Periodic Table > Ununoctium


Some elements exist in several different structural forms, called allotropes. Each allotrope has different physical properties.

For more information on the Visual Elements image see the Uses and properties section below.



A vertical column in the periodic table. Members of a group typically have similar properties and electron configurations in their outer shell.

A horizontal row in the periodic table. The atomic number of each element increases by one, reading from left to right.

Elements are organised into blocks by the orbital type in which the outer electrons are found. These blocks are named for the characteristic spectra they produce: sharp (s), principal (p), diffuse (d), and fundamental (f).

Atomic number
The number of protons in an atom.

Electron configuration
The arrangements of electrons above the last (closed shell) noble gas.

Melting point
The temperature at which the solid–liquid phase change occurs.

Boiling point
The temperature at which the liquid–gas phase change occurs.

The transition of a substance directly from the solid to the gas phase without passing through a liquid phase.

Density (g cm−3)
Density is the mass of a substance that would fill 1 cm3 at room temperature.

Relative atomic mass
The mass of an atom relative to that of carbon-12. This is approximately the sum of the number of protons and neutrons in the nucleus. Where more than one isotope exists, the value given is the abundance weighted average.

Atoms of the same element with different numbers of neutrons.

CAS number
The Chemical Abstracts Service registry number is a unique identifier of a particular chemical, designed to prevent confusion arising from different languages and naming systems.

Fact box

Group 18  Melting point Unknown 
Period Boiling point Unknown 
Block Density (g cm−3) Unknown 
Atomic number 118  Relative atomic mass [294]  
State at 20°C Solid  Key isotopes 294Uuo 
Electron configuration [Rn] 5f146d107s27p6  CAS number 54144-19-3 
ChemSpider ID - ChemSpider is a free chemical structure database


Image explanation

Murray Robertson is the artist behind the images which make up Visual Elements. This is where the artist explains his interpretation of the element and the science behind the picture.


The description of the element in its natural form.

Biological role

The role of the element in humans, animals and plants.

Natural abundance

Where the element is most commonly found in nature, and how it is sourced commercially.

Uses and properties

Image explanation
There’s no Visual Elements image for this element yet as claims for its discovery are currently being considered by the IUPAC/IUPAP Joint Working Party.
A highly radioactive metal, of which only a few atoms have ever been made.
At present, it is only used in research.
Biological role
It has no known biological role.
Natural abundance

Atomic radius, non-bonded
Half of the distance between two unbonded atoms of the same element when the electrostatic forces are balanced. These values were determined using several different methods.

Covalent radius
Half of the distance between two atoms within a single covalent bond. Values are given for typical oxidation number and coordination.

Electron affinity
The energy released when an electron is added to the neutral atom and a negative ion is formed.

Electronegativity (Pauling scale)
The tendency of an atom to attract electrons towards itself, expressed on a relative scale.

First ionisation energy
The minimum energy required to remove an electron from a neutral atom in its ground state.

Atomic data

Atomic radius, non-bonded (Å) Unknown Covalent radius (Å) 1.57
Electron affinity (kJ mol−1) 5.403 Electronegativity
(Pauling scale)
Ionisation energies
(kJ mol−1)


Data for this section been provided by the British Geological Survey.

Relative supply risk

An integrated supply risk index from 1 (very low risk) to 10 (very high risk). This is calculated by combining the scores for crustal abundance, reserve distribution, production concentration, substitutability, recycling rate and political stability scores.

Crustal abundance (ppm)

The number of atoms of the element per 1 million atoms of the Earth’s crust.

Recycling rate

The percentage of a commodity which is recycled. A higher recycling rate may reduce risk to supply.


The availability of suitable substitutes for a given commodity.
High = substitution not possible or very difficult.
Medium = substitution is possible but there may be an economic and/or performance impact
Low = substitution is possible with little or no economic and/or performance impact

Production concentration

The percentage of an element produced in the top producing country. The higher the value, the larger risk there is to supply.

Reserve distribution

The percentage of the world reserves located in the country with the largest reserves. The higher the value, the larger risk there is to supply.

Political stability of top producer

A percentile rank for the political stability of the top producing country, derived from World Bank governance indicators.

Political stability of top reserve holder

A percentile rank for the political stability of the country with the largest reserves, derived from World Bank governance indicators.



