Lawrencium
Actinide · Period 7 · Group 3 · d-block
The last actinide, with an electron where nobody expected it
- Atomic mass
- 266 u
- State at 25 °C
- Solid
- Electronegativity
- 1.3
- Melting point
- 1,626.9 °Cpredicted
- Boiling point
- —
- Configuration
- [Rn] 5f14 7s2 7p1
Nucleus drawn at reduced count for clarity. Drag to rotate.
Lawrencium, explained
Video lesson in production
Bhavya’s explainer for this element will play here.
Overview
Lawrencium closes the actinide series. Its ion chemistry is ordinary: in water it forms only Lr3+, behaving like the trivalent late actinides and lanthanides such as lutetium. Its electron configuration is not ordinary. Relativistic effects, which become large in heavy atoms because inner electrons move at a sizable fraction of the speed of light, are predicted to place its outermost electron in a 7p orbital, giving 7s2 7p1 rather than the 6d1 seen in lutetium's analog.
In 2015 a team at the Japan Atomic Energy Agency measured lawrencium's first ionization energy, 4.96 eV, using single atoms that were ionized on a hot tantalum surface. The value was the lowest of any actinide and matched relativistic calculations, supporting the weakly bound outer electron. That result also sharpened an ongoing debate about whether lawrencium and lutetium, or lanthanum and actinium, belong in group 3 of the periodic table.
Discovery
Albert Ghiorso, Torbjørn Sikkeland, Almon Larsh and Robert Latimer at Berkeley announced element 103 in 1961 after bombarding a mixed californium target with boron-10 and boron-11 ions; their isotope assignment was later corrected. Dubna's group under Georgy Flerov published more rigorous work from 1965 onward. IUPAC credited both labs in 1992. The name honors Ernest Lawrence, inventor of the cyclotron and founder of the Berkeley laboratory.
- Where it’s found
- Lawrencium does not occur in nature; it is made in accelerators by fusing light ions such as boron, oxygen or nitrogen with actinide targets.
- What it’s used for
- Ionization energy studies
- Group 3 placement debate
- Relativistic effects research
- Nuclear structure research
- In living things
- Lawrencium has no biological role. It is radioactive and exists only as single atoms in the laboratory.
- Safety
- Radioactive and produced only atom by atom; it is never present in amounts that pose a hazard outside the accelerator.
How it compares
Where Lawrencium sits among all 118 elements on the trends that shape the table.
- Electronegativity1.3Pauling
#62 of 100 elements with data · predicted
- Ionization energy470kJ/mol
#100 of 104 elements with data · predicted
- Atomic radiusNo data
Not measured for this element
- Electron affinity-30kJ/mol
#93 of 109 elements with data · predicted
- DensityNo data
Not measured for this element
- Melting point1,900K
#22 of 110 elements with data · predicted
- Density
- —
- Atomic radius
- —
- Covalent radius
- —
- Molar heat
- —
- Appearance
- —
- Discovered by
- Lawrence Berkeley National Laboratory
Inside the atom
103 electrons arranged in 7 shells: 2 · 8 · 18 · 32 · 32 · 8 · 3.
Orbital diagram
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 7p1 · shorthand [Rn] 5f14 7s2 7p1
- 1s2
- 2s2
- 2p6
- 3s2
- 3p6
- 4s2
- 3d10
- 4p6
- 5s2
- 4d10
- 5p6
- 6s2
- 4f14
- 5d10
- 6p6
- 7s2
- 5f14
- 7p1
Each box is an orbital holding up to two electrons of opposite spin. Highlighted subshells hold the valence electrons that decide how Lawrencium bonds.
Signature reactions
How the first atoms were made, and how they fall apart.
Nuclear · Fusion-evaporation
Dubna synthesis
Oxygen-18 fuses with americium-243, and the compound nucleus sheds five neutrons to give lawrencium-256. Dubna's identification of this isotope was part of the work that earned the lab shared discovery credit.
Conditions: oxygen-18 beam on americium target, Dubna, 1965
Nuclear · Fusion-evaporation
Berkeley synthesis
Boron ions striking californium produced lawrencium isotopes that recoiled onto a moving tape and were carried past detectors. The 1961 team first assigned the activity to lawrencium-257; it was later attributed to lawrencium-258.
Conditions: boron beam on californium isotopes, Berkeley HILAC, 1961
Complexation · Extraction
Solvent extraction of Lr(III)
In 1970 Silva and co-workers showed that lawrencium extracts from water into an organic phase with the chelating agent thenoyltrifluoroacetone at the same pH as trivalent actinides. This measured result established that Lr behaves as a 3+ ion in solution.
Conditions: thenoyltrifluoroacetone (HTTA), controlled pH, tracer scale
Where you’ll meet it
Cyclotron
Lawrence's spiraling particle accelerator made the synthesis of transuranium elements possible.
Photo: Wikimedia Commons
Lawrence Berkeley National Laboratory
The lab Lawrence founded announced element 103 in 1961.
Photo: Wikimedia Commons
Joint Institute for Nuclear Research
Dubna's careful lawrencium experiments earned it a share of the discovery credit.
Photo: Wikimedia Commons
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Research
No research on Lawrencium yet
When Bhavya publishes a project that studies Lawrencium, it will be linked here.