Actinium
Actinium is a chemical element with the symbol Ac and atomic number 89. Actinium is a silvery, radioactive, metallic element. Due to its intense radioactivity, actinium glows in the dark with a pale blue light. The chemical behavior of actinium is similar to that of the rare earth lanthanum.
| General | |
|---|---|
| Name, Symbol, Number | actinium, Ac, 89 |
| Chemical series | actinides |
| Group, Period, Block | 3, 7, f |
| Appearance | silvery |
| Standard atomic weight | (227) g·mol-1 |
| Electrons per shell | 2, 8, 18, 32, 18, 9, 2 |
| Physical properties | |
| Phase | solid |
| Density (near r.t.) | 10 g·cm−3 |
| Melting point | (circa) 1323K (1050°C, 1922°F) |
| Boiling point | 3471K (3198°C, 5788°F) |
| Heat of fusion | 14 kJ·mol-1 |
| Heat of vaporization | 400 kJ·mol-1 |
| Heat capacity | (25°C) 27.2 J·mol-1·K-1 |
| Atomic properties | |
| Crystal structure | cubic face centered |
| Oxidation states | 3 (neutral oxide) |
| Electronegativity | 1.1 (Pauling scale) |
| Ionization energies | 1st: 499 kJ/mol |
| 2nd: 1170 kJ/mol | |
| Atomic radius | 195 pm |
| Miscellaneous | |
| Magnetic ordering | no data |
| Thermal conductivity | (300K) 12 W·m-1·K-1 |
| CAS registry number | 7440-34-8 |
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