Barium

Symbol: Ba
Atomic number: 56
Category: alkaline earth metals
Group: 2
Period: 6
Block: s
Atomic weight: 137.327 g/mol
Electrons per shell: 2, 8, 18, 18, 8, 2
CAS number: 7440-39-3
Phase: solid
Density: 3.51 kg/dm³ (near room temperature)
Melting point: 1000 K (727 °C, 1341 °F)
Boiling point: 2170 K (1897 °C, 3447 °F)
Crystal structure: face centered cubic
Oxidation states: 2
Electronegativity: 0.89 (Pauling scale)
Name's origin: bary
Name's meaning: heavy
Facts:
- is never found in nature in its pure form due to its reactivity with air
- all water or acid soluble barium compounds are extremely poisonous
- oxidation occurs very easily and, to remain pure barium should be kept under a petroleum- based fluid (such as kerosene) or other suitable oxygen-free liquids that exclude air