Strontium
Element Name: Strontium
Atomic Number: 38
Atomic Mass: 87.62
Atomic Symbol: Sr
Melting Point: 777° C
Boiling Point: 1382° C
Strontium is a grayish to dull silver metal which rapidly oxides and turns yellow when exposed to air. As an alkaline earth element strontium is highly reactive such that finely powdered strontium will ignite spontaneously in air. It is almost exclusively divalent, and its chemical properties are similar to the other alkaline earth elements calcium and barium. The named comes from the Scottish village “Strontian” from which the original samples of strontianite (also named for the same village) were collected. Strontium has four stable isotopes that occur in nature, and one of these, Strontium-87, is radiogenic (meaning it’s made from a heavier radioactive element decomposing). It has 16 unstable isotopes too, but the most important of these is Strontium-90, a primary component in nuclear fallout.
Interesting Facts:
Historically, strontium was used in the processing of sugar beets. As much as 150,000 tons of strontium hydroxide were used in this process per year. Because strontium is so similar to calcium it is often found in bones. Strontium renelate is a prescription drug found in the EU which has been demonstrated to increase bone density by more than 12%. However, the infamous Strontium-90 can also be introduced to bone, causing several bone diseases and disorders including cancer. Strontium aluminate paints can glow in the dark by absorbing ambient light and then slowly releasing it. The isotopes of strontium are not all evenly distributed across the earth’s surface. By associating certain ratios of strontium isotopes to geographic locations it’s possible to determine where a bone sample came from. This is useful in determining the place of origin of migratory species and commingled human remains.
Sources:
Strontium is too reactive to be found in its elemental form in nature. Strontium is primarily found in the minerals celestine, strontianite, and putnisite. About 300,000 tons of celestine (the most abundant strontium-containing mineral) are processed every year. China is the largest producer of strontium, as it makes up more than two-thirds of the world’s supply. Other major producers include Spain, Mexico, Argentina, Iran, and Turkey. It is the 15th most common element in the earth’s crust, making up 370 parts per million.
Industrial Uses:
Cathode Ray Tubes make up 75% of the production of strontium. The glass in a CRT is specially prepared to absorb any X-rays that are emitted by the device, so a combination of lead, strontium oxide, and barium oxide is used to block them. Strontium carbonate and a few other strontium salts are used in fireworks to make a deep red color. Strontium-90 is also used as a power source in radioisotope thermoelectric generators (RTGs). The Soviet Union used almost 1000 90Sr RTGs to power lighthouses and weather stations. Certain cancer therapies also use Strontium-90 because its long half-life and beta emissions are good for radiotherapy. Strontium is also a good additive. Aluminum-silicon casting alloys are very brittle, and adding a small amount of strontium makes it stronger. Strontium oxide is used in pottery and ceramics to improve glazes.
References:
“Facts About Strontium.” Livescience. Livescience.com, 20 May 2013. Web. 26 July
2016.
“Strontium.” Wikipedia. Wikimedia Foundation, n.d. Web. 26 July 2016.
“Strontium Element Facts / Chemistry.” Chemicool. Chemicool.com, 24 July 2012.
Web. 26 July 2016.
Gray, Theodore W., and Nick Mann. The Elements: A Visual Exploration of Every
Known Atom in the Universe. New York: Black Dog & Leventhal, 2009. Print.