56
Ba
Barium
137.327
Barium (Ba)
Alkaline Earth MetalGroup 2Period 6s-block-block
Barium is a chemical element with symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Because of its high chemical reactivity barium is never found in nature as a free element.
Latin name: Barium
Atomic Number
56
Atomic Mass
137.327 g/mol
Phase (STP)
Solid
Electron Config.
[Xe] 6s²
General
SymbolBa
Atomic Number56
Atomic Mass137.327 g/mol
CategoryAlkaline Earth Metal
Group2
Period6
Blocks-block
Electron Configuration[Xe] 6s²
Valence Electrons2
Coloursilvery-white metallic
CAS NumberCAS7440-39-3
Physical Properties
Phase (STP)Solid
Density3.62 g/cm³
Melting Point726.85°C · 1340.33°F · 1000.00 K
Boiling Point1896.85°C · 3446.33°F · 2170.00 K
Atomic Properties
Atomic Radius253 pm
Electronegativity0.89 Pauling
Ionization Energy503 kJ/mol
Oxidation States+2
Ion ChargeBa2+
Thermodynamic
Molar Heat28.07 J/(mol·K)
Crystal Structure
Crystal Structurebody-centered cubic
Mechanical Properties
Mohs Hardness1.25
Nuclear & Hazards
Half-lifestable
Abundance
In Universe0.00009999999999999999%
In Sun0.00008999999999999999%
In Earth's Crust0.3000%
In Oceans0.000003%
In Meteorites0.0002%
Discovery & History
Discovery Year1808
Discovered ByHumphry Davy
Country of DiscoveryEngland
Isotopes of Barium
| Isotope | Abundance | Half-life | Decay |
|---|---|---|---|
| Ba-130 | 0.106% | Stable | — |
| Ba-132 | 0.101% | Stable | — |
| Ba-134 | 2.417% | Stable | — |
| Ba-135 | 6.592% | Stable | — |
| Ba-136 | 7.854% | Stable | — |
| Ba-137 | 11.232% | Stable | — |
| Ba-138 | 71.698% | Stable | — |