Atomic / phase data
Reference atomic and phase values are source-reviewed.
Material structure
The ordinary elemental structure is measured/reviewed; the viewer is a teaching representation.
Element vs material uses
Uses distinguish elemental metal from compounds, alloys, doped hosts or isotope-specific systems.
Geography
Discovery/supply context is selective and does not fabricate deposits, facilities or inventories.
The lens describes evidence status, not confidence theatre. “Unknown” is kept unknown, and teaching schematics are not presented as direct measurements.
Lanthanum (La)
Lanthanum is element 57, a soft rare-earth metal whose La³⁺ chemistry connects the start of the lanthanide series to optical glass, catalysts, battery alloys and hydrogen-storage materials.
Lanthanum atomic number, mass, electron configuration and key properties
Lanthanum: quick answers
How many protons, neutrons and electrons does lanthanum have?
Lanthanum’s atomic number is 57, so every lanthanum atom has 57 protons, and a neutral atom also has 57 electrons. Its most common natural isotope, lanthanum-139, has 82 neutrons (other isotopes have different neutron counts).
What is the symbol for lanthanum?
The chemical symbol for lanthanum is La.
Is lanthanum a solid, liquid or gas at room temperature?
Lanthanum is a solid at room temperature (about 25 °C).
What family (group) is lanthanum in?
Lanthanum is a lanthanide, in group 3, period 6 of the periodic table.
What is the electron configuration of lanthanum?
The ground-state electron configuration of lanthanum is [Xe] 5d¹ 6s².
From atomic number to chemistry
Read these as a chain of causes, not as isolated facts. Each step links to the concept hub if you want the underlying idea explained.
57 protons define lanthanum.
The ground-state configuration frames atomic and chemical behavior.
Periodic position organizes recurring chemistry and trends.
The teaching nucleus is one isotope, not the relative atomic mass.
Phase claims preserve source-reviewed evidence and material context.
Lanthanum in its period and family
Lanthanum begins the lanthanide series in Period 6. Its [Xe] 5d¹6s² ground state readily gives La³⁺, leaving a xenon-like ion and chemistry dominated by the +3 state.
Lanthanum Visual Lab
Explore La across the teaching nucleus, isolated-atom orbitals, evidence-aware material structure and temperature/evidence views, then connect those models to uses, isotopes, search-led questions and source-backed context.
Every mark points to one exact feature
The numbered markers explain the same information system used throughout Element Lookup. Unknown or predicted fields remain visibly labelled rather than being replaced with guesses.
Lanthanum in one minute
Atomic number 57 means every lanthanum nucleus has 57 protons.
Neutral Lanthanum has the ground-state configuration [Xe] 5d¹ 6s².
The representative teaching isotope is ¹³⁹La.
Lanthanum metal, La³⁺ ions and lanthanum-containing glass, catalysts or battery alloys are different material contexts.
The ordinary material reference is Double hexagonal close-packed (DHCP) reference.
Shell rings organize electron counts. They are not electron trajectories or orbital shapes.
2 · 8 · 18 · 18 · 9 · 2 electrons
The displayed d and s orbitals are isolated-atom probability teaching models. They are not metallic bands, bonding orbitals or measured electron-density maps of the bulk material.
Lanthanum is commonly described by a DHCP ordinary-temperature structure. Temperature-dependent allotropy exists; this viewer shows only the ordinary structural reference rather than pretending one lattice persists to melting.. The viewer is evidence-aware: measured structures are identified as such; unknown bulk structures stay unknown.
Teaching visualization; not a literal finite sample or thermal trajectory.What this model does—and does not—show
The displayed d and s orbitals are isolated-atom probability teaching models. They are not metallic bands, bonding orbitals or measured electron-density maps of the bulk material.
Where do I meet lanthanum?
Clickable learning cards connect the element to materials, environment, technology, biology or research - depending on what the evidence actually supports.
Optical glass
Lanthanum oxide is used in specialty optical glasses with high refractive index; the useful glass is a compound mixture, not La metal.
