Ununoctium is the temporary
IUPACThe International Union of Pure and Applied Chemistry is an international federation of National Adhering Organizations that represents chemists in individual countries. It is a member of the International Council for Science . The international headquarters of IUPAC is located in Zürich,...
nameA systematic element name is the temporary name and symbol assigned to newly synthesized and not yet synthesized chemical elements. In chemistry, a transuranic element receives a permanent name and symbol only after its synthesis has been confirmed. In some cases, this has been a protracted and...
for the
transactinide elementIn chemistry, transactinide elements are the chemical elements with atomic numbers greater than those of the actinides, the heaviest of which is lawrencium ....
having the
atomic numberIn chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element...
118 and temporary
element symbolA chemical symbol is a 1- or 2-letter internationally agreed code for a chemical element, usually derived from the name of the element, often in Latin. Only the first letter is capitalised...
Uuo. It is also known as
eka-radonProfessor Dmitri Mendeleev published the first Periodic Table of the Atomic Elements in 1869 based on properties which appeared with some regularity as he laid out the elements from lightest to heaviest....
or
element 118, and on the periodic table of the elements it is a
p-blockThe p-block of the periodic table of the elements consists of the last six groups minus helium . In the elemental form of the p-block elements, the highest energy electron occupies a p-orbital.-See also:...
element and the last one of the 7th period. Ununoctium is currently the only
syntheticIn chemistry, a synthetic element is a chemical element that is too unstable to occur naturally on Earth, and therefore has to be created artificially. So far 30 synthetic elements have been discovered—that is, synthesized...
member of Group 18. It has the highest atomic number and highest
atomic massThe atomic mass is the mass of a specific isotope, most often expressed in unified atomic mass units. The atomic mass is the total mass of protons, neutrons and electrons in a single atom....
of all the elements discovered so far.
The
radioactiveRadioactive decay is the process by which an atomic nucleus of an unstable atom loses energy by emitting ionizing particles . The emission is spontaneous, in that the atom decays without any physical interaction with another particle from outside the atom...
ununoctium atom is very unstable, and since 2002, only three atoms (possibly four) of the isotope have been detected. While this allowed for very little experimental characterization of its properties and possible
compoundsA chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
, theoretical calculations have resulted in many predictions, including some unexpected ones. For example, although ununoctium is a member of Group 18, it may possibly not be a
noble gasThe noble gases are a group of chemical elements with very similar properties: under standard conditions, they are all odorless, colorless, monatomic gases, with very low chemical reactivity...
, unlike all the other Group 18 elements. It was formerly thought to be a gas but is now predicted to be a
solidSolid is one of the three classical states of matter . It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a...
under
normal conditionsStandard condition for temperature and pressure are standard sets of conditions for experimental measurements established to allow comparisons to be made between different sets of data...
due to
relativistic effectsRelativistic quantum chemistry invokes quantum chemical and relativistic mechanical arguments to explain elemental properties and structure, especially for heavy elements of the periodic table....
.
Unsuccessful attempts
In late 1998, Polish physicist
Robert SmolańczukRobert Smolańczuk is a Polish theoretical physicist.He received his doctorate from the Soltan Institute for Nuclear Studies in 1996...
published calculations on the fusion of atomic nuclei towards the synthesis of superheavy atoms, including ununoctium. His calculations suggested that it might be possible to make ununoctium by fusing
leadLead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
with
kryptonKrypton is a chemical element with the symbol Kr and atomic number 36. It is a member of Group 18 and Period 4 elements. A colorless, odorless, tasteless noble gas, krypton occurs in trace amounts in the atmosphere, is isolated by fractionally distilling liquified air, and is often used with other...
under carefully controlled conditions.
In 1999, researchers at
Lawrence Berkeley National LaboratoryThe Lawrence Berkeley National Laboratory , is a U.S. Department of Energy national laboratory conducting unclassified scientific research. It is located on the grounds of the University of California, Berkeley, in the Berkeley Hills above the central campus...
made use of these predictions and announced the discovery of
ununhexiumUnunhexium is the temporary name of a synthetic superheavy element with the temporary symbol Uuh and atomic number 116. There is no proposed name yet although moscovium has been discussed in the media.It is placed as the heaviest member of group 16 although a sufficiently stable isotope is...
and ununoctium, in a paper published in
Physical Review LettersPhysical Review Letters , established in 1958, is a peer reviewed, scientific journal that is published 52 times per year by the American Physical Society...
