Lawrencium
[Rn] 5f¹⁴ 7s² 7p¹ · 2 · 8 · 18 · 32 · 32 · 8 · 3
The last actinide, and the element where theory and experiment part company over electron configuration: calculations predict 7p¹ rather than the expected 6d¹ — relativity showing up in atomic structure.
3D model
Bohr model: nucleus and electron shells from the real configuration. Valence electrons are highlighted.
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Atomic properties
- Atomic number
- 103
- Atomic mass
- 266 а.е.м. ≈
- Electron configuration
- [Rn] 5f¹⁴ 7s² 7p¹
- Electrons per shell
- 2 · 8 · 18 · 32 · 32 · 8 · 3
- Block
- p-block
- Group
- no data
- Period
- 7
- Electronegativity (Pauling)
- 1.3
- Electronegativity (Allen)
- 1.3
- Atomic radius
- 246 pm
- Covalent radius
- 161 pm
- Van der Waals radius
- 246 pm
- Ionisation energy 1
- 478.6 kJ/mol
- Electron affinity
- -33.77 kJ/mol
- Common oxidation states
- +3
- Oxidation states
- +3
Physical properties
- State at 25 °C
- solid
- Density
- 15.6 g/cm³ ≈
- Melting point
- 1 900 K · 1 626.9 °C ≈
- Boiling point
- no data
- Speed of sound
- no data
Thermal properties
- Heat of fusion
- no data
- Heat of vaporisation
- no data
- Specific heat capacity
- no data
- Thermal conductivity
- no data
Mechanical properties
- Young's modulus
- no data
- Shear modulus
- no data
- Bulk modulus
- no data
- Poisson ratio
- no data
- Mohs hardness
- no data
- Brinell hardness
- no data
Electrical and magnetic properties
- Electrical resistivity
- no data
- Magnetic ordering
- paramagnetic
- Curie point
- no data
- Néel point
- no data
- Superconducting point
- no data
Crystal structure
- Crystal structure
- hexagonal close-packed (hcp) ≈
- Lattice constants
- no data
Abundance
- In the crust
- 0 mg/kg
- In the ocean
- 0 mg/L
- In the universe
- 0 mg/kg
- In the human body
- 0 mg/kg
Isotopes
| Isotope | Abundance | Half-life | Decay mode |
|---|---|---|---|
| 262Lr | — | 3.61 h | ЭЗ |
| 266Lr | — | 11 h | СД |
Lawrencium-266, half-life about 11 hours, is the longest-lived known isotope.
Discovery
- Year of discovery
- 1961
- Discovered by
- Berkeley and Dubna
- Where
- USA and USSR
- Origin of the name
- after Ernest Lawrence, inventor of the cyclotron
History
Ghiorso and colleagues claimed the synthesis at Berkeley in 1961 and Dubna in 1965. IUPAC awarded joint priority in 1997. It is named after Ernest Lawrence, inventor of the cyclotron.
Where it occurs
Absent from nature.
How it is produced
By nuclear fusion: californium bombarded with boron ions, or americium with oxygen. It is made one atom at a time.
Role in living things
No biological role.
Safety
Only single atoms are ever handled.
Uses
Fundamental research: measuring lawrencium's ionisation energy in 2015 was a test of relativistic calculations
Curiosities
- Lawrencium's ionisation energy was measured in 2015 from a handful of atoms and proved the lowest of any actinide.
- Lawrencium's outer electron sits in a 7p orbital rather than 6d, because of relativistic effects.
- That is precisely why many modern tables place lawrencium in group 3 alongside lutetium.
- The Lawrence cyclotron that named the element made almost every transuranium discovery possible.