Protactinium

Protactinium is a chemical element with the symbol Pa and atomic number 91.
General | |
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Name, Symbol, Number | protactinium, Pa, 91 |
Chemical series | actinides |
Group, Period, Block | n/a, 7, f |
Appearance | bright, silvery metallic luster |
Standard atomic weight | 231.03588(2) g·mol-1 |
Electrons per shell | 2, 8, 18, 32, 20, 9, 2 |
Physical properties | |
Phase | solid |
Density (near r.t.) | 15.37 g·cm−3 |
Melting point | 1841K (1568°C, 2854°F) |
Boiling point | ? 4300K (? 4027°C, ?°F) |
Heat of fusion | 12.34 kJ·mol-1 |
Heat of vaporization | 481 kJ·mol-1 |
Atomic properties | |
Crystal structure | orthorhombic |
Oxidation states | 2, 3, 4, 5 (weakly basic oxide) |
Electronegativity | 1.5 (Pauling scale) |
Ionization energies | 1st: 568 kJ/mol |
Atomic radius | 180 pm |
Miscellaneous | |
Magnetic ordering | no data |
Electrical resistivity | (0 °C) 177 nΩ·m |
Thermal conductivity | (300K) 47 W·m-1·K-1 |
CAS registry number | 7440-13-3 |

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