5d¹6s² → La³⁺ → rare-earth materials
Lanthanum is chemically dominated by La³⁺. Its practical uses mostly belong to lanthanum compounds and intermetallic/alloy systems rather than pure La metal.
[Xe] 5d¹6s²
Three outer electrons are readily removed.
Lanthanum in periodic context
Compare nearby or family-related elements without treating a trend as a substitute for element-specific evidence.
| Atomic number | 56 |
|---|---|
| Series | lanthanide |
| Atomic number | 57 |
|---|---|
| Series | lanthanide |
| Atomic number | 58 |
|---|---|
| Series | lanthanide |
Lanthanum properties: atomic, physical, thermal and chemical
Categories follow the science of this element rather than a fixed decorative template. Each row carries condition/provenance context and an evidence label; unknown values stay unknown.
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Atomic number | 57 | Source-reviewed; see Sources below | Evaluated |
| Relative atomic mass | 138.905 | Source-reviewed; see Sources below | Evaluated |
| Ground-state electron configuration | [Xe] 5d¹ 6s² | Source-reviewed; see Sources below | Evaluated |
| Group / period / block | Group Lanthanide · Period 6 · d-block | Periodic-table placement | Evaluated |
| Electronegativity | 1.10 | Source-reviewed; see Sources below | Evaluated |
| Reference isotope | ¹³⁹La | Source-reviewed; see Sources below | Evaluated |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| State context | Soft silvery-white reactive rare-earth metal | Source-reviewed; see Sources below | Evaluated |
| Density | 6.15 g/cm³ | Source-reviewed; see Sources below | Evaluated |
| Material / molecular structure | Double hexagonal close-packed (DHCP) reference | Lanthanum is commonly described by a DHCP ordinary-temperature structure. Temperature-dependent allotropy exists; this viewer shows only the ordinary structural reference rather than pretending one lattice persists to melting. | Measured |
| Classification | Lanthanide / rare-earth metal | Periodic-table / chemistry classification | Evaluated |
| Structure-model scope | Lanthanum is commonly described by a DHCP ordinary-temperature structure. Temperature-dependent allotropy exists; this viewer shows only the ordinary structural reference rather than pretending one lattice persists to melting. | Teaching visualization; exact crystallographic coordinates are not implied unless stated. | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Melting / transition reference | 1193 K | Source-reviewed; see Sources below | Evaluated |
| Boiling / gas reference | 3737 K | Source-reviewed; see Sources below | Evaluated |
| Phase-path context | At approximately standard pressure, lanthanum is treated as a solid below 1193 K, liquid between melting and approximately 3737 K, and gas above the boiling reference. The ordinary crystal label applies to the stated material reference; unmodeled solid allotropy is not fabricated. | Shared phase registry drives the slider, regions and markers. | Evaluated |
| Condition warning | Temperature and pressure define phase behavior; purity/allotropy may matter. | Teaching condition statement | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Common oxidation states | +3 | Source-reviewed; see Sources below | Evaluated |
| Ion / common ion context | La³⁺ | Source-reviewed; see Sources below | Evaluated |
| Periodic chemistry context | Lanthanum begins the lanthanide series in Period 6. Its [Xe] 5d¹6s² ground state readily gives La³⁺, leaving a xenon-like ion and chemistry dominated by the +3 state. | Element-specific interpretation | Reviewed |
| Chemistry caution | Elemental form, ions and compounds are distinct chemical objects. | Interpretive teaching rule | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| ¹³⁹La | Dominant natural isotope | Stable and overwhelmingly abundant in natural lanthanum. | Evaluated |
| ¹³⁸La | Trace natural radioisotope | Very long-lived and naturally occurring. | Evaluated |
| Natural lanthanum | Two-isotope natural mixture | The relative atomic mass is abundance-weighted. | Evaluated |
| Teaching nucleus | ¹³⁹La · 57 protons + 82 neutrons | Reference isotope used in the nucleus model | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Page evidence note | Atomic identity and reference values are source-reviewed. Material viewers are teaching representations, not crystallographic refinements. Search demand shapes headings and FAQs but never overrides measured/evaluated evidence or element-versus-compound distinctions. | Evidence summary for this guide | Reviewed |
| Structure evidence | Lanthanum is commonly described by a DHCP ordinary-temperature structure. Temperature-dependent allotropy exists; this viewer shows only the ordinary structural reference rather than pretending one lattice persists to melting. | Measured structure, labelled schematic, prediction or explicit unknown as applicable. | Reviewed |
| Map evidence rule | Real pins are reviewed examples; conceptual layers are used when pins would mislead. | Geography Explorer 2.0 | Reviewed |
| Source set | 3 primary/reference links listed below | Open the Sources section for the actual references. | Reviewed |
Is Lanthanum a solid, liquid or gas? State at temperature
At approximately standard pressure, lanthanum is treated as a solid below 1193 K, liquid between melting and approximately 3737 K, and gas above the boiling reference. The ordinary crystal label applies to the stated material reference; unmodeled solid allotropy is not fabricated.
