Radium

Radium() is a radiactive chemical element, and the heaviest of the Alkaline-earth metals of the periodic table. It is a silvery white metal and does not occur freely in nature.
==Discovery==
Radium was discovered by Marie Curie, a Polish chemist, and Pierre Curie, a French chemist, in 1898. They obtained raidum from pitchblende, a material that contains uranium, after noticing that unrefined pitchblende was more radioactive than the uranium that was separated from it. They speculated that pitchblende must contain another radioactive element. They refined severals tons of pitchblende in order to obtain tiny amounts of radium and polonium, another radioactive element discovered by Madam Curie.
==Curie==
Curie is a unit used to desribe the activity of a radioactive substance based on radium-226 isotope. It is equal to the number of atoms in one gram sample of radium-226 that will decay in one second, or 3.7 \times 10^{10}.
==Uses==
Radium was used to make self-luminous paints for watches, aircraft instrument dials and other instrumentation, but has now been replaced by cobalt-60, which is a less dangerous radioactive material.
A mixture of radium and beryllium will emit neutrons and is used as a neutron source.
Radium is used to produce radon, a radioactive gas used to treat some types of cancer. A single gram of radium-226 will produce 1.0 \times 10^{-4} ml of radon a day.
Category:Element