Barium
Definition and meaning of Barium in chemistry.
Barium is a soft, dense, silvery alkaline earth metal with the symbol Ba and atomic number 56. It is highly chemically reactive, meaning it is never found in nature as a free element and must be carefully extracted from specific mineral deposits.
In more detail
Situated in group 2 of the periodic table, barium is a heavy, reactive metal that rapidly oxidizes upon exposure to air to form a dark gray, passivating layer of barium oxide (BaO). It reacts violently with water and various alcohols to release highly combustible hydrogen gas (H2), necessitating strict storage under mineral oil or a completely inert atmosphere to prevent degradation and accidental fires. Barium primarily occurs in nature in the highly insoluble minerals barite (barium sulfate, BaSO4) and witherite (barium carbonate, BaCO3). Due to its high chemical reactivity and strong affinity for oxygen and nitrogen, metallic barium is frequently used as a getter material in vacuum tubes to effectively remove unwanted trace gases. All water-soluble compounds of barium are highly toxic to humans and animals because the Ba2+ ion acts as a competitive antagonist, fatally blocking essential potassium ion channels in the nervous system.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Ba |
| Atomic number | 56 |
| Atomic mass | 137.33 u |
| Category | Alkaline Earth Metal |
| State at room temperature | Solid |
| Melting point | 727 °C |
| Boiling point | 1897 °C |
| Year discovered | 1774 |
A thick suspension of barium sulfate is used globally as a safe radiocontrast agent in specialized medical imaging procedures (often called a barium swallow) to help doctors accurately diagnose structural abnormalities in the digestive tract because the dense heavy metal powerfully blocks X-rays.
Frequently asked questions
If barium ions are highly toxic, why is it safe for patients to swallow barium for medical X-rays?
The specific compound used, barium sulfate, is exceptionally insoluble in both water and harsh stomach acid, meaning it simply passes safely through the entire digestive tract without any toxic Ba2+ ions being absorbed into the patient's bloodstream.
What specific color does barium impart to a flame during a flame test?
Barium and its various chemical salts impart a characteristic bright, vivid apple-green color to flames, making them incredibly popular and essential active components in the manufacturing of commercial pyrotechnics and green fireworks.