, and very soon after the results were reported in
ScienceScience is the academic journal of the American Association for the Advancement of Science and is one of the world's top scientific journals....
. The researchers reported to have performed the
reactionIn nuclear physics and nuclear chemistry, a nuclear reaction is semantically considered to be the process in which two nuclei, or else a nucleus of an atom and a subatomic particle from outside the atom, collide to produce products different from the initial particles...
- + → + .
The following year, they published a retraction after researchers at other laboratories were unable to duplicate the results and the Berkeley lab itself was unable to duplicate them as well. 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 NinovVictor Ninov is a former researcher in the nuclear chemistry group at Lawrence Berkeley National Laboratory who was alleged to have fabricated the evidence used to claim the creation of ununoctium and ununhexium....
.
Discovery reports
The first decay of atoms of ununoctium was observed at the
Joint Institute for Nuclear ResearchThe Joint Institute for Nuclear Research, JINR , in Dubna, Moscow Oblast , Russia, is an international research centre for nuclear sciences, with 5500 staff members, 1200 researchers including 1000 Ph.D.s from eighteen member states The Joint Institute for Nuclear Research, JINR , in Dubna, Moscow...
(JINR) by
Yuri OganessianYuri Oganessian is a Russian nuclear physicist of Armenian descent. He and his team discovered the heaviest elements in the Periodic Table ....
and his group in
DubnaDubna is a town in Moscow Oblast, Russia. It has a status of naukograd , being home to the Joint Institute for Nuclear Research, an international nuclear physics research centre and one of the largest scientific foundations in the country. It is also home to MKB Raduga, a defence aerospace company...
, Russia, in 2002. On October 9, 2006, researchers from JINR and
Lawrence Livermore National LaboratoryThe Lawrence Livermore National Laboratory , just outside Livermore, California, is a Federally Funded Research and Development Center founded by the University of California in 1952...
of California, USA, working at the JINR in
DubnaDubna is a town in Moscow Oblast, Russia. It has a status of naukograd , being home to the Joint Institute for Nuclear Research, an international nuclear physics research centre and one of the largest scientific foundations in the country. It is also home to MKB Raduga, a defence aerospace company...
, announced that they had indirectly detected a total of three (possibly four) nuclei of ununoctium-294 (one or two in 2002 and two more in 2005) produced via collisions of
californiumCalifornium is a radioactive metallic chemical element with the symbol Cf and atomic number 98. The element was first made in the laboratory in 1950 by bombarding curium with alpha particles at the University of California, Berkeley. It is the ninth member of the actinide series and was the...
-249 atoms and
calcium-48Calcium-48 is a rare 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, the only radioactive decay pathway open to it is the extremely rare process of double beta decay...
ions:
- + → + 3 .
In 2011, the IUPAC has evaluated the 2006 results of the Dubna-Livermore collaboration and concluded that they did not meet the criteria for discovery.
Because of the very small fusion reaction probability (the fusion
cross sectionThe nuclear cross section of a nucleus is used to characterize the probability that a nuclear reaction will occur. The concept of a nuclear cross section can be quantified physically in terms of "characteristic area" where a larger area means a larger probability of interaction...
is ~0.3–0.6
pbA barn is a unit of area. Originally used in nuclear physics for expressing the cross sectional area of nuclei and nuclear reactions, today it is used in all fields of high energy physics to express the cross sections of any scattering process, and is best understood as a measure of the...
= (3–6)×10
−41 m
2) the experiment took 4 months and involved a beam dose of 4×10
19 calciumCalcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
ions that had to be shot at the
californiumCalifornium is a radioactive metallic chemical element with the symbol Cf and atomic number 98. The element was first made in the laboratory in 1950 by bombarding curium with alpha particles at the University of California, Berkeley. It is the ninth member of the actinide series and was the...
target to produce the first recorded event believed to be the synthesis of ununoctium. 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 100,000.
