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Barium, Ba, 56, is a alkali-earth metal, and similar to the other alkali earth metals, it is very reactive, and will form toxic barium oxide quite quickly if left in air. It also will react quickly with water to form hydrogen and barium hydroxide, BaOH.

Barium hasn't found many uses in day-to-day life, probably the only use of it most people have seen are fireworks, which use barium nitrate for a green colored flame.

More unusual uses of barium include a use for x-ray scans, barium blocks x-rays strongly, so if a certain bodily feature must be observed, a solution of a barium compound is swallowed(or injected) to make it show up more clearly.

Barium was also used in old vacuum-tube amplifiers in order to acheive an extremely high vacuum inside a glass envelope. Because vacuum tubes needed a very high vacuum in order to work properly, it was necessary to find a way to remove even the smallest trace of gas from the glass envelope, so after pumping the air out as best they could, they would rely on a small plating of barium(and occasionally other very reactive metals) on the inside of the glass to react with, and thusly confine, any gasses left over in the tube.

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Barium Getter

Vacuum tubes such as these require that there be little to no gas of any kind inside the envelope, in order to allow thermionic emissions to flow through open space. Perhaps you didn't understand that, but it's important that vacuum tubes have VACUUM. You can pump most the air out, but it's nearly impossible to pump it all out, so they take a metal that's reactive to air, and they vapor-deposit (Boil it and then let it settle) it on the inside of the glass, this way any air that's left will be absorbed by the metal and turn into metal nitride, or metal oxide. Barium is perfect for this.

Date added(year-month-day):20110726, sample number:33

Tags(Elements in sample):barium, vacuum

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