Two scientists named Robert Bunsen and Gustav Kirchhoff discovered the element rubidium in 1861. The technique that they used to discover the element was called spectroscopy, which they had invented two year previously to the discovery of rubidium. In 1861, Bunsen and Kirchhoff began studying the mineral lepidolite, which had been discovered in Saxony, Germany. As the studied the mineral, they did many different tests. One test they did was that they put hydrochloroplatanic acid onto the lepidolite mineral to precipitate potassium chloroplatinate from it. Another salt was found in the potassium chloroplatinate when this was finished. Bunsen and Kirchhoff placed the unidentified salt into the Bunsen burner and saw that its spectrum had contained many new lines, two of which were most outstanding to them. When they took notes on this new discovery, they wrote that the line spectrum of the salt was not previously known by any other body. They also noted that two of the lines were particularly remarkable because the lines were lying beyond Fraunhofer’s line in the outermost portion of the red solar spectrum. Bunsen and Kirchhoff dubbed this metal as the element rubidium from the Latin word rubidius, which was used to express the darkest red color.
Rubidium is a non-toxic metal that is soft, silvery-white element. It is the fourth alkali metal in the alkali metal family. When rubidium is burnt, it gives off a reddish violet color in its flame. Rubidium is solid at room temperature, but it easily melts at 39.3 degrees Celsius. Rubidium can create alloys with other elements such as gold, caesium, sodium, and potassium. Even though rubidium is non-toxic, it is unsafe in some instances. Rubidium reacts violently with air and water causing it to explode. It explodes in the water because during the reaction corrosive rubidium hydroxide and hydrogen gas is created. Then hydrogen gas in this chemical reaction is then ignited because of the heat of the reaction causing the explosion.
Rubidium is not found in nature in its pure state, it is found in compounds with other elements. The main ore that contains rubidium, which was stated earlier, is lepidolite. The lepidolite ore contains about one 1.5% rubidium. Rubidium is usually obtained as a byproduct of lithium production. Rubidium metal can also be made by reducing rubidium chloride with calcium. If you want to buy pure rubidium, the cost per one hundred grams is $1200.
Rubidium has many uses. Rubidium is used as a component in photocells, which are devices that capture light and turn the light in electrical energy. It is used in vacuum tubes as a “getter”, which is used to remove trace gasses in the tubes. It is also used as working fluid in vapor turbines. Rubidium compounds are used to give fireworks a purple color. Some rubidium salts are used in making special glassware and some ceramics. One of rubidium’s isotopes, rubidium 87, is slightly radioactive and used extensively in dating rocks. The isotope rubidium 82 is used in some types of medical screenings.
So rubidium has many uses and properties that we know of, but none of them would have been known if it was not for Robert Bunsen and Gustav Kirchoff.
Gustav Kirchhoff
