed
  9. ↑ Not directly synthesized, occurs in decay chain of 290Fl and 294Lv; unconfirmed

Isotopes and nuclear properties

Nucleosynthesis

Super-heavy elements such as nihonium are produced by bombarding lighter elements in particle accelerators that induce fusion reactions. 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 numbers. [6]

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 (actinides), giving rise to compound nuclei at high excitation energy (~40–50  MeV) that may either fission or evaporate several (3 to 5) neutrons. [7] 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. [6] The latter is a distinct concept from that of where nuclear fusion claimed to be achieved at room temperature conditions (see cold fusion). [8]

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. [9] They repeated the experiment in 2003 again without success. [9] 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. [10] They repeated the reaction in several runs in 2005 and were able to synthesize a second atom, [11] followed by a third in 2012. [12]

The table below contains various combinations of targets and projectiles which could be used to form compound nuclei with Z=113.

TargetProjectileCNAttempt result
208Pb71Ga279NhReaction yet to be attempted
209Bi70Zn279NhSuccessful reaction
238U45Sc283NhReaction yet to be attempted
237Np48Ca285NhSuccessful reaction
244Pu41K285NhReaction yet to be attempted
250Cm37Cl287NhReaction yet to be attempted
248Cm37Cl285NhReaction yet to be attempted

Hot fusion

In June 2006, the Dubna-Livermore team synthesised nihonium directly by bombarding a neptunium-237 target with accelerated calcium-48 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: [13]

237
93Np
 + 48
20Ca
 → 282
113Nh
 + 3 1
0n

Two atoms of 282Nh were detected. [13]

As decay product

List of nihonium isotopes observed by decay
Evaporation residueObserved nihonium isotope
294Lv, 290Fl ?290Nh ? [3]
287Fl ?287Nh ? [2]
294Ts, 290Mc286Nh [14]
293Ts, 289Mc285Nh [14]
288Mc284Nh [15]
287Mc283Nh [15]
286Mc282Nh

Nihonium has been observed as a decay product of moscovium (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. [16] For example, in January 2010, the Dubna team (JINR) identified nihonium-286 as a product in the decay of tennessine via an alpha decay sequence: [14]

294
117Ts
 → 290
115Mc
 + 4
2He
290
115Mc
 → 286
113Nh
 + 4
2He

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

TargetProjectileCNChannel (product)σmaxModelRef
209Bi70Zn279Nh1n (278Nh)30 fbDNS [17]
238U45Sc283Nh3n (280Nh)20 fbDNS [18]
237Np48Ca285Nh3n (282Nh)0.4 pbDNS [19]
244Pu41K285Nh3n (282Nh)42.2 fbDNS [18]
250Cm37Cl287Nh4n (283Nh)0.594 pbDNS [18]
248Cm37Cl285Nh3n (282Nh)0.26 pbDNS [18]

Related Research Articles

Rutherfordium is a synthetic chemical element; it has symbol Rf and atomic number 104. It is named after physicist Ernest Rutherford. As a synthetic element, it is not found in nature and can only be made in a particle accelerator. It is radioactive; the most stable known isotope, 267Rf, has a half-life of about 48 minutes.

Darmstadtium is a synthetic chemical element; it has symbol Ds and atomic number 110. It is extremely radioactive: the most stable known isotope, darmstadtium-281, has a half-life of approximately 14 seconds. Darmstadtium was first created in 1994 by the GSI Helmholtz Centre for Heavy Ion Research in the city of Darmstadt, Germany, after which it was named.

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 Lawrence Livermore National Laboratory in the United States, which collaborated with the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, to discover livermorium during experiments conducted between 2000 and 2006. The name of the laboratory refers to the city of Livermore, California, where it is located, which in turn was named after the rancher and landowner Robert Livermore. The name was adopted by IUPAC on May 30, 2012. Five isotopes of livermorium are known, with mass numbers of 288 and 290–293 inclusive; the longest-lived among them is livermorium-293 with a half-life of about 80 milliseconds. A sixth possible isotope with mass number 294 has been reported but not yet confirmed.

<span class="mw-page-title-main">Island of stability</span> Predicted set of isotopes of relatively more stable superheavy elements

In nuclear physics, the island of stability is a predicted set of isotopes of superheavy elements that may have considerably longer half-lives than known isotopes of these elements. It is predicted to appear as an "island" in the chart of nuclides, separated from known stable and long-lived primordial radionuclides. Its theoretical existence is attributed to stabilizing effects of predicted "magic numbers" of protons and neutrons in the superheavy mass region.

Moscovium is a synthetic chemical element; it has 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, it was recognized as one of four new elements by the Joint Working Party of international scientific bodies IUPAC and IUPAP. On 28 November 2016, it was officially named after the Moscow Oblast, in which the JINR is situated.

