Introducing Strontium: An Earthy and Reactive Metal
Strontium is a chemical element represented by the symbol Sr and possesses an atomic number of 38. It is classified as an alkaline earth metal, placing it in Group 2 of the periodic table, alongside elements such as calcium and magnesium. In its pure form, strontium is a soft, silvery-white metal that readily tarnishes to a yellowish color when exposed to air. Due to its high reactivity, it is never found freely in nature but always combined with other elements within various minerals.
Discovery and Naming
The journey to identify strontium began in the late 18th century. In 1790, Scottish physician and chemist Adair Crawford, while examining a mineral sample from a lead mine in Strontian, a village in Argyll, Scotland, observed properties distinct from other known minerals. He recognized it as a new substance, naming it strontianite. Later, in 1793, another Scottish chemist, William Cruickshank, further confirmed the presence of a new element within this mineral. The pure metallic element itself was eventually isolated by the English chemist Sir Humphry Davy in 1808 through the electrolysis of molten strontium chloride, solidifying its place on the periodic table and linking its name directly to its place of discovery in Scotland.
Properties and Applications of Strontium
Strontium is known for its energetic reactions. It reacts vigorously with water, producing hydrogen gas and strontium hydroxide. When ignited, strontium metal or its compounds burn with a vivid crimson (red) flame. This characteristic property makes it valuable in various applications globally.
One of the most recognizable uses of strontium compounds is in pyrotechnics, including fireworks and signal flares. The brilliant red color seen in celebrations worldwide is often attributed to the presence of strontium salts. Historically, strontium carbonate was a significant component in cathode ray tube (CRT) television screens and computer monitors, particularly those used in many households across North America, Europe, and Asia. Its role was to absorb X-rays generated by the high-voltage electron beams, protecting viewers from radiation exposure.
Furthermore, some compounds of strontium find applications in more specialized fields. Strontium aluminate, for instance, is a non-toxic pigment used in glow-in-the-dark paints and toys, often seen in children’s bedrooms. A radioactive isotope, strontium-90, is a product of nuclear fission and has been utilized as a power source in radioisotope thermoelectric generators (RTGs) for spacecraft and remote navigational beacons, providing continuous electrical power in environments where solar power is not feasible.
Five Quick Facts About Strontium
- Strontium is a highly reactive alkaline earth metal.
- It produces a distinctive brilliant red flame, making it ideal for fireworks.
- The element is named after the village of Strontian in Scotland.
- Strontium was historically crucial in older TV screens to block X-rays.
- One of its isotopes, Strontium-90, is a radioactive material used in some power generators for space missions.