Periodic Table > Radium
 

Terminology


Allotropes
Some elements exist in several different structural forms, these are called allotropes.


For more information on Murray Robertson’s image see Uses and properties facts below.

 

Fact box terminology


Group
Elements appear in columns or ‘groups’ in the periodic table. Members of a group typically have similar properties and electron configurations in their outer shell.


Period
Elements are laid out into rows or ‘periods’ so that similar chemical behaviour is observed in columns.


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, principal, diffuse, and fundamental.


Atomic Number
The number of protons in the nucleus.


Atomic Radius/non -bonded (Å)
based on Van der Waals forces (where several isotopes exist, a value is presented for the most prevalent isotope). These values were calculated using a multitude of methods including crystallographic data, gas kinetic collision cross sections, critical densities, liquid state properties, for more details please refer to the CRC Handbook of Chemistry and Physics.


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


Isotopes
Elements are defined by the number of protons in its centre (nucleus), whilst the number of neutrons present can vary. The variations in the number of neutrons will create elements of different mass which are known as isotopes.


Melting Point (oC)
The temperature at which the solid-liquid phase change occurs.


Melting Point (K)
The temperature at which the solid-liquid phase change occurs.


Melting Point (oF)
The temperature at which the solid-liquid phase change occurs.


Boiling Point (oC)
The temperature at which the liquid-gas phase change occurs.


Boiling Point (K)
The temperature at which the liquid-gas phase change occurs.


Boiling Point (oF)
The temperature at which the liquid-gas phase change occurs.


Sublimation
Elements that do not possess a liquid phase at atmospheric pressure (1 atm) are described as going through a sublimation process.


Density (kgm-3)
Density is the weight of a substance that would fill 1 m3 (at 298 K unless otherwise stated).


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.


Key Isotopes (% abundance)
An element must by definition have a fixed number of protons in its nucleus, and as such has a fixed atomic number, however variants of an element can exist with differing numbers of neutrons, and hence a different atomic masses (e.g. 12C has 6 protons and 6 neutrons and 13C has 6 protons and 7 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 (where several isotopes exist, a value is presented for the most prevalent isotope).

Fact box

 
Group Melting point 696 oC, 1284.8 oF, 969.15 K 
Period Boiling point Unknown 
Block Density (kg m-3) 5000 
Atomic number 88  Relative atomic mass 226.025  
State at room temperature Solid  Key isotopes 226Ra 
Electron configuration [Rn] 7s2  CAS number 7440-14-4 
ChemSpider ID 4886483 ChemSpider is a free chemical structure database
 

Uses and properties terminology


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.


Natural Abundance

Where this element is most commonly found in nature.


Biological Roles

The elements role within the body of humans, animals and plants. Also functionality in medical advancements both today and years ago.


Appearance

The description of the element in its natural form.

Uses and properties

 
Image explanation
Dangerous luminosity. Imagery reflecting the former use of the element in luminous paint used for clock and watch dials.
Appearance
A radioactive metal found naturally in uranium ores. It was extracted from this source for many years for cancer treatment and for the luminous paint applied to clock and watch dials. Production is now as little as 100 grammes per year.
Uses
Radium was formerly used in the production of luminous paints, but this is now considered too hazardous. The element gives off small amounts of radon gas which has been used to treat cancer, but this use is now also considered too toxic - other radioactive sources are more powerful and safer to use.
Biological role
Radium has no known biological role. It is toxic due to its radioactivity.
Natural abundance
Radium is present in all uranium ores, and could be extracted as a by-product of uranium refining. The usual source of pitchblende comes from Bohemia, but some radium-containing ores are found in Canada and the USA. Annual production of this element is less than 100 grams.
 
Atomic data terminology

Atomic radius/non -bonded (Å)
Based on Van der Waals forces (where several isotopes exist, a value is presented for the most prevalent isotope). These values were calculated using a multitude of methods including crystallographic data, gas kinetic collision cross sections, critical densities, liquid state properties,for more details please refer to the CRC Handbook of Chemistry and Physics.


Electron affinity (kJ mol-1)
The energy released when an additional electron is attached to the neutral atom and a negative ion is formed (where several isotopes exist, a value is presented for the most prevalent isotope). *


Electronegativity (Pauling scale)
The degree to which an atom attracts electrons towards itself, expressed on a relative scale as a function bond dissociation energies, Ed in eV. χA - χB =(eV)-1/2sqrt(Ed(AB)-[Ed(AA)+Ed(BB)]/2), with χH set as 2.2 (where several isotopes exist, a value is presented for the most prevalent isotope).


1st Ionisation energy (kJ mol-1)
The minimum energy required to remove an electron from a neutral atom in its ground state (where several isotopes exist, a value is presented for the most prevalent isotope).


Covalent radius (Å)
The size of the atom within a covalent bond, given for typical oxidation number and coordination (where several isotopes exist, a value is presented for the most prevalent isotope). ***

Atomic data

 
Atomic radius, non-bonded (Å) 2.830 Covalent radius (Å) 2.11
Electron affinity (kJ mol-1) 9.649 Electronegativity
(Pauling scale)
0.900
Ionisation energies
(kJ mol-1)
 
1st
509.288
2nd
979.050
3rd
-
4th
-
5th
-
6th
-
7th
-
8th
-
 

Mining/Sourcing Information

Data for this section of the data page has been provided by the British Geological Survey. To review the full report please click here or please look at their website here.


