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| Physical Properties | ||
|---|---|---|
| Color | silvery-white | |
| Phase at Room Temp. | solid | |
| Density (g/cm3) | 7.003 | |
| Hardness (Mohs) | --- | |
| Melting Point (K) | 1283.2 | |
| Boiling Point (K) | 3300 | |
| Heat of Fusion (kJ/mol) | 7.1 | |
| Heat of Vaporization (kJ/mol) | 289 | |
| Heat of Atomization (kJ/mol) | 328 | |
| Thermal Conductivity (J/m sec K) | 16.5 | |
| Electrical Conductivity (1/mohm cm) | 15.4 | |
| Source | Monazite (phosphate), bastnaesite | |
| Atomic Properties | ||
| Electron Configuration | [Xe]6s24f4 | |
| Number of Isotopes | 41 (7 natural) | |
| Electron Affinity (kJ/mol) | 50 | |
| First Ionization Energy (kJ/mol) | 529.6 | |
| Second Ionization Energy (kJ/mol) | 1035 | |
| Third Ionization Energy (kJ/mol) | 2130 | |
| Electronegativity | 1.14 | |
| Polarizability (Å3) | 31.4 | |
| Atomic Weight | 144.24 | |
| Atomic Volume (cm3/mol) | 20.6 | |
| Ionic Radius2- (pm) | --- | |
| Ionic Radius1- (pm) | --- | |
| Atomic Radius (pm) | 181 | |
| Ionic Radius1+ (pm) | --- | |
| Ionic Radius2+ (pm) | --- | |
| Ionic Radius3+ (pm) | 112.3 | |
| Common Oxidation Numbers | +3 | |
| Other Oxid. Numbers | +2 | |
| Abundance | ||
| In Earth's Crust (mg/kg) | 4.15x101 | |
| In Earth's Ocean (mg/L) | 2.8x10-6 | |
| In Human Body (%) | --- | |
| Regulatory / Health | ||
| CAS Number | 7440-00-8 | |
| OSHA Permissible Exposure Limit (PEL) | No limits | |
| OSHA PEL Vacated 1989 | No limits | |
| NIOSH Recommended Exposure Limit (REL) | No limits | |
| Sources: University of Wisconsin General Chemistry Mineral Information Institute Jefferson Accelerator Laboratory EnvironmentalChemistry.com | ||

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