Radium

Symbol: Ra Atomic number: 88 Atomic mass: 226.03 Radium is a white alkaline earth metal. It is highly radioactive, and somewhat unstable which causes it to glow faint blue. Radium melts at 700 __degrees__ celsius and it boils at 1737 __degrees__ celsius.



Radium is a chemical element with atomic number 88, represented by the symbol Ra. Radium is an almost pure-white alkaline earth metal, but it readily oxidizes on exposure to air, becoming black in __color__. All isotopes of radium are highly radioactive, with the most stable isotope being radium-226, which has a [|half-life] of 1601 years and decays into __radon gas__. Because of such instability, radium is luminescent, __glowing__ a faint blue.

Radium, in the form of radium chloride, was discovered by Marie Skłodowska-Curie and Pierre Curie in 1898. They extracted the radium compound from uraninite and published the discovery at the French Academy of Sciences five days later. Radium was isolated in its metallic state by Marie Curie and André-Louis Debierne through the __electrolysis__ of radium chloride in 1910. Since its discovery, it has given names like radium A and radium C 2 to several isotopes of other elements that are decay products of radium-226.

In __nature__, radium is found in uranium ores in trace amounts as small as a seventh of a gram per ton of uraninite. Radium is not necessary for living organisms, and adverse health effects are likely when it is incorporated into biochemical processes because of its radioactivity and chemical reactivity.

**Chemical Characteristics**

Radium is the heaviest known alkaline earth metal; its chemical properties mostly resemble those of barium. When exposed to air, radium reacts violently with it, forming radium nitride, which causes blackening of this white metal. It exhibits only the +2 oxidation state in solution. Radium ions do not form complexes easily, due to highly basic character of the ions. Most radium compounds coprecipitate with all barium, most strontium, and most lead compounds, and are ionic salts. The radium ion is colorless, making radium salts white when freshly prepared, turning yellow and ultimately dark with age owing to self-decomposition from the alpha radiation. Compounds of radium flame red-purple and give a characteristic spectrum. Like other alkaline earth metals, radium reacts violently with __water and oil__ to form radium hydroxide and is slightly more volatile than barium, which leads to lesser solubility of radium compounds compared to those of corresponding barium ones. Because of its geologically short half-life and intense radioactivity, radium compounds are quite rare, occurring almost exclusively in uranium ores.

Radium chloride, radium bromide, radium hydroxide and radium nitrate are soluble in water, with solubilities slightly lower than those of barium analogs for bromide and chloride, and higher for nitrate. Radium hydroxide is more soluble than hydroxides of other alkaline earth metals, actinium, and thorium, and more basic than barium hydroxide. It can be separated from these elements by their precipitation with ammonia. Out of insoluble radium compounds, radium sulfate, radium chromate, radium iodate, radium carbonate, and radium tetrafluoroberyllate are characterized. Radium oxide, however, remains uncharacterized, despite the fact that other alkaline-earth metals' oxides are common compounds for the corresponding metals.

Radioactive
 * Atomic Number:** 88
 * Atomic __Weight__:** 226
 * Melting Point:** 973 K (700°C or 1292°F)
 * Boiling Point:** 1413 K (1140°C or 2084°F)
 * Density:** 5 grams per cubic centimeter
 * Phase at Room Temperature:** Solid
 * Element Classification:** Metal
 * Period Number:** 7 **Group Number:** 2 **Group Name:** Alkaline Earth Metal


 * What's in a name?** From the Latin word for ray, **radius**.


 * Say what?** Radium is pronounced as **RAY-dee-em**.

Radium is over one million times as radioactive as the same mass of uranium. Its decay occurs in at least seven stages; the successive main products have been studied and were called radium emanation or exradio (now identified as radon), radium A (polonium), radium B (lead), radium C (bismuth), etc. Radon is a heavy gas, and the later products are solids. These products are themselves radioactive elements, each with an atomic weight a little lower than its predecessor. Radium loses about 1% of its activity in 25 years, being transformed into elements of lower atomic weight, with lead being the final product of disintegration. The SI unit of radioactivity is the becquerel (Bq), equal to one disintegration per second. The curie is a non-SI unit defined as that amount of radioactive material that has the same disintegration rate as 1 gram of radium-226 (3.7×1010 disintegrations per second, or 37 GBq). Radium metal maintains itself at a higher temperature than its surroundings because of the radiation it emits – alpha particles, beta particles , and gamma rays. More specifically, the alpha particles are produced by the radium decay, whereas the beta particles and gamma rays are produced by relatively short-half-life elements further down the decay chain.
 * Radioactivity**


 * History and Uses:**

Radium was discovered by Marie Sklodowska Curie, a Polish chemist, and Pierre Curie, a French chemist, in 1898. Marie Curie obtained radium from pitchblende, a material that contains uranium, after noticing that unrefined pitchblende was more radioactive than the uranium that was separated from it. She reasoned that pitchblende must contain at least one other radioactive element. Curie needed to refine several tons of pitchblende in order to obtain tiny amounts of radium and polonium, another radioactive element discovered by Curie. One ton of uranium ore contains only about 0.14 grams of radium. Today, radium can be obtained as a byproduct of refining uranium and is usually sold as radium chloride (RaCl 2 ) or radium bromide (RaBr 2 ) and not as a pure material.

Radium's most stable isotope, radium-226, has 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.

The Curie, a unit used to describe the activity of a radioactive substance, is based on radium-226. It is equal to the number of atoms in a one gram sample of radium-226 that will decay in one second, or 37,000,000,000 decays per second.

Radium had been used to make self-luminous paints for __watches__, aircraft instrument dials and other instrumentation, but has largely been replaced by cobalt-60, a less dangerous radioactive source. 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 0.000l milliliters of radon a day.

Radium is about one million times more active than uranium. The lab notebooks used by the Curies are too highly contaminated to be safely handled today.

Radium is highly radioactive and its decay product, radon gas, is also radioactive. Since radium is chemically similar to calcium, it has the potential to cause great harm by replacing calcium in bones. Exposure to radium can cause cancer and other disorders, because radium and its decay product radon emit alpha particles upon their decay, which kill and mutate cells. The dangers of radium were apparent from the start. The first case of so-called "radium-dermatitis" was reported in 1900, only 2 years after the element's discovery. The French physicist Antoine Becquerel carried a small ampoule of radium around in his waistcoat pocket for 6 hours and reported that his skin became ulcerated. Marie Curie also had a similar incident in which she experimented with a tiny sample that she kept in contact with her skin for 10 hours and noted how an ulcer appeared, although not for several days. Handling of radium has also been blamed for Curie's death due to aplastic anemia. Stored radium should be ventilated to prevent accumulation of radon. Emitted energy from the decay of radium also ionizes gases, affects photographic plates, and produces many other detrimental effects – to the extent that at the time of the Manhattan Project in 1944, the "tolerance dose" for workers was set at 0.1 microgram of ingested radium.
 * Hazards**


 * Estimated Crustal Abundance:** 9×10-7 milligrams per kilogram


 * Estimated Oceanic Abundance:** 8.9×10-11 milligrams per liter


 * Number of Stable Isotopes:** 0 (View all isotope data)


 * Ionization Energy:** 5.279 eV


 * Oxidation State:** +2