![]() The isotope gives off radiation, some of which passes through the metal sheeting. The sheeting is carried along on a conveyor belt beneath a small container of strontium-90. Metal sheeting for construction must be the same thickness throughout. For example, it is used to monitor the thickness of materials. Today, strontium-90 has a number of useful applications. It is a toxic substance which, at one time, was the cause of great concern because of its connection to atomic bomb testing. One radioactive isotope of strontium, strontium-90, is of special interest. These particles stick in the atoms and make them radioactive. Radioactive isotopes are produced when very small particles are fired at atoms. A radioactive isotope is one that breaks apart and gives off some form of radiation. Each variation is an isotope.Ībout ten radioactive isotopes of strontium are known also. The number of protons determines the element, but the number of neutrons in the atom of any one element can vary. The mass number represents the number of protons plus neutrons in the nucleus of an atom of the element. ![]() The number written to the right of the element's name is the mass number. Isotopes differ from each other according to their mass number. Isotopes are two or more forms of an element. They are strontium-84, strontium-86, strontium-87, and strontium-88. Isotopesįour isotopes of strontium occur in nature. A small amount of strontium is also obtained from mines in California and Texas. Important world sources of strontium are Mexico, Spain, Turkey, and Iran. Celestine contains primarily strontium sulfate (SrSO 4), while strontianite contains mostly strontium carbonate (SrCO 3). The most common minerals containing strontium are celestine and strontianite. That makes it about as abundant as fluorine and its alkaline earth partner, barium. It ranks about 15th among the elements found in the Earth. Strontium is a relatively abundant element in the Earth's crust. Strontium also reacts with cold water and with acids to release hydrogen gas: The compounds formed are strontium hydride (SrH 2) and strontium nitride (Sr 3N 2). Strontium is active enough to combine even with hydrogen and nitrogen when heated. In a finely divided or powdered form, strontium catches fire spontaneously and bums vigorously. In this way, the metal does not come into contact with air. Strontium is so active it must be stored under kerosene or mineral oil. Its density is 2.6 grams per cubic centimeter. Strontium has a melting point of about 757 ☌ (1,395 ☏) and a boiling point of 1,366 ☌ (2,491 ☏). The film gives the metal a yellowish color. When exposed to air, it combines with oxygen to form a thin film of strontium oxide (SrO). Strontium is a silvery-white, shiny metal. The electric current broke the compound into its two elements: He passed an electric current through molten (melted) strontium chloride. In 1808, Davy found a way to produce pure strontium metal. ![]() Strontia was later found to be a compound of strontium and oxygen. He named it after a lead mine in Strontia, Scotland, from which the samples came. He concluded that the minerals contained a new element. They did not have the properties of barium minerals. Baryte is a mineral from which the element barium is obtained.īut Crawford found that some of the minerals did not behave as he expected. These minerals were thought to be a form of baryte. In 1790, he began studing certain minerals that were on display at St. Thomas's Hospital in London, England, and a professor of chemistry at Woolwich University. However, he was also interested in chemical research. One of its radioactive isotopes is used in industry and medical studies.Īdair Crawford was trained as a physician. It is also used in the manufacture of ceramics and specialty glass. (See sidebar on Davy in the calcium entry in Volume 1.)īy far the major use of strontium is in the production of color television tubes. However, the element was not prepared in pure form until nearly 20 years later by English chemist Humphry Davy (1778-1829). The existence of strontium was first recognized in 1790 by Irish physician Adair Crawford (1748-95). But it is less active than barium, below it in Group 2. Chemically, it is more active than calcium or magnesium, above it in the periodic table. Strontium occupies a middle position in the family. Other alkaline metals include beryllium, magnesium, calcium, barium, and radium. The periodic table is a chart that shows how chemical elements are related to one another. The alkaline earth metals make up Group 2 (IIA) of the periodic table. Strontium is a member of the alkaline earth metals. Note: This article, originally published in 1998, was updated in 2006 for the eBook edition.
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