Lawrencium
actinideProperties
| Property | Value |
|---|---|
| Atomic Mass | 266 amu |
| Category | actinide |
| Period | 7 |
| Electron Configuration | [Rn] 5f14 7s2 7p1 |
| Electronegativity | 1.3 (Pauling) |
| Oxidation States | 3 |
| Melting Point | 1900 K (1626.8 °C) |
| Discovered By | Albert Ghiorso, Torbjorn Sikkeland, Almon Larsh, Robert M. Latimer (1961) |
About Lawrencium
Lawrencium closes out the actinide row — element 103, named for Ernest O. Lawrence, the Berkeley physicist whose cyclotron made most of the heavy actinides reachable in the first place. The Berkeley team produced the first atoms in 1961 by firing boron-10 and boron-11 ions at a californium target, and even now Lr exists only as collections of individual atoms that decay before you can weigh them. The most stable isotope, Lr-266, lasts about 11 hours, which is luxurious by superheavy standards. The interesting chemistry is what its outermost electron does: experiments in 2015 measured Lr's first ionization energy and confirmed that the loose electron sits in a 7p orbital, not the 6d slot a naive periodic-table reading would predict. Relativistic effects pull the 7s electrons close to the nucleus and push the 6d up in energy, so the 7p ends up lower. That measurement is one of the cleanest demonstrations anywhere that special relativity reshapes the periodic table at the heavy end.
Fun Fact
Lawrencium's electron configuration defied predictions for decades — its last electron sits in a 7p orbital instead of the expected 6d, a quirk caused by Einstein's relativity affecting electron behavior in extremely heavy atoms.
Common Uses
- Single-atom chemistry experiments on the heaviest actinide
- Probing relativistic effects on electron configurations
- Decay-chain studies for confirming neighboring superheavy elements
- Comparison data for theoretical 7p-block predictions
- No commercial applications