Lawrencium (symbol Lr, atomic number 103) is the final actinide, a synthetic element produced atom by atom. It is classified as a actinide and sits in the actinide series (f-block), period 7 of the periodic table.
Overview
Lawrencium is the chemical element with atomic number 103 and the symbol Lr. With a standard atomic weight of [266], it is a actinide. In the periodic table it occupies the actinide series (f-block) and period 7, and under standard conditions it is normally a solid. Lawrencium is the final actinide, a synthetic element produced atom by atom.
Atomic structure
An atom of Lawrencium has 103 protons in its nucleus and, when neutral, 103 electrons arranged in the configuration [Rn] 5f14 7s2 7p1. Lawrencium has no stable isotope; the value [266] refers to the mass number of its most stable or most commonly produced isotope.
Discovery and place in the table
Lawrencium was discovered in 1961 by Lawrence Berkeley National Laboratory. It follows Nobelium (No) and precedes Rutherfordium (Rf) in order of atomic number.
| Atomic number | 103 |
|---|---|
| Symbol | Lr |
| Atomic mass | [266] |
| Category | Actinide |
| Group | — |
| Period | 7 |
| Electron configuration | [Rn] 5f14 7s2 7p1 |
| Phase at STP | Solid |
| Discovered | 1961 (Lawrence Berkeley National Laboratory) |