Lawrencium
Atomic Data
| Atomic Number | 103 |
| Symbol | Lr |
| Atomic Weight | 266 u |
| Density (STP) | N/A |
| Melting Point | 1626.85 °C (1900 K) |
| Boiling Point | N/A °C (None K) |
| Electronegativity | 1.3 (Pauling) |
| Electron Config. | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 5f14 6s2 6p6 7s2 7p1 |
| Oxidation States | +3 |
| Phase at STP | Solid |
| Category | Actinoid |
| Period / Group | 7 / None |
| CAS Number | 22537-11-7 |
Electron Configuration
[Rn] 5f14 7s2 7p1
| Shell | n | Subshell | Electrons | Cumulative |
|---|---|---|---|---|
| K | 1 | 1s | 2 | 2 |
| L | 2 | 2s | 2 | 4 |
| L | 2 | 2p | 6 | 10 |
| M | 3 | 3s | 2 | 12 |
| M | 3 | 3p | 6 | 18 |
| M | 3 | 3d | 10 | 28 |
| N | 4 | 4s | 2 | 30 |
| N | 4 | 4p | 6 | 36 |
| N | 4 | 4d | 10 | 46 |
| N | 4 | 4f | 14 | 60 |
| O | 5 | 5s | 2 | 62 |
| O | 5 | 5p | 6 | 68 |
| O | 5 | 5d | 10 | 78 |
| O | 5 | 5f | 14 | 92 |
| P | 6 | 6s | 2 | 94 |
| P | 6 | 6p | 6 | 100 |
| Q | 7 | 7s | 2 | 102 |
| Q | 7 | 7p | 1 | 103 |
| Total | 103 | 103 | ||
Isotopes of Lawrencium
Lawrencium has two naturally occurring stable isotopes. The most abundant is ²⁶²Lr, comprising None% of all naturally occurring Lawrencium.
| Isotope | Symbol | Protons | Neutrons | Abundance | Stability |
|---|---|---|---|---|---|
| Lawrencium-262 | ²⁶²Lr | 103 | 159 | trace | Stable |
| Lawrencium-266 | ²⁶⁶Lr | 103 | 163 | trace | Stable |
Abundance & Occurrence
Lawrencium is present in Earth's crust at approximately trace amounts by mass and at approximately trace amounts by mass throughout the universe.
Earth's Crust (ppm by mass)
Universe (ppm by mass)
Discovery & History
Read more about the discovery of the periodic table of elements →
Safety & Handling
- Alpha radiation: Lawrencium isotopes are short-lived alpha emitters (Lr-266, t½ = 11 h is among the longer-lived); production is limited to a few atoms at a time in heavy ion accelerator bombardments.
- No bulk handling: Lawrencium has never been produced in any quantity that could constitute a conventional radiation or chemical hazard; work involves atom-by-atom detection and chemical separation experiments.
- Accelerator facility hazards: The radiation environment at heavy ion accelerators (prompt gamma, neutron activation of targets and beamline) requires full radiation protection controls independent of the element being synthesised.
- Regulatory controls: Production and study of lawrencium takes place under national nuclear regulatory authority licences with comprehensive radiation protection and material accountancy.
Lawrencium in the Real World
Real-World Uses
- Actinide/transition metal borderline chemistry: Lawrencium (Lr-260, Lr-262) is the last actinide; gas-phase and aqueous-phase chemical experiments probe whether Lr behaves as a trivalent actinide or adopts the monovalent or divalent behaviour predicted by relativistic calculations of its anomalous [Rn]5f¹⁴7s²7p¹ electron configuration.
- Nuclear structure at the edge of the actinide series: Decay spectroscopy of Lr isotopes provides data on single-particle orbitals just below the N=152 and Z=103 shell gaps, informing predictions of the island of stability in superheavy elements.
- No commercial applications: Lawrencium is produced in quantities of tens of atoms per experiment and has no applications outside fundamental nuclear and chemical science.
Downloadable Resources
Free periodic table reference sheets for classrooms, study sessions, and laboratory use.
Frequently Asked Questions
What is lawrencium used for?
Lawrencium has no practical applications. It is produced only a few atoms at a time in particle accelerators and used purely for scientific research. Lawrencium is chemically interesting as the last actinide: its electron configuration (with a 7p electron rather than the expected 5f) gives it properties that partly deviate from the rest of the actinide series, providing insight into how electron shells fill at the edge of the known periodic table.
How was lawrencium discovered?
Lawrencium was first synthesised in 1961 by Albert Ghiorso, Torbjørn Sikkeland, Almon Larsh, and Robert Latimer at Berkeley, by bombarding californium with boron ions. The Dubna team in the USSR also produced it in the early 1960s. The element was named after Ernest O. Lawrence, inventor of the cyclotron: the type of particle accelerator used to produce most transuranium elements, and after whom the Lawrence Berkeley National Laboratory is also named.
Is lawrencium radioactive?
Yes, all isotopes of lawrencium are radioactive. The most stable, Lr-266, has a half-life of about 11 hours. Earlier identified isotopes have half-lives of seconds to minutes. Lawrencium is the last member of the actinide series (Z=103) and the heaviest element whose chemistry has been partially studied using ion exchange chromatography.
What is unusual about lawrencium's electron configuration?
Lawrencium is expected by analogy to end the actinide series with a 5f14 6d1 7s2 configuration, but quantum mechanical calculations and some experimental evidence suggest its actual ground state is [Rn] 5f14 7s2 7p1: with an electron in the 7p orbital rather than 6d. This makes it analogous to thallium rather than lutetium in one sense. This deviation from expected filling order is a consequence of relativistic effects that compress the 7s orbitals and raise the energy of the 6d orbitals at very high atomic numbers.