Barium
Symbol: Ba
Atomic Number: 56
Atomic Mass: 137.327 amu (atomic mass units)
Melting Point: 725.0 C (998.15 K, 1337.0 F)
Boiling Point: 1140.0 C (1413.15 K, 2084.0 F)
Number of Protons: 56
Number of Electrons: 56
Number of Neutrons: 81
Classification: Alkaline Earth
Crystal Structure: Cubic
Density @ 293 K: 3.51 grams per centimeter
Color: Silvery-white
Barium was discovered by the English chemist Sir Humphry Davy in 1808. To do this he used electrolysis on a molten sample of barium oxide known as baryta. The name barium comes from the Greek word “barys” which means heavy.
Barium is never found as a pure element in nature as it reacts with oxygen to form barium oxide and water to form barium hydroxide. It also reacts with alcohol.
Barium has six stable isotopes along with one unstable isotope which occur naturally. The most common stable isotope is barium-138 which makes up 71.698% of the total abundance. Unstable barium-130 makes up only 0.106% of the total and has a half life of 350 trillion years. Over thirty man-made unstable isotopes of barium have been produced.
In the 1500’s some stones found near Bologna in Italy were seen to glow in the dark for up to six years if they were subjected to intense heat in a charcoal oven. These stones, called Bologna stones, contained an impure source of barium sulfate. The alchemists of the time thought this chemical reaction was an indication that the stones had some form of magical power
The element is found in the mineral ores barite and witherite. It is usually produced industrially by the electrolysis of barium chloride.
Barium is used as a getter. This is an agent that removes residual gases from vacuum tubes.
Most industrial uses of barium involve one of its many compounds.
* Barium sulfate is used to form two white pigments. Combined with sodium sulfate the pigment is blanc fixe while the pigment lithophone combines with barium sulfate with zinc oxide. Another use for barium sulfate is as a filler with plastics, rubber and resins. This compound is also the one used in a barium meal, the medical procedure for imaging the intestinal tract as it is opaque to X-rays and insoluble in water.
* Barium carbonate forms part of the clay slurries used in drilling for oil. It is also used in the manufacture of ceramics and glass.
* Barium nitrate will burn with an intense green flame. This property is employed in the manufacture of fireworks and signal flares.
* Barium oxide is employed as a desiccant as it easily absorbs water.
* Barium peroxide is a bleaching agent that activates when wet as it produces hydrogen peroxide when mixed with water.
* Barium chloride is sometimes used as a water softener.
* Barium titanate is a dielectric compound used in the manufacture of capacitors.
* Barium ferrite is used to make magnets.