In the experiments, the alpha-decay of three atoms of ununoctium was observed. A fourth decay by direct
spontaneous fissionSpontaneous fission is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units , spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses...
was also proposed. A
half-lifeHalf-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 0.89 ms was calculated: decays into by
alpha decayAlpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle and thereby transforms into an atom with a mass number 4 less and atomic number 2 less...
. Since there were only three nuclei, the half-life derived from observed lifetimes has a large uncertainty: 0.89 ms.
- → +
The identification of the nuclei was verified by separately creating the putative
daughter nucleusIn nuclear physics, a decay product is the remaining nuclide left over from radioactive decay. Radioactive decay often involves a sequence of steps...
by means of a bombardment of with ions,
- + → + 3 ,
and checking that the decay matched the
decay chainIn nuclear science, the decay chain refers to the radioactive decay of different discrete radioactive decay products as a chained series of transformations...
of the nuclei. The daughter nucleus is very unstable, decaying with a half-life of 14 milliseconds into , which may experience either
spontaneous fissionSpontaneous fission is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units , spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses...
or alpha decay into , which will undergo spontaneous fission.
In a quantum-tunneling model, the alpha decay half-life of
294Uuo was predicted to be 0.66 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 low but comparable results.
Following the success in obtaining ununoctium, the discoverers have started similar experiments in the hope of creating
unbiniliumUnbinilium , also called eka-radium or element 120, is the temporary, systematic element name of a hypothetical chemical element in the periodic table that has the temporary symbol Ubn and has the atomic number 120....
from and .
Isotopes of unbinilium are predicted to have alpha decay half-lives of the order of micro-seconds.
Target-projectile combinations leading to Z=118 compound nuclei
| Target | Projectile | CN | Attempt result |
| 208Pb |
86Kr |
293Uuo |
|
| 249Cf |
48Ca |
294Uuo |
|
Naming
Until the 1960s ununoctium was known as
eka-emanation (emanation is the old name for radon). In 1979 the IUPAC published recommendations according to which the element was to be called
ununoctium, a
systematic element nameA systematic element name is the temporary name and symbol assigned to newly synthesized and not yet synthesized chemical elements. In chemistry, a transuranic element receives a permanent name and symbol only after its synthesis has been confirmed. In some cases, this has been a protracted and...
, as a
placeholderPlaceholder names are words that can refer to objects or people whose names are either temporarily forgotten, irrelevant, or unknown in the context in which they are being discussed...
until the discovery of the element is confirmed and the IUPAC decides on a name.
Before the retraction in 2002, the researchers from Berkeley had intended to name the element
ghiorsium (Gh), after
Albert GhiorsoAlbert Ghiorso was an American nuclear scientist and co-discoverer of a record 12 chemical elements on the periodic table. His research career spanned five decades, from the early 1940s to the late 1990s.-Early life:...
(a leading member of the research team).
The Russian discoverers reported their synthesis in 2006. In 2007, the head of the Russian institute stated the team were considering two names for the new element:
flyorium in honor of
Georgy FlyorovGeorgy Nikolayevich Flyorov was a prominent Soviet nuclear physicist.-Biography:Flyorov was born in Rostov-on-Don and attended the Leningrad Polytechnic Institute Georgy Nikolayevich Flyorov (March 2, 1913 – November 19, 1990) was a prominent Soviet nuclear physicist.-Biography:Flyorov was born...
, the founder of the research laboratory in Dubna; and
moskovium, in recognition of the
Moskovskaya OblastMoscow Oblast , or Podmoskovye , is a federal subject of Russia . Its area, at , is relatively small compared to other federal subjects, but it is one of the most densely populated regions in the country and, with the 2010 population of 7,092,941, is the second most populous federal subject...
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. However, these names were later proposed for
element 114Ununquadium is the temporary name of a radioactive chemical element with the temporary symbol Uuq and atomic number 114. There is no proposed name yet, although flerovium has been discussed in the media.About 80 decays of atoms of...
