Discovery date : 1898
Discovered by: Pierre and Marie Curie
Origin of the name: The name is derived from the Latin 'radius', meaning ray.
Allotropes : -
~>RADIUM is a chemical element with symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (rather than oxygen) on exposure to air, forming a black surface layer of radium nitride (Ra3N2).
| FACT BOX | |||
| 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 | |
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.