Where on Earth is Lanthanum found or produced?
Who discovered Lanthanum, and when?
Carl Gustaf Mosander separated a new oxide from ceria and named the new element lanthanum.
Lanthanum was recognized as one member of a family of chemically similar rare-earth elements.
Optical glass, catalyst and alloy applications expanded as rare-earth separation improved.
Lanthanum is used mainly through compounds and alloys rather than as bulk elemental metal.
From source material to Lanthanum applications: high-level material path
Lanthanum is obtained from mineral or metallurgical feedstocks in which it is chemically associated with other elements rather than mined as abundant native metal.
Industrial separation and refining produce element-specific compounds or metal feedstock; this guide does not provide operational extraction recipes.
The refined material is converted into the particular alloy, compound, doped host or component required by the application.
Recycling and recovery depend on the host product, concentration and economics; application materials must not be confused with pure element.
What is lanthanum used for?
Optical glass
La-containing glasses are used where optical properties such as refractive index are important.
NiMH batteries
Lanthanum-rich rare-earth alloys can form hydrogen-storage electrode materials.
Catalysts
Lanthanum compounds modify selected refining and emissions-control catalysts.
Specialty alloys
Lanthanum-containing alloys and mischmetal support niche metallurgical and ignition applications.
Lanthanum isotopes and natural abundance
¹³⁹La
Dominant natural isotopeStable and overwhelmingly abundant in natural lanthanum.
¹³⁸La
Trace natural radioisotopeVery long-lived and naturally occurring.
Natural lanthanum
Two-isotope natural mixtureThe relative atomic mass is abundance-weighted.
Five-question Lanthanum check
What is Lanthanum’s atomic number?
Which classification best fits Lanthanum?
What is the representative teaching isotope?
Which statement respects the material evidence?
Which rule should guide real-world uses?
Lanthanum questions students commonly ask
Each answer starts with the direct fact, then explains the chemistry, evidence or material context so the result is understandable rather than merely memorized.
What is lanthanum?
Short answer: Lanthanum is chemical element 57, a soft silvery rare-earth metal at the start of the lanthanide series.
Atomic number 57 means every lanthanum nucleus contains 57 protons. In the periodic table, Lanthanum is classified here as a lanthanide / rare-earth metal in Period 6 and Group Lanthanide. Lanthanum begins the lanthanide series in Period 6. Its [Xe] 5d¹6s² ground state readily gives La³⁺, leaving a xenon-like ion and chemistry dominated by the +3 state.
Key point: La is element 57; its periodic position and electron structure explain the rest of the page.
What is lanthanum used for?
Short answer: Lanthanum compounds and alloys are used in optical glass, catalysts, nickel-metal-hydride batteries and hydrogen-storage materials.
Optical glass: La-containing glasses are used where optical properties such as refractive index are important. NiMH batteries: Lanthanum-rich rare-earth alloys can form hydrogen-storage electrode materials. Lanthanum metal, La³⁺ ions and lanthanum-containing glass, catalysts or battery alloys are different material contexts. “Rare earth” describes a chemical family and supply context, not a claim that the metal is literally rare everywhere.
