Glossary
Allotropes
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.
| Discovery date | 1898 |
| Discovered by | Pierre and Marie Curie |
| Origin of the name | The name is derived from the Latin 'radius', meaning ray. |
| Allotropes |
|
Glossary
Group
A vertical column in the periodic table. Members of a group typically have similar properties and electron configurations in their outer shell.
Period
A horizontal row in the periodic table. The atomic number of each element increases by one, reading from left to right.
Block
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.
Sublimation
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.
Isotopes
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.
| Group | 2 | Melting point | 696°C, 1285°F, 969 K |
| Period | 7 | Boiling point | 1500°C, 2732°F, 1773 K |
| Block | s | Density (g cm−3) | 5 |
| Atomic number | 88 | Relative atomic mass | [226] |
| State at 20°C | Solid | Key isotopes | 226Ra |
| Electron configuration | [Rn] 7s2 | CAS number | 7440-14-4 |
| ChemSpider ID | 4886483 | ChemSpider is a free chemical structure database | |
Glossary
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.
Appearance
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.
History
History
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.
Glossary
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.
Isotopes
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 | |
Glossary
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.
Substitutability
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.
|
|
Glossary
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.
Podcasts
Podcasts
| Listen to Radium Podcast |
|
Transcript :
Chemistry in its element: radium (Promo) You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry. (End promo) Chris Smith Hello, this week the self illuminating story of element number 88. Here's Brian Clegg. Brian Clegg There's something about Radium that is deliciously Victorian. It's not just that this radioactive element was discovered at the end of the Victorian era in 1898. There's also something about its early use as a universal restorative that has a peculiarly period feel. It was seen as a source of energy and brightness, it was included in toothpastes and quack potions - it was even rubbed into the scalp as a hair restorer. But the application of radium that would bring it notoriety was its use in glow-in-the-dark paint. Frequently used to provide luminous readouts on clocks and watches, aircraft switches and instrument dials, the eerie blue glow of radium was seen as a harmless, practical source of night time illumination. It was only when a number of the workers who painted the luminous dials began to suffer from sores, anaemia and cancers around the mouth that it was realized that something was horribly wrong. The women workers would regularly bring their paintbrushes to a point by licking them. This left enough radioactive residue in their mouths to cause cell damage. Eventually over 100 of the workers would die from the effects. A more famous victim of radium was its discoverer, the double Nobel prize winner Marie Curie, born Maria Sklodowska. Working with her husband Pierre, Marie Curie was studying pitchblende, a mineral from North Bohemia that contained uranium. Pitchblende was mined near what's now Jachymov in the Czech Republic, and after the uranium had been extracted to be used to colour pottery glazes and tint photographs, the residual slag was dumped in a nearby forest. Without the uranium, the pitchblende proved still to be radioactive - in fact whatever the other radioactive material was, it was much more radioactive than the uranium itself. Marie Curie wrote to sister Bronia that 'The radiation that I couldn't explain comes from a new chemical element. The element is there and I've got to find it! We are sure!' After working through tonnes of the pitchblende slag, the Curies identified two new elements in the remaining material - polonium and radium. They finally isolated radium in 1902 in its pure metal form. Radium was named for the Latin for a ray and proved to be the most radioactive natural substance ever discovered. Although Marie Curie lived until 1934, her death from aplastic anaemia is almost certainly due to her exposure to radioactive materials, particularly radium. To this day her notebooks and papers have to be kept in lead lined boxes and handled with protective clothing, as they remain radioactive. Radium occurs naturally as uranium decays - though only in very small quantities. It took many tonnes of pitchblende to produce the tenth of a gram of radium that the Curies eventually extracted. It's classified in the periodic table as an alkaline earth metal - the heaviest of the series - putting it alongside more familiar metals like magnesium and calcium. With atomic number 88, it has four natural isotopes of atomic weight 228, 226, 224 and 223 - though there are a remarkable 21 more artificial isotopes. A later starring role for radium would be as the source of alpha particles - helium nuclei - used by Rutherford in 1909 at the Cavendish laboratory in Cambridge to fire at a thin gold foil. Radium decays to radon, throwing out an alpha particle from its nucleus. Unexpectedly, Rutherford's assistants Hans Geiger and Ernest Marsden found that a very few of the alpha particles bounced back - Rutherford likened it to 'firing a 15 inch shell at a piece of tissue paper and having it come back and hit you.' This behaviour was used to deduce the existence of a compact, dense nucleus in the atom - radium proved the key to unlocking the atom's structure. Radium's main practical use has been in medicine, producing radon gas from radium chloride to be used in radiotherapy for cancer. This was a process started in Marie Curie's time. The early researchers found they received skin burns from handling the radioactive materials, and when the Curies worked with doctors, they discovered that radiation could be used to reduce or