(flerovium) and
element 116Ununhexium is the temporary name of a synthetic superheavy element with the temporary symbol Uuh and atomic number 116. There is no proposed name yet although moscovium has been discussed in the media.It is placed as the heaviest member of group 16 although a sufficiently stable isotope is...
(moscovium).
Nucleus stability and isotopes
There are no elements with an
atomic numberIn chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element...
above 82 (after
leadLead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
) that have stable isotopes. The stability of nuclei decreases with the increase in atomic number, such that all isotopes with an atomic number above
101Mendelevium is a synthetic element with the symbol Md and the atomic number 101. A metallic radioactive transuranic element in the actinide series, mendelevium is usually synthesized by bombarding einsteinium with alpha particles. It was named after Dmitri Ivanovich Mendeleev, who created the...
decay radioactivelyRadioactive decay is the process by which an atomic nucleus of an unstable atom loses energy by emitting ionizing particles . The emission is spontaneous, in that the atom decays without any physical interaction with another particle from outside the atom...
with a
half-lifeHalf-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
under a day, with an exception of
268Db. Nevertheless, because of
reasonsIn nuclear physics, a magic number is a number of nucleons such that they are arranged into complete shells within the atomic nucleus...
not very well understood yet, there is a slight increased nuclear stability around atomic numbers 110–114, which leads to the appearance of what is known in nuclear physics as the "
island of stabilityThe island of stability in nuclear physics describes a set of as-yet undiscovered isotopes of transuranium elements which are theorized to be much more stable than others...
". This concept, proposed by UC Berkeley professor Glenn Seaborg, explains why superheavy elements last longer than predicted. Ununoctium is radioactive and has
half-lifeHalf-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
that appears to be less than a
millisecondA millisecond is a thousandth of a second.10 milliseconds are called a centisecond....
. Nonetheless, this is still longer than some predicted values, thus giving further support to the idea of this "island of stability".
Calculations using a quantum-tunneling model predict the existence of several neutron-rich isotopes of ununoctium with alpha-decay half-lives close to 1 ms.
Theoretical calculations done on the synthetic pathways for, and the half-life of, other
isotopesUnunoctium is an artificial element, and thus a standard atomic mass cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 294Uuo in 2006. All data is hypothetical...
have shown that some could be slightly more
stableStable isotopes are chemical isotopes that may or may not be radioactive, but if radioactive, have half-lives too long to be measured.Only 90 nuclides from the first 40 elements are energetically stable to any kind of decay save proton decay, in theory...
than the synthesized isotope , most likely , , , , , and . Of these, might provide the best chances for obtaining longer-lived nuclei, and thus might become the focus of future work with this element. Some isotopes with many more neutrons, such as some located around , could also provide longer-lived nuclei.
Calculated atomic and physical properties
Ununoctium is a member of group 18, the zero-valence elements. The members of this group are usually inert to most common chemical reactions (for example, combustion) because the outer valence shell is completely filled with
eight electronsThe octet rule is a chemical rule of thumb that states that atoms of low The octet rule is a chemical rule of thumb that states that atoms of low The octet rule is a chemical rule of thumb that states that atoms of low (The octet rule is a chemical rule of thumb that states that atoms of low (...
. This produces a stable, minimum energy configuration in which the outer electrons are tightly bound. It is thought that similarly, ununoctium has a closed outer valence shell in which its
valence electronIn chemistry, valence electrons are the electrons of an atom that can participate in the formation of chemical bonds with other atoms. Valence electrons are the "own" electrons, present in the free neutral atom, that combine with valence electrons of other atoms to form chemical bonds. In a single...
s are arranged in a 7s
27p
6 configurationIn atomic physics and quantum chemistry, electron configuration is the arrangement of electrons of an atom, a molecule, or other physical structure...
.
Consequently, some expect ununoctium to have similar physical and chemical properties to other members of its group, most closely resembling the noble gas above it in the periodic table,
radonRadon is a chemical element with symbol Rn and atomic number 86. It is a radioactive, colorless, odorless, tasteless noble gas, occurring naturally as the decay product of uranium or thorium. Its most stable isotope, 222Rn, has a half-life of 3.8 days...
