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 Melting point Unknown 
Period Boiling point Unknown 
Block Density (g cm−3) Unknown 
Atomic number 107  Relative atomic mass [270]  
State at 20°C Solid  Key isotopes 272Bh 
Electron configuration [Rn] 5f146d57s2  CAS number 54037-14-8 
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
The abstracted symbol and patterns are based on the, now iconic, atomic model proposed by Niels Bohr in 1913.
Bohrium is a highly radioactive metal.
At present, bohrium is of research interest only.
Biological role
Bohrium has no known biological role.
Natural abundance
Bohrium does not occur naturally and only a few atoms have ever been made. It will probably never be isolated in observable quantities. It was created by the so-called ‘cold fusion’ method. This involved the bombardment of bismuth with atoms of chromium.
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In 1975 a team led by Yuri Oganessian at the Russian Joint Institute for Nuclear Research (JINR) in Dubna, bombarded bismuth with chromium and produced element 107, isotope-261. They published the results of their successful run in 1976 and submitted a discovery claim.

In 1981, a team led by Peter Armbruster and Gottfried Münzenberg at the German nuclear research institute the Geselleschaft für Schwerionenforschung (GSI) bombarded bismuth with chromium and they succeeded in making a single atom of isotope 262. Now followed a period of negotiation to establish who discovered elements 107 first and thereby had the right to name it.

The International Union of Pure and Applied Chemistry (IUPAC) said that the GSI should be awarded the discovery because they had the more credible submission, but that the JINR were probably the first to make it.

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) 1.41
Electron affinity (kJ mol−1) Unknown Electronegativity
(Pauling scale)
Ionisation energies
(kJ mol−1)


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
  272Bh 272.138 - ~ 10 s  α 


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.



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 Bohrium Podcast
Transcript :

Chemistry in its element: bohrium


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 we are fusing nuclei. Erric Scerri.

Eric Scerri

A total of 25 transuranium elements have now been artificially synthesised, starting with neptunium element 93 and ending with the as yet unnamed element 118. This includes the most recently announced element of all, element 117 that was synthesised in April 2010.

This podcast is about one of these elements, number 107 in the periodic table, called bohrium. Transuranium elements are essentially made by slamming atoms of different elements into each other at very high speeds in the hope that such collisions will allow nuclei to fuse together to form atoms of a new element.

The few atoms that ever form in this way are very unstable and typically decay with half-lives of seconds or fractions of a second. Lay persons often wonder why such experiments are important since practical applications of the elements that are man-made are generally out of the question. The answer is that the experiments are of scientific importance since they allow one to verify theoretical predictions. Element 107 has had a special role to play in this respect and I will return to this in a moment.

Bohrium is also special in another respect, as the first element to be synthesised by a cold - rather than hot - fusion process between two nuclei. The idea is to make two nuclei collide at low excitation energies and consequently to capitalise on the reduced tendency of such combined atoms to disintegrate. Incidentally, this kind of cold fusion has no connection to the alleged cold-fusion that was announced in 1989 by Martin Fleischmann and Stanley Pons who reported that they had produced fusion in a tabletop experiment using heavy water.

The successful cold fusion synthesis of bohrium was first achieved in 1981 in Darmstadt, Germany, by the fusion of bismuth-209 with chromium-24 to form bohrium-262 with a half life of about 85 milliseconds. Since then many other isotopes of bohrium have been produced, including the longest lived isotope so far bohrium-270, with a half life of 61 seconds.

The element's discoverers wanted to call it nielsbohrium after the great 20th century Danish physicist. But Iupac, the official body that governs the naming of elements, ruled against this name on the grounds that no element had ever been given the full name of a scientist. Instead they proposed bohrium, which became the officially recognised name in 1997.

In the periodic table bohrium lies below chromium, technetium and rhenium in group 6. However, the application of the theory of relativity to calculations involving very heavy atoms like bohrium leads to predictions of anomalous behaviour which suggests that they do not behave as typical members of the groups that they lie in. For example, the discovery of elements 104 and 105, rutherfordium and dubnium respectively, and chemical experiments conducted on them, strongly suggested that relativistic effects were causing these elements to behave in anomalous ways and not as expected according to their places in the periodic table. It began to look as if the periodic law, of which the periodic table is a graphic representation, had met its match.

It was only when the chemistry of elements 106 and 107, or seaborgium and bohrium respectively, were examined that it became clear that the periodic law was not being over-turned by relativistic effects. Quantitative experiments on the properties of the oxychloride of bohrium, in particular, showed that the element was behaving almost exactly that one would have predicted from its position below technetium and rhenium in the periodic table. In fact an article describing the chemistry of bohrium that appeared in the journal Nature with the title 'Boring bohrium', referring to the fact that bohrium was behaving as expected and not showing the exotic signs of relativistic effects.

It is quite remarkable that the periodic law that was discovered over 140 years ago has not been overturned by quantum mechanics or by the theory of relativity which date from more recent times and which one might suppose to have penetrated into the secrets of nature to a greater degree. Or perhaps it is just that the phenomenon of chemical periodicity as embodied by the periodic table represents a completely universal and fundamental principle of nature.

Meera Senthilingam

So the impressive accuracy of chemical periodicity. That was UCLA scientist and author Eric Scerri with the lawful chemistry of bohrium. Now next week we flash back to a memorable decade.

Anna Lewcock

Do you remember the 80s? The leg warmers, the big hair, the shoulder pads? Many fashion crimes were committed and statements made as a generation fought to carve out its identity.

Looking back on those photos a couple of decades down the line, some might wish they hadn't fought so hard. But it's not just rebellious teenagers or disillusioned 40-somethings that suffer identity crises - elements can too.

Meera Senthilingam

And to discover the crises that face the element hassium join the RSC's Anna Lewcock in next week's Chemistry in its element. Until then thank you for listening, I'm Meera Senthilingam.


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

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Visual Elements images and videos
© Murray Robertson 1998-2017.



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 4.1), 2015, National Institute of Standards and Technology, Gaithersburg, MD, accessed November 2016.
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

Elements 1-112, 114, 116 and 117 © John Emsley 2012. Elements 113, 115, 117 and 118 © Royal Society of Chemistry 2017.



Produced by The Naked Scientists.


Periodic Table of Videos

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