Radium is an alkaline earth metal and was discovered in 1898 by Marie and Pierre Curie. It is a lustrous metal and is widely used in various industry.
Discovery and history
Radium was discovered in 1898 by Marie and Pierre Curie (a Polish and French chemist, respectively) . They isolated pure radium in 1911, via electrolysis of radium chloride. Today, radium can be obtained as a byproduct of refining uranium and is usually sold as radium chloride (RaCl2) or radium bromide (RaBr2) and not as a pure material.
|Periodic Table Classification||Group 2
|State at 20C||Solid|
|Color||Silvery white metallic|
|Electron Configuration||[Rn] 7s2|
|Electron Shell||2, 8, 18, 32, 18, 8, 2|
|Density||5.5 g.cm-3 at 20°C|
|Atomic Mass||226 g.mol -1|
|Electronegativity according to Pauling||0.9|
In nature, radium is found in uranium and thorium ores in trace amounts as small as a seventh of a gram per ton of uraninite. Due to the high solubility of its compounds in water, radium is extracted by successive lixiviation of the referred ores.  Radium has an abundance in the Earth’s crust by weight about 1 part per trillion. This makes it the 84thmost abundant element. Radium originally found in pitchblende ore. It was derived from Latin word radius which means rays.
Radium is a radioactive element of the alkaline earth series of metals. Radium is silvery, lustrous, soft and radioactive element. Its atomic symbol Ra, atomic number 88, atomic weight 226, solid at room temperature. Melting point 700 C and boiling point 1140 C. It is 6th element in group 2 of periodic table. Radium has density 5.5g/cm3 higher than barium.
Radium readily oxidizes on exposure to air, and is turned from almost pure white to black. Radium is luminescent, corrodes in water to form radium hydroxide. Although is the heaviest member of the alkaline-earth group it is the most volatile.  It forms the colorless Ra2+ cation in aqueous solution, which is highly basic and does not form complexes readily. Its compounds display a faint bluish glow in the dark, due to its radioactivity and the electrons release their energy as light when they are de-excited. It is interacted by water with vigorous evolution of hydrogen and by air with the formation of the nitride. It occurs exclusively as the Ra2+ ion in all its compounds. The sulfate, RaSO4, is the most insoluble sulfate known, and the hydroxide, Ra (OH)2, is the most soluble of the alkaline-earth hydroxides. Radium and its salts show luminescence and impart a carmine color to flame. Being radioactive it emits alpha and beta particles as well as gamma rays when mixed with beryllium it produces neutron. Most radium compounds are simple ionic compound.
- Radium is used in luminous paint.
- Used in medicine to produce radon gas.
- Radium and beryllium were once used as a portable source of neutrons.
- Radium isotopes are used for cancer treatment
- Radium is used as additive in products like toothpaste, hair creams and even food items.
- As additive in products like toothpaste, hair creams,
- It is used in various physics experiments.
Salt of Radium
- Radium hydroxide: Readily soluble among alkaline hydroxide
- Radium chloride: Colorless luminous compound, it becomes yellow after some time due to self-damage by the alpha radiation.
- Radium bromide: Colorless luminous compound that is soluble in water.
- Radium nitrate: White compound that can be made by dissolving radium carbonate in nitric oxide. Radium forms many insoluble salts, including sulfate, chromate, carbonate, iodate, and nitrate.
Like radioactive elements radium is a dangerous substance to handle. It gives off radiation which can kill living cells. This property is desirable in treating cancer. Killing cancer cells can help a patient recover from the disease. But great care must be taken in using radium for this purpose. Its radiation can also kill healthy cells.  Radium levels in drinking water may be high when it is extracted from deep wells that are located near radioactive waste disposal sites. Exposure to higher levels of radium may result in health effects, such as teeth fracture, anemia and cataract. 
Around 33 isotopes have been discovered with mass number ranging from Ra 202 to 234. But there are four naturally occurring isotopes, including Radium -223, Radium -224, Radium- 226, Radium- 228. The most stable isotope is radium-226, with a half-life of about 1600 years. It decays into radon-222 through alpha decay or into lead-212 by ejecting a carbon-14 nucleus.