An element that forms heavy minerals
Metallic barium is a soft, ductile alkaline earth metal of a silvery-white color. Its name comes from the Ancient Greek word meaning “heavy”, because of the high density of its compounds.
How barium was discovered
In the form of an oxide, barium was discovered by Carl Scheele and Johan Gahn in 1774. In 1808, barium was first extracted in pure form by Humphrey Davy, who conducted the electrolysis of moist barium hydroxide with a mercury cathode. Davy heated the barium amalgam that was formed in this process, and after the mercury evaporated, he obtained pure metallic barium.
Distribution in nature
This element has high chemical activity and is not found in nature in pure form. It is mainly contained in the minerals barite (BaSO₄) and witherite (BaCO₃). One of the compounds of barium is its sulfide. BaS became known as “Bologna phosphorus” after the experiments by the Italian alchemist Vincenzo Casciarolo: he heated barite and discovered a substance that glowed in the dark. After the substance was illuminated by the sun all day, it continued to glow all night.
Application of barium and its compounds
In pure form, barium is used as a getter (gas absorber) in electronic devices with a high vacuum, and is added to liquid metal coolants.
Barium compounds are used in the manufacture of ceramic condensers, piezoelectric microphones and piezoceramic radiators (barium titanate), Barium compounds are also used in optics (monocrystals of barium fluoride), in atomic hydrogen energy for obtaining hydrogen and oxygen in the Oak Ridge cycle (barium chromate), in nuclear energy for coating uranium rods (barium oxide in a special sort of glass), and in various chemical sources of electrical energy. Barium peroxide, together with copper oxides and rare earth metals, is used to make superconductive ceramics, which can function at temperatures above 77.4 K. Barium nitrate and chlorate are used in fireworks to create a green flame.
All water-soluble barium compounds are toxic and cause serious problems with the digestive tract, and paralysis of the muscles and heart. However, barium sulfate, which is insoluble in water, found application in medicine. “Barite porridge” (a suspension of barium sulfate) is given to patients for X-ray examinations of the digestive organs. Barium absorbs X-rays well. The manufacturers of Lego attempted to make use of this property, adding it to plastic for bricks. If a child accidentally swallowed a piece of Lego, it could easily be found in the digestive tract on an X-ray scan. Unfortunately, the plastic lost durability, and industrial barium sulfate was not sufficiently pure and was toxic, so the idea was dropped.