Lawrencium (103)

Lawrencium (103) is a synthetic "rare earth metal" which does not occur in the environment, and is represented by the symbol Lr (formerly Lw as suggested by the discovering team). In the periodic table of the elements, it is a period 7 d-block element and the last element of the actinide series. Chemistry experiments have confirmed that lawrencium behaves as the heavier homologue to lutetium and is chemically similar to other actinides.

Name: Lawrencium Symbol: Lr Atomic number: 103 Atomic weight: [ 262 ] Standard state: presumably a solid at 298 K CAS Registry ID: 22537-19-5

Group in periodic table: 3 Group name: (none) Period in periodic table: 7 Block in periodic table: d-block Color: unknown, but probably metallic and silvery white or grey in appearance Classification: Metallic

Historical information

Lawrencium was discovered by Albert Ghiorso, Torbjorn Sikkeland, Almon Larsh, and Robert M. Latimer at 1961 in the United States, at the University of Berkeley. Lawrencium was named after Ernest O. "Lawrence", inventor of the cyclotron particle accelerator, which has given rise to the discovery of most of the rare earth metals. It was given the symbol Lw by the discovery team, but the IUPAC decided in 1963 to change the symbol to the current ‘Lr.’

Element 103, lawrencium, was discovered in 1961 by Ghiorso and others in Berkeley, California, USA, who bombarded a californium target with boron ions. They obtained perhaps two micrograms. Several lawrencium isotopes including those with masses 253, 254, 255, 256, 257, 258, 259, and 260 are known now.

Physical properties

• Melting point: about 1900 [or 1627 °C (2961 °F)] K
• Boiling point: no data K
• Density of solid: no data kg m^-3

Orbital properties

• Ground state electron configuration:  [Rn].5f¹⁴.7s².7p¹ (tentative)
• Shell structure:  2.8.18.32.32.9.2
• Term symbol:   ²P_1/2 (tentative)