Radium Element Facts

General
States
Energies
Oxidation & Electrons
Appearance & Characteristics
Reactions & Compounds
Radius
Conductivity
Abundance & Isotopes

88 Ra 226.0254 Radium

World War II aircraft gauges containing radioactive radium. The radium glows and the gauges could be read in darkness. (Photo: EPA)

Name: Radium
Type: Alkali Earth Metal
Density @ 293 K: 5.5 g/cm³

Discovery of Radium Radium was discovered in 1898 by Marie S. Curie and her husband Pierre in pitchblende (mainly uranium dioxide UO₂). If pitchblende contains 50 percent uranium oxides, about eight tons of it is needed to extract 1 gram of radium.

Already that year the Curies had discovered polonium, a radioactive element whose properties they said were similar to bismuth's. Now, in radium - in the form of radium bromide - they had discovered a further radioactive element whose chemistry was very similar to that of group II metal barium.

Metallic radium was first isolated in 1910 by Marie S. Curie and Andre Debierne by the electrolysis of a solution of pure radium chloride.

The element's name comes from the Latin word 'radius', meaning ray, after the rays emitted by this radioactive element.

In the discovery of radioactivity, chemists realized that one of alchemy's dreams - the transmutation of elements - was possible.

Symbol: Ra
Atomic weight: 226.0254
Atomic volume: 45.20 cm³/mol

State (s, l, g): solid
Melting point: 973 K   (700 ^oC)

Boiling point: 1773 K   (1500 ^oC)

Specific heat capacity: 0.12 J g^-1 K^-1
Heat of fusion: 8.5 kJ mol^-1
1^st ionization energy: 509.4 kJ mol^-1
3^rd ionization energy: kJ mol^-1

Heat of atomization: 159 kJ mol^-1
Heat of vaporization : 113 kJ mol^-1
2^nd ionization energy: 979.1 kJ mol^-1
Electron affinity: kJ mol^-1

Shells: 2,8,18,32,18,8,2
Minimum oxidation number: 0
Min. common oxidation no.: 0
Electronegativity (Pauling Scale): 0.9

Electron configuration: [Rn] 7s²
Maximum oxidation number: 2
Max. common oxidation no.: 2
Polarizability volume: 38.3 ų

Structure: bcc: body-centered cubic
Hardness: mohs

Color: silvery white


Harmful effects:
Radium is highly radioactive and hence carcinogenic. Microscopic quantities of radium in the environment can lead to some accumulation of radium in bone tissue. Radium, like calcium, is a group II element and our bodies treat it in a similar way.

Characteristics:
Radium is a silvery-white metal. It is highly radioactive and its decay product, radon gas, is also radioactive. One result of radium's intense radioactivity is that the metal and its compounds glow in the dark. When it is exposed to air, it reacts with nitrogen to quickly form a black coating of radium nitride.

Radium's chemistry is similar to that of the other alkali earth metals. It reacts very vigorously with water to form hydrogen gas and radium hydroxide. It reacts with even more vigorously with hydrochloric acid to form radium chloride.

Uses:
Radium was used in the production of luminous paints, but this is now considered too dangerous. Radium chloride was used medicinally to produce radon gas for cancer treatment. Safer treatments are now available.

Reaction with air: vigorous, ⇒ RaO₂, Ra₃N₂
Reaction with 15 M HNO₃:
Oxide(s): RaO
Hydride(s):

Reaction with 6 M HCl:
Reaction with 6 M NaOH:
Chloride(s): RaCl₂

Atomic radius: 215 pm
Ionic radius (2+ ion): 162 pm
Ionic radius (2- ion): pm

Ionic radius (1+ ion): pm
Ionic radius (3+ ion): pm
Ionic radius (1- ion): pm

Thermal conductivity: 18.6 W m^-1 K^-1

Electrical conductivity: 1 x 10⁶ S m^-1