.
Following the periodic trend, ununoctium would be expected to be slightly more reactive than radon. However, theoretical calculations have shown that it could be quite reactive, so that it can probably not be considered a noble gas. In addition to being far more reactive than radon, ununoctium may be even more reactive than elements
ununquadiumUnunquadium is the temporary name of a radioactive chemical element with the temporary symbol Uuq and atomic number 114. There is no proposed name yet, although flerovium has been discussed in the media.About 80 decays of atoms of...
and copernicium. The reason for the apparent enhancement of the chemical activity of ununoctium relative to radon is an energetic destabilization and a radial expansion of the last occupied 7p subshell. More precisely, considerable spin–orbit interactions between the 7p electrons with the inert 7s
2 electrons, effectively lead to a second valence shell closing at
ununquadiumUnunquadium is the temporary name of a radioactive chemical element with the temporary symbol Uuq and atomic number 114. There is no proposed name yet, although flerovium has been discussed in the media.About 80 decays of atoms of...
, and a significant decrease in stabilization of the closed shell of element 118. It has also been calculated that ununoctium, unlike other noble gases, binds an electron with release of energy—or in other words, it exhibits positive
electron affinityThe Electron affinity of an atom or molecule is defined as the amount of energy released when an electron is added to a neutral atom or molecule to form a negative ion....
.
Ununoctium is expected to have by far the broadest
polarizabilityPolarizability is the measure of the change in a molecule's electron distribution in response to an applied electric field, which can also be induced by electric interactions with solvents or ionic reagents. It is a property of matter...
of all elements before it in the periodic table, and almost twofold of radon. By extrapolating from the other noble gases, it is expected that ununoctium has a boiling point between 320 and 380 K. This is very different from the previously estimated values of 263 K or 247 K. Even given the large uncertainties of the calculations, it seems highly unlikely that ununoctium would be a gas under standard conditions. And as the liquid range of the other gases is very narrow, between 2 and 9 kelvins, this element should be
solidSolid is one of the three classical states of matter . It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a...
at standard conditions. If ununoctium forms a
gasGas is one of the three classical states of matter . Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons...
under standard conditions nevertheless, it would be one of the densest gaseous substances at standard conditions (even if it is monatomic like the other noble gases).
Because of its tremendous polarizability, ununoctium is expected to have an anomalously low
ionization energyThe ionization energy of a chemical species, i.e. an atom or molecule, is the energy required to remove an electron from the species to a practically infinite distance. Large atoms or molecules have a low ionization energy, while small molecules tend to have higher ionization energies.The property...
(similar to that of
leadLead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
which is 70% of that of radon and significantly smaller than that of ununquadium) and a standard state condensed phase.
Predicted compounds
No compounds of ununoctium have been synthesized yet, but calculations on
theoretical compoundsTheoretical chemistry seeks to provide theories that explain chemical observations. Often, it uses mathematical and computational methods that, at times, require advanced knowledge. Quantum chemistry, the application of quantum mechanics to the understanding of valency, is a major component of...
have been performed since 1964. It is expected that if the
ionization energyThe ionization energy of a chemical species, i.e. an atom or molecule, is the energy required to remove an electron from the species to a practically infinite distance. Large atoms or molecules have a low ionization energy, while small molecules tend to have higher ionization energies.The property...
of the element is high enough, it will be difficult to oxidize and therefore, the most common
oxidation stateIn chemistry, the oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound. The formal oxidation state is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. Oxidation states are typically represented by...
will be 0 (as for other noble gases).
Calculations on the dimeric
moleculeA molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
showed a
bondingA chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The bond is caused by the electromagnetic force attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction...
interaction roughly equivalent to that calculated for , and a dissociation energy of 6 kJ/mol, roughly 4 times of that of . But most strikingly, it was calculated to have a
bond length- Explanation :Bond length is related to bond order, when more electrons participate in bond formation the bond will get shorter. Bond length is also inversely related to bond strength and the bond dissociation energy, as a stronger bond will be shorter...
shorter than in by 0.16 Å, which would be indicative of a significant bonding interaction. On the other hand, the compound UuoH
+ exhibits a dissociation energy (in other words
proton affinityThe proton affinity, Epa, of an anion or of a neutral atom or molecule is a measure of its gas-phase basicity. It is the energy released in the following reactions:-Acid/base chemistry:...
of Uuo) that is smaller than that of RnH
+.
