| Symbol | Ba |
| Atomic number | 56 |
| Group | 2 (Alkaline earth metal) |
| Period | 6 |
| Block | s |
| Classification | Alkaline Earth Metal |
| Appearance | - |
| Color | Silver |
| Number of protons | 56 p+ |
| Number of neutrons | 81 n0 |
| Number of electrons | 56 e- |
| Phase at STP | Solid |
| Density | 3.51 g/cm3 |
| Atomic weight | 137.328 u |
| Melting point | 1000 K 726.85 °C 1340.33 °F |
| Boiling point | 2118 K 1844.85 °C 3352.73 °F |
| Heat of vaporization | 140.2 kJ/mol |
| Electronegativity (Pauling Scale) | 0.89 |
| Electron affinity | 13.954 kJ/mol |
| Oxidation states | +1, +2 (a strongly basic oxide) |
| Ionization energies |
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| Discovery | Carl Wilhelm Scheele (1772) |
| First isolation | Humphry Davy (1808) |
Discovery of barium Alchemists in the early Middle Ages knew about some barium minerals. Smooth pebble-like stones of mineral baryte were found in volcanic rock near Bologna, Italy, and so were called "Bologna stones". Alchemists were attracted to them because after exposure to light they would glow for years. The phosphorescent properties of baryte heated with organics were described by V. Casciorolus in 1602. Carl Scheele determined that baryte contained a new element in 1774, but could not isolate barium, only barium oxide. Johan Gottlieb Gahn also isolated barium oxide two years later in similar studies. Oxidized barium was at first called "barote" by Guyton de Morveau, a name that was changed by Antoine Lavoisier to baryta. Barium was first isolated by electrolysis of molten barium salts in 1808 by Sir Humphry Davy in England. Davy, by analogy with calcium, named "barium" after baryta, with the "-ium" ending signifying a metallic element. | |