Discovery date : 1808
Discovered by: Humphry Davy
Origin of the name: The name comes from the Greek 'barys', meaning heavy.
Allotropes :
~>BARIUM is a chemical element with symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element.
| FACT BOX | |||
| Group | 2 | Melting point | 727°C, 1341°F, 1000 K |
| Period | 6 | Boiling point | 1845°C, 3353°F, 2118 K |
| Block | p | Density (g cm−3) | 3.62 |
| Atomic number | 56 | Relative atomic mass | 137.327 |
| State at 20°C | Solid | Key isotopes | 138Ba |
| Electron configuration | [Xe] 6s2 | CAS number | 7440-39-3 |
| ChemSpider ID | 4511436 | ChemSpider is a free chemical structure database | |
In the early 1600s, Vincenzo Casciarolo, of Bologna, Italy, found some unusual pebbles. If they were heated to redness during the day, they would shine during the night. This was the mineral barite (barium sulfate, BaSO4).
When Bologna stone, as it became known, was investigated by Carl Scheele in 1760s he realised it was the sulfate of an unknown element. Meanwhile a mineralogist, Dr William Withering, had found another curiously heavy mineral in a lead mine in Cumberland which clearly was not a lead ore. He named it witherite; it was later shown to be barium carbonate, BaCO3.
Neither the sulfate nor the carbonate yielded up the metal itself using the conventional process of smelting with carbon. However, Humphry Davy at the Royal Institution in London produced it by the electrolysis of barium hydroxide in 1808.