The bonding between ununoctium and
hydrogenHydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
in UuoH is very limp and can be regarded as a pure van der Waals interaction rather than a true
chemical bondA chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The bond is caused by the electromagnetic force attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction...
. On the other hand, with highly electronegative elements, ununoctium seems to form more stable compounds than for example copernicium or
ununquadiumUnunquadium is the temporary name of a radioactive chemical element with the temporary symbol Uuq and atomic number 114. There is no proposed name yet, although flerovium has been discussed in the media.About 80 decays of atoms of...
. The stable oxidation states +2 and +4 have been predicted to exist in the
fluorFluor Corporation is a publicly owned engineering, procurement, construction, and maintenance services organization. Fluor is headquartered in the Las Colinas area of Irving, Texas. The company employs more than 41,000 international employees and maintains offices in over 25 countries...
inated compounds and . This is a result of the same spin-orbit interactions that make ununoctium unusually reactive. For example, it was shown that the reaction of Uuo with to form the compound , would release an energy of 106 kcal/mol of which about 46 kcal/mol come from these interactions. For comparison, the spin-orbit interaction for the similar molecule is about 10 kcal/mol out of a formation energy of 49 kcal/mol. The same interaction stabilizes the
tetrahedral Td configurationIn a tetrahedral molecular geometry a central atom is located at the center with four substituents that are located at the corners of a tetrahedron. The bond angles are cos−1 ≈ 109.5° when all four substituents are the same, as in CH4. This molecular geometry is common throughout the first...
for , as distinct from the
square planar D4h oneThe square planar molecular geometry in chemistry describes the stereochemistry that is adopted by certain chemical compounds...
of
Xenon tetrafluoride is a chemical compound with chemical formula . It was the first discovered binary compound of a noble gas. It is produced by the chemical reaction of xenon with fluorine, , according to the chemical equation:...
and . The Uuo–F bond will most probably be
ionicAn ionic bond is a type of chemical bond formed through an electrostatic attraction between two oppositely charged ions. Ionic bonds are formed between a cation, which is usually a metal, and an anion, which is usually a nonmetal. Pure ionic bonding cannot exist: all ionic compounds have some...
rather than
covalentA covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding....
, rendering the UuoF
n compounds non-volatile. Unlike the other noble gases, ununoctium was predicted to be sufficiently electropositive to form a Uuo–Cl bond with
chlorineChlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
.
Since no more than four atoms of ununoctium have been produced, it currently has no uses outside of
basic scientific researchBasic Research is an herbal supplement and cosmetics manufacturer based in Salt Lake City, Utah that distributes products through a large number of subsidiaries. In addition, their products are sold domestically and internationally through a number of high-end retailers. Dennis Gay is the...
.
See also
- Transactinide element
In chemistry, transactinide elements are the chemical elements with atomic numbers greater than those of the actinides, the heaviest of which is lawrencium ....
- Transuranic element
- Ununhexium
Ununhexium is the temporary name of a synthetic superheavy element with the temporary symbol Uuh and atomic number 116. There is no proposed name yet although moscovium has been discussed in the media.It is placed as the heaviest member of group 16 although a sufficiently stable isotope is...
External links
- Element 118: experiments on discovery, archive of discoverers' official web page
- Chemistry Blog: Independent analysis of 118 claim
- WebElements: Ununoctium
- It's Elemental: Ununoctium
- On the Claims for Discovery of Elements 110, 111, 112, 114, 116, and 118 (IUPAC Technical Report)
- "Element 118, Heaviest Ever, Reported for 1,000th of a Second", NYTimes.com.
- Eric Scerri, The Periodic Table, Its Story and Its Significance, Oxford University Press, New York, 2007.