Common oxidation states

The oxidation state of an atom is a measure of the degree of oxidation of an atom. It is defined as being the charge that an atom would have if all bonds were ionic. Uncombined elements have an oxidation state of 0. The sum of the oxidation states within a compound or ion must equal the overall charge.


Atoms of the same element with different numbers of neutrons.

Key for isotopes

Half life
  y years
  d days
  h hours
  m minutes
  s seconds
Mode of decay
  α alpha particle emission
  β negative beta (electron) emission
  β+ positron emission
  EC orbital electron capture
  sf spontaneous fission
  ββ double beta emission
  ECEC double orbital electron capture

Oxidation states and isotopes

Common oxidation states Unknown
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  294Uuo 294 - 0.9 s  α 


Specific heat capacity (J kg−1 K−1)

Specific heat capacity is the amount of energy needed to change the temperature of a kilogram of a substance by 1 K.

Young's modulus

A measure of the stiffness of a substance. It provides a measure of how difficult it is to extend a material, with a value given by the ratio of tensile strength to tensile strain.

Shear modulus

A measure of how difficult it is to deform a material. It is given by the ratio of the shear stress to the shear strain.

Bulk modulus

A measure of how difficult it is to compress a substance. It is given by the ratio of the pressure on a body to the fractional decrease in volume.

Vapour pressure

A measure of the propensity of a substance to evaporate. It is defined as the equilibrium pressure exerted by the gas produced above a substance in a closed system.

Pressure and temperature data – advanced

Specific heat capacity
(J kg−1 K−1)
Unknown Young's modulus (GPa) Unknown
Shear modulus (GPa) Unknown Bulk modulus (GPa) Unknown
Vapour pressure  
Temperature (K)
400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
Pressure (Pa)
- - - - - - - - - - -
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Listen to Ununoctium Podcast
Transcript :

Chemistry in its element: element 118


You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry.

(End promo)

Meera Senthilingam

This week the chemist's that are seeking fame. Here's Andrea Sella.

Andrea Sella

We live in an age when everyone is just gagging to be 'famous'. Andy Warhol, of course, pointed out that everyone was likely to be famous for 15 minutes. But the real question is, if you're a chemist, or a scientist generally, what does it take to become famous? How do earn the adulation of the masses? And if not the masses, at least of your peers?

You'd think a Nobel prize would do it. But you'd be surprised how few of them anyone can actually remember, apart from a few early 20th century heroes. And to have an element named after you need to be dead. So that seems quite pointless.

What if you discovered a new element? For about 70 years, ever since plutonium slipped out of a nuclear reaction, the search has been on to make ever heavier and more exotic elements to add to our periodic table. And I emphasise the word 'make' because it is no longer a question of finding a rock and extracting from it some mysterious substance that does not fit the description of anything that has come before. No, you actually have to make it from scratch.

So how do you make an element? Well new atoms of, admittedly old, elements, are being made all the time. Nuclear fusion of hydrogen is the fundamental process that powers stars. But as stars age and steadily run out of hydrogen they gradually start fusing heavier nuclei and it is then possible to make ever heavier atoms. It's brutally difficult because you have to get past the huge positive charges of the two nuclei to get them to fuse. Stars can do this nucleosynthesis up to iron. Unfortunately that's where things end.

After that the way to make anything heavier is by adding neutrons. Because the neutron has no charge it can sneak quietly into the nucleus. The neutron can then add to the total mass count, and the nucleus can then decay by spitting out an electron to give you something that is one place higher along in the periodic table. And repeating this process laboriously - one step forward, one step back - will take you all the way out towards uranium, which at atomic number 92 is about as high as one can find lying around in universe.

But can one go beyond? The answer turns out to be yes. Teams in the US, Germany, Japan and Russia have been hard at work doing it. And the process is incredibly difficult. Essentially what they do is strip atoms down to their nuclei and then accelerate them to phenomenal speeds using a particle accelerator, and then slam these ions into a target. So for example the element lawrencium was made by bashing a californium target with naked boron nuclei.

This is not work for the lone experimenter working in a shed somewhere. These are experiments of extraordinary subtlety and complexity. And the problem is not just making the new element but also figuring out what you've got at the end. The problem is that you only make a few atoms at a time and these products tend to be spectacularly unstable so you sometimes have only a few milliseconds in which to work out what you've got. It's complex. It's expensive. And very, very clever. And each new atom really is a whole new chemical world to explore. Can it be any wonder that it attracts fortune seekers?

