Lawrencium (Lr): Electron Configuration and Properties
Lawrencium (Lr): Electron Configuration and Properties
Electron configuration [Rn] 7s2 5f14 7p1 · f-block, actinide series · period 7 · Ar [266]
Lawrencium data
- Atomic number
- 103
- Relative atomic mass
- [266]
- Group
- – (actinide series)
- Period
- 7
- Block
- f
- Category
- Actinide
- Electron configuration
- [Rn] 7s2 5f14 7p1
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 7p1
- Electrons per shell
- 2, 8, 18, 32, 32, 8, 3 (K L M N O P Q)
- Valence electrons
- 3 (in the outer shell)
- Electronegativity (Pauling)
- 1.3
- First ionisation energy
- no data
- Atomic radius (van der Waals)
- no data
- State at room temperature
- Solid
- Melting point
- 1627 °C
- Boiling point
- no data
- Density
- no data
- Common oxidation states
- +3
- Discovered
- 1961
Source: PubChem (NIH, accessed 13 Nov 2026); atomic mass: IUPAC standard atomic weight.
Electron shell diagram
K 2 · L 8 · M 18 · N 32 · O 32 · P 8 · Q 3
Orbital diagram (outer electrons)
About lawrencium
With atomic number 103, lawrencium (Lr) has 103 protons in its nucleus and 103 electrons as a neutral atom. It belongs to the actinide series in period 7 (f-block), usually shown below the main table. The element was discovered in 1961. It is named after Ernest Lawrence, inventor of the cyclotron. Lawrencium is a solid at room temperature, melting at 1627 °C.
Lawrencium electron configuration
The electron configuration of lawrencium is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 7p1, or in short [Rn] 7s2 5f14 7p1. Its electrons occupy 7 shells: K = 2, L = 8, M = 18, N = 32, O = 32, P = 8, Q = 3. As an actinide, lawrencium fills the 5f subshell. Its outer 7s subshell holds 2 electrons; valence electrons for this series are not assigned by the usual group rule. This is an exception to the Aufbau rule: the usual filling order predicts [Rn] 7s2 5f14 6d1, but relativistic effects lower the 7p subshell below 6d. When it forms cations, electrons leave the outermost subshell first: Lr3+ = [Rn] 5f14.
Filling order: 1s2(2) → 2s2(4) → 2p6(10) → 3s2(12) → 3p6(18) → 4s2(20) → 3d10(30) → 4p6(36) → 5s2(38) → 4d10(48) → 5p6(54) → 6s2(56) → 4f14(70) → 5d10(80) → 6p6(86) → 7s2(88) → 5f14(102) → 7p1(103)
Uses of lawrencium
Lawrencium has no practical use outside research, because it can only be made a few atoms at a time in particle accelerators.
Safety
Lawrencium is radioactive. Using, storing or transporting radioactive material requires a licence from the national regulator (BAPETEN in Indonesia). Always read the safety data sheet (SDS) before working with a chemical.
Other actinides
Frequently asked questions
What is the electron configuration of lawrencium?
The electron configuration of lawrencium (Lr, atomic number 103) is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 7p1, or [Rn] 7s2 5f14 7p1 in short. By shell: 2, 8, 18, 32, 32, 8, 3.
How many valence electrons does lawrencium have?
Lawrencium has 3 electrons in its outer shell. For lanthanides and actinides, valence electrons are not assigned by the usual group rule.
Which group and period is lawrencium in?
Lawrencium is in the actinide series, period 7, f-block.
What is the atomic mass of lawrencium?
Lawrencium has no stable isotope, so the mass number of its longest-lived isotope, [266], is given.
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