Key for numbers generated


Governance indicators

1 (low) = 0 to 2

2 (medium-low) = 3 to 4

3 (medium) = 5 to 6

4 (medium-high) = 7 to 8

5 (high) = 9


Reserve base distribution

1 (low) = 0 to 30 %

2 (medium-low) = 30 to 45 %

3 (medium) = 45 to 60 %

4 (medium-high) = 60 to 75 %

5 (high) = 75 %

(Where data are unavailable an arbitrary score of 2 was allocated. For example, Be, As, Na, S, In, Cl, Ca and Ge are allocated a score of 2 since reserve base information is unavailable. Reserve base data are also unavailable for coal; however, reserve data for 2008 are available from the Energy Information Administration (EIA).)


Production Concentration

1 (low) = 0 to 30 %

2 (medium-low) = 30 to 45 %

3 (medium) = 45 to 60 %

4 (medium-high) = 60 to 75 %

5 (high) = 75 %


Crustal Abundance

1 (low) = 100 to 1000 ppm

2 (medium-low) =10 to 100 ppm

3 (medium) = 1 to 10 ppm

4 (medium-high) = 0.1 to 1 ppm

5 (high) = 0.1 ppm

(Where data are unavailable an arbitrary score of 2 was allocated. For example, He is allocated a score of 2 since crustal abundance data is unavailable.)


Explanations for terminology


Crustal Abundance (ppm)

The abundance of an element in the Earth's crust in parts-per-million (ppm) i.e. The number of atoms of this element per 1 million atoms of crust.


Sourced

The country with the largest reserve base.


Reserve Base Distribution

This is a measure of the spread of future supplies, recording the percentage of a known resource likely to be available in the intermediate future (reserve base) located in the top three countries.


Production Concentrations

This reports the percentage of an element produced in the top three countries. The higher the value, the larger risk there is to supply.


Total Governance Factor

The World Bank produces a global percentile rank of political stability. The scoring system is given below, and the values for all three production countries were summed.


Relative Supply Risk Index

The Crustal Abundance, Reserve Base Distribution, Production Concentration and Governance Factor scores are summed and then divided by 2, to provide an overall Relative Supply Risk Index.

Supply risk

 
Scarcity factor Unknown
Country with largest reserve base Unknown
Crustal abundance (ppm) Unknown
Leading producer Unknown
Reserve base distribution (%) Unknown
Production concentration (%) Unknown
Total governance factor(production) Unknown
Top 3 countries (mined)
  • Unknown
Top 3 countries (production)
  • Unknown
 

Oxidation states and isotopes


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

Terminology


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. Free atoms have an oxidation state of 0, and the sum of oxidation numbers within a substance must equal the overall charge.


Important Oxidation states
The most common oxidation states of an element in its compounds.


Isotopes
Elements are defined by the number of protons in its centre (nucleus), whilst the number of neutrons present can vary. The variations in the number of neutrons will create elements of different mass which are known as isotopes.

Oxidation states and isotopes

 
Common oxidation states 2
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  223Ra 223.019 - 11.43 d  α 
  224Ra 224.02 - 3.66 d  α 
  226Ra 226.025 - 1599 y  α 
        > 4 x 1018 sf 
  228Ra 228.031 - 5.76 y  β- 
        βf 
 

Pressure and temperature - advanced terminology


Molar Heat Capacity (J mol-1 K-1)

Molar heat capacity is the energy required to heat a mole of a substance by 1 K.


Young's modulus (GPa)

Young's modulus is a measure of the stiffness of a substance, that is, 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 (GPa)

The shear modulus of a material is a measure of how difficult it is to deform a material, and is given by the ratio of the shear stress to the shear strain.


Bulk modulus (GPa)

The bulk modulus is a measure of how difficult to compress a substance. Given by the ratio of the pressure on a body to the fractional decrease in volume.


Vapour Pressure (Pa)

Vapour pressure is the 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

 
Molar heat capacity
(J mol-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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History

Radium was discovered in 1898 by Marie Curie and Pierre Curie. They managed to extract 1 mg of radium from ten tonnes of the uranium ore pitchblende (uranium oxide, U3O8), a considerable feat, given the chemically methods of separation available to them. They identified that it was a new element because its atomic spectrum revealed new lines. Their samples glowed with a faint blue light in the dark, caused by the intense radioactivity exciting the surrounding air.


The metal itself was isolated by Marie Curie and André Debierne in 1911, by means of the electrolysis of radium chloride. At Debierne’s suggestion, they used a mercury cathode in which the liberated radium dissolved. This was then heated to distil off the mercury leaving the radium behind.

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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 gramme 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 dot com. There's more information and other episodes of Chemistry in its element on our website at chemistryworld dot org forward slash elements. 

(End promo)

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Resources

Description :
In this experiment you will be observing and interpreting the changes when drops of solutions of various anions are added to drops of solutions of Group 2 element cations.
Description :
In this experiment the pH of various oxides is tested.
Description :
Assessment for Learning is an effective way of actively involving students in their learning.  Each session plan comes with suggestions about how to organise activities and worksheets that may be use...
Description :
Metals in Group 2 of the Periodic Table are less reactive than those in Group 1. This experiment indicates the relative reactivity of elements within the group.
Description :
In this experiment you will be looking to see whether precipitates form when you add drops of solutions of sulphates or carbonates to drops of solutions of Group 1 or 2 metal ions.
Description :
Many elements react with oxygen on heating. These reactions and the properties of their products illustrate the periodic nature of the elements.
 

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References

 
Images:  Visual Elements © Murray Robertson 2011
Mining and Sourcing data:  British Geological Survey – natural environment research council.
Text:  John Emsley Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, 2nd Edition, 2011.
Additional information for platinum, gold, neodymium and dysprosium obtained from Material Value Consultancy Ltd www.matvalue.com
Data: CRC Handbook of Chemistry and Physics, CRC Press, 92nd Edition, 2011.
G. W. C. Kaye and T. H. Laby Tables of Physical and Chemical Constants, Longman, 16th Edition, 1995.
Members of the RSC can access these books through our library.