Lawrencium
Lawrencium is a radioactive synthetic element with the symbol Lr (formerly Lw) and atomic number 103. Its most stable isotope is 262Lr, with a half-life of approximately 3.6 hours. Little is known of the chemistry but there is strong evidence for the formation of a trivalent ion in aqueous solution, confirming lawrencium's place as the last member of the actinoids. Although lawrencium is often placed as the last member of the 5f-block, it can also be regarded as the first member of the 6d-block.
| General | |
|---|---|
| Name, Symbol, Number | lawrencium, Lr, 103 |
| Chemical series | transition metals |
| Group, Period, Block | n/a, 7, d |
| Appearance | unknown, probably silvery white or metallic gray |
| Standard atomic weight | [262] g·mol-1 |
| Electrons per shell | 2, 8, 18, 32, 32, 9, 2 |
| Physical properties | |
| Phase | presumably a solid |
| Melting point | -K (-°C, -°F) |
| Atomic properties | |
| Oxidation states | 3 |
| Electronegativity | - (Pauling scale) |
| Ionization energies | 1st: 443.8 kJ/mol |
| 2nd: 1428.0 kJ/mol | |
| 3rd: 2219.1 kJ/mol | |
| Miscellaneous | |
| CAS registry number | 22537-19-5 |
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