Flerovium is a synthetic chemical element; it has symbol Fl and atomic number 114. It is an extremely radioactive, superheavy element, named after the Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research in Dubna, Russia, where the element was discovered in 1999. The lab's name, in turn, honours Russian physicist Georgy Flyorov. IUPAC adopted the name on 30 May 2012. The name and symbol had previously been proposed for element 102 (nobelium), but was not accepted by IUPAC at that time.

Nihonium is a synthetic chemical element; it has 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 element in the p-block. It is a member of period 7 and group 13.

Rutherfordium (104Rf) is a synthetic element and thus has no stable isotopes. A standard atomic weight cannot be given. The first isotope to be synthesized was either 259Rf in 1966 or 257Rf in 1969. There are 16 known radioisotopes from 253Rf to 270Rf and several isomers. The longest-lived isotope is 267Rf with a half-life of 48 minutes, and the longest-lived isomer is 263mRf with a half-life of 8 seconds.

Bohrium (107Bh) is an artificial element. Like all artificial elements, it has no stable isotopes, and a standard atomic weight cannot be given. The first isotope to be synthesized was 262Bh in 1981. There are 11 known isotopes ranging from 260Bh to 274Bh, and 1 isomer, 262mBh. The longest-lived isotope is 270Bh with a half-life of 2.4 minutes, although the unconfirmed 278Bh may have an even longer half-life of about 690 seconds.

Hassium (108Hs) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 265Hs in 1984. There are 13 known isotopes from 263Hs to 277Hs and up to six isomers. The most stable known isotope is 271Hs, with a half-life of about 46 seconds, though this assignment is not definite due to uncertainty arising from a low number of measurements. The isotopes 269Hs and 270Hs respectively have half-lives of about 12 seconds and 7.6 seconds. It is also possible that the isomer 277mHs is more stable than these, with a reported half-life 130±100 seconds, but only one event of decay of this isotope has been registered as of 2016.

Meitnerium (109Mt) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 266Mt in 1982, and this is also the only isotope directly synthesized; all other isotopes are only known as decay products of heavier elements. There are eight known isotopes, from 266Mt to 278Mt. There may also be two isomers. The longest-lived of the known isotopes is 278Mt with a half-life of 8 seconds. The unconfirmed heavier 282Mt appears to have an even longer half-life of 67 seconds.

Darmstadtium (110Ds) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 269Ds in 1994. There are 11 known radioisotopes from 267Ds to 281Ds and 2 or 3 known isomers. The longest-lived isotope is 281Ds with a half-life of 14 seconds. However, the unconfirmed 282Ds might have an even longer half-life of 67 seconds.

Roentgenium (111Rg) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 272Rg in 1994, which is also the only directly synthesized isotope; all others are decay products of heavier elements. There are seven known radioisotopes, having mass numbers of 272, 274, and 278–282. The longest-lived isotope is 282Rg with a half-life of about 2 minutes, although the unconfirmed 283Rg and 286Rg may have longer half-lives of about 5.1 minutes and 10.7 minutes respectively.

Copernicium (112Cn) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 277Cn in 1996. There are 6 known radioisotopes ; the longest-lived isotope is 285Cn with a half-life of 30 seconds.

Flerovium (114Fl) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 289Fl in 1999. Flerovium has six known isotopes, along with the unconfirmed 290Fl, and possibly two nuclear isomers. The longest-lived isotope is 289Fl with a half-life of 1.9 seconds, but 290Fl may have a longer half-life of 19 seconds.

Moscovium (115Mc) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no known stable isotopes. The first isotope to be synthesized was 288Mc in 2004. There are five known radioisotopes from 286Mc to 290Mc. The longest-lived isotope is 290Mc with a half-life of 0.65 seconds.

Livermorium (116Lv) is a synthetic element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 293Lv in 2000. There are five known radioisotopes, with mass numbers 288 and 290–293, as well as a few suggestive indications of a possible heavier isotope 294Lv. The longest-lived known isotope is 293Lv with a half-life of 53 ms.

Tennessine (117Ts) is the most-recently synthesized synthetic element, and much of the data is hypothetical. As for any synthetic element, a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotopes to be synthesized were 293Ts and 294Ts in 2009. The longer-lived isotope is 294Ts with a half-life of 51 ms.

Oganesson (118Og) is a synthetic element created in particle accelerators, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first and only isotope to be synthesized was 294Og in 2002 and 2005; it has a half-life of 0.58 milliseconds.

Unbiunium, also known as eka-actinium or element 121, is a hypothetical chemical element; it has symbol Ubu and atomic number 121. Unbiunium and Ubu are the temporary systematic IUPAC name and symbol respectively, which are used until the element is discovered, confirmed, and a permanent name is decided upon. In the periodic table of the elements, it is expected to be the first of the superactinides, and the third element in the eighth period. It has attracted attention because of some predictions that it may be in the island of stability. It is also likely to be the first of a new g-block of elements.

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