even cure tumours. This became known as Curie therapy, and the Sorbonne in Paris set up a laboratory partly for Curie to continue her research, and partly to study the medical applications of radiation, which would become known as the Radium Institute. If you were to hold a piece of radium in your hand, it would feel warm. Initially a bright white, it would blacken as it reacted with the air to form radium nitride. It would stay solid - radium doesn't melt until around 700 degrees Celsius. It would also crackle and spit on the surface of your palm as it reacted with the water on your skin to produce radium hydroxide. Holding radium not something I'd recommend, though. Radium is constantly decaying, producing the alpha particles Rutherford used, beta particles, which are fast electrons, and gamma rays, like high energy X-rays, which would be slamming through your flesh, disrupting the DNA and causing cellular damage. The isotopes of radium vary in half life - the time it takes for half the molecules in a sample to delay - from 1,602 years for the most stable isotope, radium 226, to 11½ days for radium 223. This is an element to be handled with care. Yet for anyone brought up on children's fiction full of ray guns and in a world were there were still X-ray machines to check your shoe size, it has a nostalgic feel that will ever make it fascinating. Chris Smith One wonders whether the podcasters of next century will be talking the same way about mobile phones, microwave ovens and MRI scanners. That was Bristol based science writer Brian Clegg with the story of radium. Next week to a metal capable of terrible cruelty to cancer. Katherine Haxton In the early 1960s, Barnett Rosenberg was conducting experiments on bacteria, measuring the effects of electrical currents on cell growth. The E.coli bacteria were abnormally long during the experiment, something that could not be attributed to the electric current. A number of platinum compounds were being formed due to reaction of the buffer and the platinum electrode. Cisplatin was found to inhibit cell division thus causing the elongation of the bacteria and was tested in was tested in mice for anticancer properties. Cisplatin today is widely used to treat epithelial malignancies with outstanding results in the treatment of testicular cancers. Chris Smith So we've got overgrown E.coli to blame for the discovery of platinum based anti cancer compounds. And you can find out how all of that came about with Keele University's Katherine Haxton on next week's Chemistry in its element. I'm Chris Smith, thank you for listening and for this week goodbye. (Promo) Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists.com. There's more information and other episodes of Chemistry in its element on our website at chemistryworld.org/elements. (End promo)
|
Video
Video
Resources
Resources
Terms & Conditions
Images © Murray Robertson 1999-2011
Text © The Royal Society of Chemistry 1999-2011
Welcome to "A Visual Interpretation of The Table of Elements", the most striking version of the periodic table on the web. This Site has been carefully prepared for your visit, and we ask you to honour and agree to the following terms and conditions when using this Site.
Copyright of and ownership in the Images reside with Murray Robertson. The RSC has been granted the sole and exclusive right and licence to produce, publish and further license the Images.
The RSC maintains this Site for your information, education, communication, and personal entertainment. You may browse, download or print out one copy of the material displayed on the Site for your personal, non-commercial, non-public use, but you must retain all copyright and other proprietary notices contained on the materials. You may not further copy, alter, distribute or otherwise use any of the materials from this Site without the advance, written consent of the RSC. The images may not be posted on any website, shared in any disc library, image storage mechanism, network system or similar arrangement. Pornographic, defamatory, libellous, scandalous, fraudulent, immoral, infringing or otherwise unlawful use of the Images is, of course, prohibited.
If you wish to use the Images in a manner not permitted by these terms and conditions please contact the Publishing Services Department by email. If you are in any doubt, please ask.
Commercial use of the Images will be charged at a rate based on the particular use, prices on application. In such cases we would ask you to sign a Visual Elements licence agreement, tailored to the specific use you propose.
The RSC makes no representations whatsoever about the suitability of the information contained in the documents and related graphics published on this Site for any purpose. All such documents and related graphics are provided "as is" without any representation or endorsement made and warranty of any kind, whether expressed or implied, including but not limited to the implied warranties of fitness for a particular purpose, non-infringement, compatibility, security and accuracy.
In no event shall the RSC be liable for any damages including, without limitation, indirect or consequential damages, or any damages whatsoever arising from use or loss of use, data or profits, whether in action of contract, negligence or other tortious action, arising out of or in connection with the use of the material available from this Site. Nor shall the RSC be in any event liable for any damage to your computer equipment or software which may occur on account of your access to or use of the Site, or your downloading of materials, data, text, software, or images from the Site, whether caused by a virus, bug or otherwise.
We hope that you enjoy your visit to this Site. We welcome your feedback.
© Murray Robertson 1998-2017.
Data
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.
Podcasts
Produced by The Naked Scientists.
Periodic Table of Videos
Created by video journalist Brady Haran working with chemists at The University of Nottingham.
