Barium (Ba)

Barium is a soft, silvery alkaline earth metal that never occurs in nature as a free element.

Core Principles & Analysis

• Humphry Davy first isolated barium metal in 1808 by electrolysis, decades after Scheele distinguished its oxide in 1774.
• Its name comes from the Greek for heavy, after the dense mineral barite, and its salts burn with a distinctive green flame.
• Insoluble barium sulfate is swallowed as the 'barium meal' contrast agent for X-ray imaging of the digestive tract and weights oil-drilling muds.

Specifications & Metrics

• NUM: 56
• SYMBOL: Ba
• CATEGORY: Alkaline Earth Metal
• ATOMIC MASS: 137.33 u
• ELECTRONEGATIVITY: 0.89 Pauling
• ATOMIC RADIUS: 268 pm
• IONIZATION ENERGY: 5.212 eV
• MELTING POINT: 1000 K
• BOILING POINT: 2170 K
• DENSITY: 3.62 g/cm³
• ELECTRON CONFIGURATION: [Xe]6s2
• OXIDATION STATES: +2
• STANDARD STATE: Solid
• GROUP BLOCK: Alkaline earth metal
• YEAR DISCOVERED: 1808