Barium (symbol Ba, atomic number 56) is an alkaline earth metal whose sulfate is swallowed for X-ray contrast imaging. It is classified as a alkaline earth metal and sits in group 2, period 6 of the periodic table.
Overview
Barium is the chemical element with atomic number 56 and the symbol Ba. With a standard atomic weight of 137.33, it is a alkaline earth metal. In the periodic table it occupies group 2 and period 6, and under standard conditions it is normally a solid. Barium is an alkaline earth metal whose sulfate is swallowed for X-ray contrast imaging.
Atomic structure
An atom of Barium has 56 protons in its nucleus and, when neutral, 56 electrons arranged in the configuration [Xe] 6s2. Its standard atomic weight of 137.33 reflects the natural mix of its stable isotopes.
Discovery and place in the table
Barium was discovered in 1808 by Humphry Davy. It follows Caesium (Cs) and precedes Lanthanum (La) in order of atomic number.
| Atomic number | 56 |
|---|---|
| Symbol | Ba |
| Atomic mass | 137.33 |
| Category | Alkaline earth metal |
| Group | 2 |
| Period | 6 |
| Electron configuration | [Xe] 6s2 |
| Phase at STP | Solid |
| Discovered | 1808 (Humphry Davy) |