Oganesson (NEW ELEMENT) - Periodic Table of Videos

Oganesson (symbol Og) is a transactinide chemical element with the atomic number 118. It was first synthesized in 2002 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. It was formally named on 28 November 2016. The name is in line with the tradition of honoring a scientist and recognizes nuclear physicist Yuri Oganessian, who has played a leading role in the discovery of the heaviest elements in the periodic table. It is one of only two elements named after a living person at the time of naming, the other being seaborgium.

Oganesson has the highest atomic number and highest atomic mass of all known elements. The radioactive oganesson atom is very unstable, and since 2005, only four atoms of the isotope Og have been detected. Although this allowed very little experimental characterization of its properties and possible compounds, theoretical calculations have resulted in many predictions, including some surprising ones. For example, although oganesson is a member of group 18 – the first synthetic one to be so – it may be significantly reactive, unlike all the other elements of that group (the noble gases). It was formerly thought to be a gas under normal conditions but is now predicted to be a solid due to relativistic effects. On the periodic table of the elements it is a p-block element and the last one of the 7th period.

HISTORY:

Early speculation

The Danish physicist Niels Bohr was the first to seriously consider the possibility of an element with atomic number as high as 118, noting in 1922 that such an element would take its place in the periodic table below radon as the seventh noble gas. Following this, Aristid von Grosse wrote an article in 1965 predicting the likely properties of element 118. These were remarkably early predictions, given that it was not yet known how to produce elements artificially in 1922, and that the existence of the island of stability had not yet been theorized in 1965. It took eighty years from Bohr's initial prediction before oganesson was first successfully synthesised, although its chemical properties have not yet been investigated to see if it really does behave as the heavier congener of radon.

Unsuccessful synthesis attempts

In late 1998, Polish physicist Robert Smolańczuk published calculations on the fusion of atomic nuclei towards the synthesis of superheavy atoms, including oganesson.^[15] His calculations suggested that it might be possible to make oganesson by fusing lead with krypton under carefully controlled conditions.

In 1999, researchers at Lawrence Berkeley National Laboratory made use of these predictions and announced the discovery of livermorium and oganesson, in a paper published in Physical Review Letters, and very soon after the results were reported in Science. The researchers reported to have performed the reaction

86
36Kr
 + 208
82Pb
 → 293
118Og
 + 
n
.

The following year, they published a retraction after researchers at other laboratories were unable to duplicate the results and the Berkeley lab could not duplicate them either. In June 2002, the director of the lab announced that the original claim of the discovery of these two elements had been based on data fabricated by principal author Victor Ninov.

Discovery reports

The first decay of atoms of oganesson was observed in 2002 at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, by a joint team of Russian and American scientists. Headed by Russian nuclear physicist Yuri Oganessian, the team included American scientists of the Lawrence Livermore National Laboratory, California. On 9 October 2006, the researchers announced that they had indirectly detected a total of three (possibly four) nuclei of oganesson-294 (one or two in 2002 and two more in 2005) produced via collisions of californium-249 atoms and calcium-48 ions.

249
98Cf
 + 48
20Ca
 → 294
118Og
 + 3 
n
.

Radioactive decay pathway of the isotope oganesson-294.^[9] The decay energy and average half-life is given for the parent isotope and each daughter isotope. The fraction of atoms undergoing spontaneous fission (SF) is given in green.

In 2011, IUPAC evaluated the 2006 results of the Dubna–Livermore collaboration and concluded: "The three events reported for the Z = 118 isotope have very good internal redundancy but with no anchor to known nuclei do not satisfy the criteria for discovery".

Because of the very small fusion reaction probability (the fusion cross section is ~0.3–0.6 pb or (3–6)×10⁻⁴¹ m²) the experiment took four months and involved a beam dose of 2.5×10¹⁹ calcium ions that had to be shot at the californium target to produce the first recorded event believed to be the synthesis of oganesson. Nevertheless, researchers are highly confident that the results are not a false positive, since the chance that the detections were random events was estimated to be less than one part in 100000.

In the experiments, the alpha-decay of three atoms of oganesson was observed. A fourth decay by direct spontaneous fission was also proposed. A half-life of 0.89 ms was calculated: 294Og decays into 290Lv by alpha decay. Since there were only three nuclei, the half-life derived from observed lifetimes has a large uncertainty: 0.89+1.07
−0.31 ms.

294
118Og
 → 290
116Lv
 + 4
2He

The identification of the 294Og nuclei was verified by separately creating the putative daughter nucleus 290Lv directly by means of a bombardment of 245Cm with 48Ca ions,

245
96Cm
 + 48
20Ca
 → 290
116Lv
 + 3 
n
,

and checking that the 290Lv decay matched the decay chain of the 294Og nuclei. The daughter nucleus 290Lv is very unstable, decaying with a lifetime of 14 milliseconds into 286Fl, which may experience either spontaneous fission or alpha decay into 282Cn, which will undergo spontaneous fission.

In a quantum-tunneling model, the alpha decay half-life of 294Og was predicted to be 0.66+0.23
−0.18 ms with the experimental Q-value published in 2004. Calculation with theoretical Q-values from the macroscopic-microscopic model of Muntian–Hofman–Patyk–Sobiczewski gives somewhat lower but comparable results.

Confirmation

In December 2015, the Joint Working Party of international scientific bodies International Union of Pure and Applied Chemistry (IUPAC) and International Union of Pure and Applied Physics (IUPAP) recognized the element's discovery and assigned the priority of the discovery to the Dubna–Livermore collaboration.

Naming

Using Mendeleev's nomenclature for unnamed and undiscovered elements, oganesson is sometimes known as eka-radon (until the 1960s as eka-emanation, emanation being the old name for radon).^[35] In 1979, IUPAC assigned the systematic placeholder name ununoctium to the undiscovered element, with the corresponding symbol of Uuo, and recommended it to be used until after confirmed discovery of the element. Although widely used in the chemical community on all levels, from chemistry classrooms to advanced textbooks, the recommendations are mostly ignored among scientists in the field, who call it "element 118", with the symbol of (118) or even simply 118.

Before the retraction in 2002, the researchers from Berkeley had intended to name the element ghiorsium (Gh), after Albert Ghiorso (a leading member of the research team).

The Russian discoverers reported their synthesis in 2006. According to IUPAC recommendations, the discoverers of a new element have the right to suggest a name. In 2007, the head of the Russian institute stated the team were considering two names for the new element: flyorium, in honor of Georgy Flyorov, the founder of the research laboratory in Dubna; and moskovium, in recognition of the Moscow Oblast where Dubna is located. He also stated that although the element was discovered as an American collaboration, who provided the californium target, the element should rightly be named in honor of Russia since the Flerov Laboratory of Nuclear Reactions at JINR was the only facility in the world which could achieve this result. These names were later proposed for element 114 (flerovium) and element 116 (moscovium). However, the final name proposed for element 116 was instead livermorium, and the name moscovium was later proposed for element 115 instead.

Traditionally, the names of all noble gases end in "-on", with the exception of helium, which was not known to be a noble gas when discovered. The IUPAC guidelines valid at the moment of the discovery approval however required all new elements be named with the ending "-ium". While the provisional name ununoctium followed this convention, a new IUPAC recommendation published in 2016 recommends using the "-on" ending for new group 18 elements, no matter whether they turn out to be a noble gas or not.

In June 2016 IUPAC announced that it planned to give the element the name oganesson (symbol: Og), in honour of the Russian nuclear physicist Yuri Oganessian, and the name became official on 28 November 2016.