Search results
Strontium. Granules of strontium in a glass tube. A piece of strontianite. Strontium is a chemical element. It has the chemical symbol Sr. It has the atomic number 38. It is a metal. The color of the metal is silver-white or yellow-silver. The metal is soft, and highly reactive chemically.
Strontium is a chemical element; it has symbol Sr and atomic number 38. An alkaline earth metal, strontium is a soft silver-white yellowish metallic element that is highly chemically reactive. The metal forms a dark oxide layer when it is exposed to air.
- Overview
- Occurrence, properties, and uses
- Compounds
strontium (Sr), chemical element, one of the alkaline-earth metals of Group 2 (IIa) of the periodic table. It is used as an ingredient in red signal flares and phosphors and is the principal health hazard in radioactive fallout.
Strontium is a soft metal like lead and, when freshly cut, has a silvery lustre. It rapidly reacts in air to take on a yellowish colour; therefore, it must be protected from oxygen for storage. It does not occur free in nature. Although it is widely distributed with calcium, there are only two principal ores of strontium alone, celestine (SrSO4) and strontianite (SrCO3).
Britannica Quiz
118 Names and Symbols of the Periodic Table Quiz
A mineral from a lead mine near the village of Strontian, in Argyll, Scotland, was originally misidentified as a type of barium carbonate, but Adair Crawford and William Cruickshank in 1789 noted that it was likely a different substance. The chemist Thomas Charles Hope named the new mineral strontites, after the village, and the corresponding “earth” (strontium oxide, SrO) was accordingly referred to as strontia. The metal was isolated (1808) by Sir Humphry Davy, who electrolyzed a mixture of the moist hydroxide or chloride with mercuric oxide, using a mercury cathode, and then evaporated the mercury from the resultant amalgam. He used the stem of the word strontia to form the name of the element.
Its cosmic abundance is estimated as 18.9 atoms (on a scale where the abundance of silicon = 106 atoms). It composes about 0.04 percent of Earth’s crust. The most important commercial source of strontium is celestine; more than two-thirds of the world’s supply comes from China, with Spain and Mexico supplying much of the remainder. Strontium may be obtained in the form of sticks by the contact cathode method of electrolysis, in which a cooled iron rod, acting as a cathode, just touches the surface of a fused mixture of potassium and strontium chlorides and is raised as the strontium solidifies on it. Metallic strontium may be also obtained by reduction of the oxide with aluminum. The metal is malleable and ductile and a good conductor of electricity, but there are relatively few uses for elemental strontium. One of them is as an alloying agent for aluminum or magnesium in cast engine blocks and wheels; the strontium improves the machinability and creep resistance of the metal.
Naturally occurring strontium is a mixture of four stable isotopes: strontium-88 (82.6 percent), strontium-86 (9.9 percent), strontium-87 (7.0 percent), and strontium-84 (0.56 percent). Depending on the location, it is possible for the ratios of strontium-87 to strontium-86 to differ by more than a factor of 5. This variation is used in dating geological samples and in identifying the provenance of skeletons and clay artifacts. About 16 synthetic radioactive isotopes have been produced by nuclear reactions, of which the longest-lived is strontium-90 (28.9-year half-life). This isotope, formed by nuclear explosions, is considered the most dangerous constituent of fallout. Because of its chemical resemblance to calcium, it is assimilated in bones and teeth, where it continues ejecting electrons that cause radiation injury by damaging bone marrow, impairing the process of forming new blood cells, and possibly inducing cancer. Under controlled conditions, however, it has been used for treatment of some superficial cancers and bone cancer. It is also used as a source in thickness gauges and has been used in radioisotope thermoelectric generators, where the heat of its radioactive decay is converted to electricity for long-lived, lightweight power sources in navigation buoys, remote weather stations, and space vehicles. Strontium-89 is employed in the treatment of bone cancer, as it targets bone tissues, delivers its beta radiation, and then decays in a few months’ time (half-life 51 days).
In general, the chemistry of strontium is quite similar to that of calcium. In its compounds strontium has an exclusive oxidation state of +2, as the Sr2+ ion. The metal is an active reducing agent and readily reacts with halogens, oxygen, and sulfur to yield halides, oxide, and sulfide.
Strontium compounds have rather limited commercial value because the corresponding calcium and barium compounds generally serve the same purpose yet are cheaper. A few, however, have found application in industry and elsewhere. There is currently no substitute for the brilliant crimson colour produced by strontium salts such as strontium nitrate, Sr(NO3)2, and strontium chlorate, Sr(ClO3)2, in fireworks, flares, and tracer ammunition. About 5–10 percent of all strontium production is consumed in pyrotechnics. Strontium hydroxide, Sr(OH)2, is sometimes used to extract sugar from molasses because it forms a soluble saccharide from which the sugar can be easily regenerated by the action of carbon dioxide. Strontium monosulfide, SrS, is employed as a depilatory and as an ingredient in phosphors for electroluminescent devices and luminous paints.
People also ask
What does strontium mean?
Is strontium a radioactive element?
Is strontium an alkaline earth metal?
Why is strontium a soft metal?
May 29, 2018 · strontium (symbol Sr) Silvery-white, metallic element of the alkaline-earth metals in Group II of the periodic table. Resembling calcium physically and chemically, it occurs naturally in strontianite and celestite and is extracted by electrolysis.
The Editors of Encyclopaedia Britannica. Below is the article summary. For the full article, see strontium . strontium , Chemical element, one of the alkaline earth metal s, chemical symbol Sr, atomic number 38. A soft metal, it has a silvery lustre when freshly cut but reacts rapidly with air.
Apr 14, 2024 · Strontium is a chemical element with the symbol Sr and atomic number 38. It is an alkaline earth metal that is soft and silver-white when freshly cut, but tarnishes to a yellowish color in air. Strontium is chemically similar to its group neighbors, calcium and barium.