Key point: Always distinguish the pure element from the compound, alloy, isotope or device material that actually performs the application.
Where is lanthanum found?
Short answer: It occurs mixed with other rare-earth elements in minerals such as bastnäsite and monazite and is separated during rare-earth processing.
Lanthanum is obtained from mineral or metallurgical feedstocks in which it is chemically associated with other elements rather than mined as abundant native metal. Lanthanum metal, La³⁺ ions and lanthanum-containing glass, catalysts or battery alloys are different material contexts. “Rare earth” describes a chemical family and supply context, not a claim that the metal is literally rare everywhere.
Key point: Natural occurrence, resources, production and recycling are different geography questions.
Is lanthanum a metal?
Short answer: Yes. It is a reactive rare-earth metal.
This guide classifies Lanthanum as a lanthanide / rare-earth metal. Its periodic position is Period 6, d-block, Group Lanthanide. Lanthanum begins the lanthanide series in Period 6. Its [Xe] 5d¹6s² ground state readily gives La³⁺, leaving a xenon-like ion and chemistry dominated by the +3 state.
Key point: Periodic-table classification describes recurring atomic/chemical behavior; it does not make every element in a column physically identical.
Is lanthanum a transition metal?
Short answer: Lanthanum has a 5d electron and is sometimes discussed at the d-block/lanthanide boundary, but it is conventionally treated as the first lanthanide in this guide.
This guide classifies Lanthanum as a lanthanide / rare-earth metal. Its periodic position is Period 6, d-block, Group Lanthanide. Lanthanum begins the lanthanide series in Period 6. Its [Xe] 5d¹6s² ground state readily gives La³⁺, leaving a xenon-like ion and chemistry dominated by the +3 state.
Key point: Periodic-table classification describes recurring atomic/chemical behavior; it does not make every element in a column physically identical.
Who discovered lanthanum?
Short answer: Carl Gustaf Mosander discovered lanthanum in 1839 while separating rare-earth oxides.
In 1839, Carl Gustaf Mosander separated a new oxide from ceria and named the new element lanthanum. In the 19th century, Lanthanum was recognized as one member of a family of chemically similar rare-earth elements.
Key point: Discovery credit follows the historical evidence and accepted attribution, not just the earliest claim.
How many valence electrons does lanthanum have?
Short answer: Its ground state is [Xe] 5d¹ 6s²; loss of those three outer electrons gives the common La³⁺ ion.
The neutral-atom ground-state reference used on this page is [Xe] 5d¹ 6s². This is an isolated-atom reference: bonding and ion formation can change which outer electrons are present or chemically active. The listed common oxidation-state context is +3, which helps connect the atomic configuration to ordinary chemistry without treating electron counting as a single universal rule.
Key point: Electron configuration is a ground-state atomic reference, not a literal picture of every compound.
What group is lanthanum in?
Short answer: It is placed with the lanthanides in Period 6; group-number conventions around La/Lu vary across periodic-table layouts.
This guide classifies Lanthanum as a lanthanide / rare-earth metal. Its periodic position is Period 6, d-block, Group Lanthanide. Lanthanum begins the lanthanide series in Period 6. Its [Xe] 5d¹6s² ground state readily gives La³⁺, leaving a xenon-like ion and chemistry dominated by the +3 state.
Key point: Periodic-table classification describes recurring atomic/chemical behavior; it does not make every element in a column physically identical.
Scientific sources for Lanthanum
- Royal Society of Chemistry - Lanthanum
- NIST - Atomic Weights and Isotopic Compositions
- IUPAC - Periodic Table of Elements
Questions to ask next about Lanthanum
A good element lesson should lead to the next useful question, not end after a list of facts.
Found an error, something unclear, or a missing topic?
Tell us what you noticed. Feedback goes to a private review queue and is never published automatically.