Barium
From The Encyclopedia of Earth
January 4, 2007, 12:00 am
November 2, 2011, 4:00 pm
| Previous Element: Cesium Next Element: Lanthanum |
| |
| Physical Properties | ||
|---|---|---|
| Color | silvery-white | |
| Phase at Room Temp. | solid | |
| Density (g/cm3) | 3.62 | |
| Hardness (Mohs) | --- | |
|
Melting Point (K) |
998.2 | |
|
Boiling Point (K) |
2123 | |
| Heat of Fusion (kJ/mol) | 7.657 | |
| Heat of Vaporization (kJ/mol) | 151 | |
| Heat of Atomization (kJ/mol) | 180 | |
| Thermal Conductivity (J/m sec K) | 18.4 | |
| Electrical Conductivity (1/mohm cm) | --- | |
| Source | Barite (sulfate) | |
| Atomic Properties | ||
| Electron Configuration | [Xe]6s2 | |
|
Number of Isotopes |
48 (7 natural) | |
| Electron Affinity (kJ/mol) | --- | |
| First Ionization Energy (kJ/mol) | 502.9 | |
| Second Ionization Energy (kJ/mol) | 965.2 | |
| Third Ionization Energy (kJ/mol) | --- | |
| Electronegativity | 0.89 | |
| Polarizability (Å3) | 39.7 | |
| Atomic Weight | 137.33 | |
| Atomic Volume (cm3/mol) | 37.9 | |
| Ionic Radius2- (pm) | --- | |
| Ionic Radius1- (pm) | --- | |
| Atomic Radius (pm) | 222 | |
| Ionic Radius1+ (pm) | --- | |
| Ionic Radius2+ (pm) | 149 | |
| Ionic Radius3+ (pm) | --- | |
| Common Oxidation Numbers | +2 | |
| Other Oxid. Numbers | --- | |
| Abundance | ||
| In Earth's Crust (mg/kg) | 4.25×102 | |
| In Earth's Ocean (mg/L) | 1.3×10-2 | |
| In Human Body (%) | 0.00003% | |
| Regulatory / Health | ||
| CAS Number | 7440-39-3 | |
| OSHA Permissible Exposure Limit | No limit | |
| OSHA PEL Vacated 1989 | No limit | |
|
NIOSH Recommended Exposure Limit |
No limit | |
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Sources: |
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Barium is a the chemical element with atomic number 56. Barium, with the periodic table symbol Ba, is the fifth element in Group 2; this element presents as a soft silvery metallic alkaline earth metal. Barium does not occur naturally in a pure form due to its very high chemical reactivity with the atmosphere. Its oxide is termed Barium hydroxide, although this molecule reacts with water and carbon dioxide and does not occur as a mineral in the Earth's crust or atmosphere.
| This article is written at a definitional level only. Authors wishing to improve this entry are inivited to expand the present treatment, which additions will be peer reviewed prior to publication of any expansion. |