In June 1999 the Lawrence Berkeley Lab in California, one of the few places in the world that does this sort of work announced in the journal Physical Review Letters that they had succeeded in making ununhexium and ununoctium, which in plain English means elements 116 and 118, by bashing a lead target with krypton nuclei. Huge excitement followed because these were by far the heaviest elements ever made. It seemed a real breakthrough. The method they had used was also a departure from previous work - a new strategy that had gone spectacularly well. The secretary of energy, whose department had funded the work noted that four of the senior members of the team were foreign said 'this stunning discovery which opens the door to further insights into the structure of the atomic nucleus also underscores the value of foreign visitors and what the country would lose if there were a moratorium on foreign visitors at our national labs. Scientific excellence doesn't recognise national boundaries, and we will damage our ability to perform world-class science if we cut off our laboratories from the rest of the world.'

The problem was however, that no one else could repeat the work. Labs in Germany and Russia reported that they got different results. A major process of soul-searching started in California and the data began to be picked over in great detail. A painful investigation concluded that one of the team leaders Victor Ninov, a Bulgarian national, had fabricated the crucial data. Confronted with the evidence, Ninov denied everything. But in Germany, irregularities came to light in the data associated with an earlier discovery he had been involved with - that of elements 111 and 112. Ninov was fired. The Berkeley led group were then forced to do the unthinkable - to publish a retraction, the author list being one name shorter than the original paper. It was the scientific equivalent of hara kiri.

But did element 116 really not exist? In 2000, the rival group in Russia reported having made a single atom of element 116 and within 3 years had succeeded in making more atoms of two different isotopes of this element. 118, on the other hand, had to wait until 2002 for successful synthesis by a route that differed from that used by the Americans. So 116 and 118 are real, and their properties are slowly being mapped out even as we speak. But does anyone remember the names of the people who are the rightful discoverers? Does the name Oganessian ring a bell? Probably not.

It's more likely that you remember the name of Victor Ninov, the man at the centre of the storm. Perverse, isn't it? But it's the way of the world. Fame, even in science, is a fickle mistress.

Meera Senthilingam

Perhaps the net aim then, rather than finding an element could be to find a way to preserve these legacies. Just a thought. That was University College London's Andrea Sella with the fundamental not famous chemistry of elements 116 and 118. Now next week a two faced element.

David Read

Sodium, like most elements in the periodic table could be said to have a dual personality. On one side it is an essential nutrient for most living things, and yet, due to its reactive nature is also capable of wreaking havoc if you happen to combine it with something you shouldn't.

As such sodium is found naturally only in compounds and never as the free element. Even so it is highly abundant, accounting for around 2.6 per cent of the earths crust by weight.

Meera Senthilingam

And to find out some of the beneficial, as well as lethal roles of sodium - as well as the mystery behind it being given the symbol Na, join David Read from the University of Southampton in next week's Chemistry in its element.


Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by There's more information and other episodes of Chemistry in its element on our website at

(End promo)
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A teaching resource on the noble gases, supported by video clips from the Royal Institution Christmas Lectures® 2012.
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Visual Elements images and videos
© Murray Robertson 2011.



W. M. Haynes, ed., CRC Handbook of Chemistry and Physics, CRC Press/Taylor and Francis, Boca Raton, FL, 95th Edition, Internet Version 2015, accessed December 2014.
Tables of Physical & Chemical Constants, Kaye & Laby Online, 16th edition, 1995. Version 1.0 (2005), accessed December 2014.
J. S. Coursey, D. J. Schwab, J.J. Tsai, and R. A. Dragoset, Atomic Weights and Isotopic Compositions(version 3.0), 2010, National Institute of Standards and Technology, Gaithersburg, MD, accessed December 2014.
T. L. Cottrell, The Strengths of Chemical Bonds, Butterworth, London, 1954.


Uses and properties

John Emsley, Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, New York, 2nd Edition, 2011.
Thomas Jefferson National Accelerator Facility - Office of Science Education, It’s Elemental - The Periodic Table of Elements, accessed December 2014.
Periodic Table of Videos, accessed December 2014.


Supply risk data

Derived in part from material provided by the British Geological Survey © NERC.


History text

© John Emsley 2012.



Produced by The Naked Scientists.


Periodic Table of Videos

Created by video journalist Brady Haran working with chemists at The University of Nottingham.
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