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Lanthanum is a chemical element on the periodic table with the atomic symbol La, atomic number 57, and standard atomic weight 138.91 u. Classified as a Lanthanide within Group 3 and Period 6 (f-block), lanthanum possesses a ground-state electron configuration of [Xe] 5d¹ 6s² distributed across 6 concentric Bohr electron shells (2 · 8 · 18 · 18 · 9 · 2) with 2 outer-shell electrons. Prototype of the lanthanide series. Recently discovered to be an essential catalytic cofactor in pyrroloquinoline quinone (PQQ)-dependent methanol dehydrogenases of extreme acidophilic methanotrophic bacteria.

⚛️ Interactive Periodic Table Lab: Explore Lanthanum (La, Z = 57) in the CRV Science Dynamic Periodic Table & Bohr Orbital Lab to visualize its animated 2 · 8 · 18 · 18 · 9 · 2 electron shells, simulate live phase transitions from 0 K to 6,000 K, and compare periodic heatmaps across all 118 IUPAC elements.

Electron Shell Architecture and Ground-State Configuration

A neutral atom of lanthanum contains 57 protons in its atomic nucleus balanced by 57 electrons occupying quantized atomic orbitals. In the Bohr-Sommerfeld and quantum-mechanical orbital models, these electrons populate 6 principal energy shells (K (n=1): 2e⁻, L (n=2): 8e⁻, M (n=3): 18e⁻, N (n=4): 18e⁻, O (n=5): 9e⁻, P (n=6): 2e⁻), terminating in the seven-orbital f-subshell manifold (azimuthal quantum number l = 3) with ground-state configuration [Xe] 5d¹ 6s². Removing the most loosely bound valence electron from an isolated gaseous lanthanum atom requires a first ionization energy of 538 kJ/mol, while its tendency to attract shared bonding electrons is quantified by a Pauling electronegativity of 1.10.

Periodic Table Position and Neighboring Elements

Within the periodic table, Lanthanum occupies Period 6, Group 3 of the f-block (Lanthanides). Along Period 6, it is flanked by Barium (Ba, Z = 56) and Cerium (Ce, Z = 58). Vertically within its periodic family, Lanthanum shares valence orbital symmetry and homologous chemical trends with Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm). Learners can interactively compare Lanthanum's orbital radii, ionization energy, and Pauling electronegativity against all neighboring elements in the Dynamic Periodic Table Lab.

Standard Phase, Melting Point, and Boiling Point Dynamics

At standard ambient temperature and pressure (298.15 K / 25 °C, 1 atm), elemental lanthanum exists as a crystalline solid. As thermal energy increases, its crystal or molecular lattice undergoes solid-to-liquid fusion at a melting point of 1,193 K (+919.85 °C / +1687.7 °F) and transitions to the vapor phase at a normal boiling point of 3,737 K (+3463.85 °C / +6266.9 °F), spanning a liquid thermodynamic range of 2544 K. In the CRV Science Dynamic Periodic Table, dragging the live temperature slider between absolute zero (0 K) and solar-photosphere temperatures (6,000 K) dynamically tracks Lanthanum's state transitions in real time alongside enthalpy and entropy phase equilibria.

Quantitative Atomic and Thermodynamic Parameter Matrix

Characteristic Oxidation States and Coordination Chemistry

As a 4f-block inner transition metal (rare-earth lanthanide), progressive filling of radially contracted inner 4f orbitals—shielded by outer 5s² 5p⁶ shells—produces the trivalent (+3) lanthanide contraction and sharp f–f optical and magnetic transitions. In chemical compounds, lanthanum exhibits characteristic oxidation states of +3. Depending on the electronegativity difference (Δχ) of its bonding partners—such as Oxygen (χ = 3.44), Fluorine (χ = 3.98), Chlorine (χ = 3.16), Nitrogen (χ = 3.04), Carbon (χ = 2.55), or Hydrogen (χ = 2.20)—lanthanum forms redox-specific oxides, halides, hydrides, or coordination complexes governed by Gibbs free energy (ΔG = ΔH − TΔS).

Nucleosynthesis, Discovery History, and Elemental Origins

First identified or isolated in 1839, Lanthanum carries a distinct cosmological and geochemical signature. With atomic number Z = 57 beyond the iron-56 binding-energy peak, lanthanum is synthesized astrophysically via neutron-capture nucleosynthesis—combining slow neutron capture (the s-process in asymptotic giant branch stars) and rapid neutron capture (the r-process in neutron-star mergers and core-collapse supernovae).

Biochemical Classification: Specialized / Ultra-Trace Bio-Element

In comparative biochemistry and systems physiology, Lanthanum is classified as Specialized / Ultra-Trace Bio-Element. Utilized by specialized lineages (e.g., diatom silica frustules, tunicate vanabins, methanogen nickel cofactors, nitrogenase). Across terrestrial and marine ecosystems, its chemical speciation interacts with enzymes, biogeochemical cycle, phytoplankton, archaea.

Key Mechanistic Functions and Technological Uses

Prototype of the lanthanide series. Recently discovered to be an essential catalytic cofactor in pyrroloquinoline quinone (PQQ)-dependent methanol dehydrogenases of extreme acidophilic methanotrophic bacteria. Researchers and students can further investigate Lanthanum's functional role alongside all 118 elements by launching the Interactive Periodic Table & Element Detective Lab on CRV Science Learn.

What is the electron configuration and valence shell structure of Lanthanum (La)?

Lanthanum (atomic number Z = 57) has the ground-state electron configuration [Xe] 5d¹ 6s², distributing its 57 electrons across 6 shells as 2 · 8 · 18 · 18 · 9 · 2. Its outermost shell contains 2 electrons, placing Lanthanum in Group 3, Period 6 (f-block) as a member of the Lanthanides. You can watch these 57 electrons orbit the nucleus in real time in the Dynamic Periodic Table Bohr Lab.

What phase of matter is Lanthanum at room temperature, and when does it melt or boil?

At standard room temperature (298 K / 25 °C) and 1 atm pressure, Lanthanum is a crystalline solid. It melts at 1,193 K (+919.85 °C / +1687.7 °F) and boils at 3,737 K (+3463.85 °C / +6266.9 °F). Using the 0–6,000 K temperature slider in the Interactive Periodic Table, you can observe Lanthanum's exact solid, liquid, and gas transitions relative to all other elements.

How does Lanthanum function in biochemistry, materials science, and technology?

Prototype of the lanthanide series. Recently discovered to be an essential catalytic cofactor in pyrroloquinoline quinone (PQQ)-dependent methanol dehydrogenases of extreme acidophilic methanotrophic bacteria. In biological systems, it is categorized under Specialized / Ultra-Trace Bio-Element, with principal oxidation states of +3 and a first ionization energy of 538 kJ/mol.