#103 / 118
103Lr[266]
Actinidessolid at STPD-block

Lawrencium

Group: f-blockPeriod: 7Standard Atomic Weight: [266] u

Why is Lawrencium in this position?

Understanding the scientific rationale behind Lawrencium's position in the periodic table:

Group Assignment
Group Lanthanide / Actinide

Final member of the Actinide series bridging the 5f shell into the 6d transactinides (Group 3).

Period Assignment
Period 7

Belongs to Period 7 because its outermost electrons occupy n=7.

Orbital Block
D-block

Electronically a p/d-block bridge ([Rn] 5f¹⁴ 7s² 7p¹), marking the end of the actinide f-block.

Chemical Category
Actinides

Classified as an actinide synthetic metal.

Atomic Structure & Bohr Shell Model

Shell Distribution: [2, 8, 18, 32, 32, 8, 3]

Bohr Atomic Shell Model(2, 8, 18, 32, 32, 8, 3)

Hover or tap any shell orbit ring to inspect electron counts and 2n² capacities.

103 Protons (p⁺)163 Neutrons (n⁰)
KShell K: Electron 1 of 2Shell K: Electron 2 of 2LShell L: Electron 1 of 8Shell L: Electron 2 of 8Shell L: Electron 3 of 8Shell L: Electron 4 of 8Shell L: Electron 5 of 8Shell L: Electron 6 of 8Shell L: Electron 7 of 8Shell L: Electron 8 of 8MShell M: Electron 1 of 18Shell M: Electron 2 of 18Shell M: Electron 3 of 18Shell M: Electron 4 of 18Shell M: Electron 5 of 18Shell M: Electron 6 of 18Shell M: Electron 7 of 18Shell M: Electron 8 of 18Shell M: Electron 9 of 18Shell M: Electron 10 of 18Shell M: Electron 11 of 18Shell M: Electron 12 of 18Shell M: Electron 13 of 18Shell M: Electron 14 of 18Shell M: Electron 15 of 18Shell M: Electron 16 of 18Shell M: Electron 17 of 18Shell M: Electron 18 of 18NShell N: Electron 1 of 32Shell N: Electron 2 of 32Shell N: Electron 3 of 32Shell N: Electron 4 of 32Shell N: Electron 5 of 32Shell N: Electron 6 of 32Shell N: Electron 7 of 32Shell N: Electron 8 of 32Shell N: Electron 9 of 32Shell N: Electron 10 of 32Shell N: Electron 11 of 32Shell N: Electron 12 of 32Shell N: Electron 13 of 32Shell N: Electron 14 of 32Shell N: Electron 15 of 32Shell N: Electron 16 of 32Shell N: Electron 17 of 32Shell N: Electron 18 of 32Shell N: Electron 19 of 32Shell N: Electron 20 of 32Shell N: Electron 21 of 32Shell N: Electron 22 of 32Shell N: Electron 23 of 32Shell N: Electron 24 of 32Shell N: Electron 25 of 32Shell N: Electron 26 of 32Shell N: Electron 27 of 32Shell N: Electron 28 of 32Shell N: Electron 29 of 32Shell N: Electron 30 of 32Shell N: Electron 31 of 32Shell N: Electron 32 of 32OShell O: Electron 1 of 32Shell O: Electron 2 of 32Shell O: Electron 3 of 32Shell O: Electron 4 of 32Shell O: Electron 5 of 32Shell O: Electron 6 of 32Shell O: Electron 7 of 32Shell O: Electron 8 of 32Shell O: Electron 9 of 32Shell O: Electron 10 of 32Shell O: Electron 11 of 32Shell O: Electron 12 of 32Shell O: Electron 13 of 32Shell O: Electron 14 of 32Shell O: Electron 15 of 32Shell O: Electron 16 of 32Shell O: Electron 17 of 32Shell O: Electron 18 of 32Shell O: Electron 19 of 32Shell O: Electron 20 of 32Shell O: Electron 21 of 32Shell O: Electron 22 of 32Shell O: Electron 23 of 32Shell O: Electron 24 of 32Shell O: Electron 25 of 32Shell O: Electron 26 of 32Shell O: Electron 27 of 32Shell O: Electron 28 of 32Shell O: Electron 29 of 32Shell O: Electron 30 of 32Shell O: Electron 31 of 32Shell O: Electron 32 of 32PShell P: Electron 1 of 8Shell P: Electron 2 of 8Shell P: Electron 3 of 8Shell P: Electron 4 of 8Shell P: Electron 5 of 8Shell P: Electron 6 of 8Shell P: Electron 7 of 8Shell P: Electron 8 of 8QShell Q: Electron 1 of 3Shell Q: Electron 2 of 3Shell Q: Electron 3 of 3LrZ = 103

Educational Note: This Niels Bohr planetary model visually illustrates principal quantum energy shells ($n=1, 2, 3\dots$) and electron counts. In modern quantum mechanics (Schrödinger model), electrons do not orbit in fixed circular planetary tracks, but exist as 3D probability clouds (orbitals: $s, p, d, f$) governed by the Heisenberg uncertainty principle.

Electron Shell Filling Breakdown

Shell K (n=1):2 / 2 electrons (100%)
Shell L (n=2):8 / 8 electrons (100%)
Shell M (n=3):18 / 18 electrons (100%)
Shell N (n=4):32 / 32 electrons (100%)
Shell O (n=5):32 / 50 electrons (64%)
Shell P (n=6):8 / 72 electrons (11%)
Shell Q (n=7):3 / 98 electrons (3%)
Aufbau Electron Configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 7s² 7p¹

Neutral ground state configuration. Valence electrons: 3.

Atomic & Quantum Properties

Electronegativity (Pauling)1.3 Pauling
1st Ionization Energy470 kJ/mol
Electron Affinity-30 kJ/mol
Atomic Radius (empirical)161 pm
Common Oxidation States+3
Crystal StructureHCP

Physical & Thermal Properties

Density at STP14.4 g/cm³ (estimated)
Melting Point1627 °C (1900 K)
Boiling Point2200 °C (2473 K)
Magnetic OrderingParamagnetic
Discovery Year1961
Discovered ByAlbert Ghiorso, Torbjørn Sikkeland, Almon Larsh & Robert M. Latimer

Real-World Uses, Occurrence & Compounds

Major Industrial & Everyday Uses
  • Pure research on heavy-element relativistic quantum mechanics and actinide-transactinide transition behavior
Occurrence in Nature

Synthesized in cyclotrons by bombarding Californium targets with Boron-10 and Boron-11 ions.

Etymology & Name Origin

Named in honor of Ernest O. Lawrence, inventor of the cyclotron particle accelerator and founder of Berkeley Lab

Important Chemical Compounds
LrCl₃ (Lawrencium trichloride)
Interesting Chemical Facts
  • Lawrencium has an unprecedented electronic anomaly: its valence electron occupies the 7p orbital instead of the 6d orbital because relativistic effects shrink and stabilize the 7p₁/₂ subshell.
  • Because of its 7p¹ valence electron, Lawrencium has a lower ionization energy (4.96 eV / 470 kJ/mol) than sodium and calcium.
  • Ernest Lawrence won the 1939 Nobel Prize in Physics for inventing the circular cyclotron accelerator that enabled transuranic discoveries.
Safety & Handling Note

Radioactive alpha emitter; handled atom-by-atom in accelerator gas-jet recoil chambers.