Lanthanum
Lanthanum is a chemical element with symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the first and prototype of the lanthanide series and is traditionally counted among the rare-earth elements.
- symbol
- La
- atomic_number
- 57
- discoverer
- Carl Gustaf Mosander
- classification
- Lanthanide, rare-earth element
- abundance_rank
- 28th most abundant element in Earth's crust
Lore & Background
Although classified as a rare-earth element, lanthanum is the 28th most abundant element in the Earth's crust, almost three times as abundant as lead. It usually occurs together with cerium and other rare-earth elements in minerals such as monazite and bastnäsite, where it composes about a quarter of the lanthanide content.
Reader's Guide
Lanthanum is significant as the prototype of the lanthanide series, a group of 15 similar elements. It has no biological role in humans but is used by some bacteria and shows antimicrobial activity. Its compounds have numerous applications, including catalysts, additives in glass, carbon arc lamps, ignition elements in lighters and torches, electron cathodes, scintillators, and gas tungsten arc welding electrodes. Lanthanum carbonate is used as a phosphate binder to treat high levels of phosphate in the blood accompanied by kidney failure. Lanthanum is the most reactive among the lanthanides, tarnishing rapidly in air and forming lanthanum(III) oxide. It has the largest atomic radius of the lanthanides and is the strongest and hardest base among the rare earth elements.
Did You Know?
- Lanthanum is the 28th most abundant element in the Earth's crust, almost three times as abundant as lead.
- Naturally occurring lanthanum consists of two isotopes: stable 139La and primordial long-lived radioisotope 138La.
- Lanthanum has no biological role in humans but is used by some bacteria.
- Lanthanum carbonate is used as a phosphate binder to treat high levels of phosphate in the blood accompanied by kidney failure.
Frequently Asked Questions
Who is Lanthanum?
Lanthanum (symbol La, atomic number 57) is a soft, ductile, silvery-white metal that sits at the very front of the lanthanide series. It is traditionally grouped with the rare-earth elements and serves as the template for the fourteen members that follow it.
What role does Lanthanum play in the lanthanide family?
As the prototype of the series, Lanthanum essentially sets the structural and chemical pattern that the rest of the rare-earth block inherits. Fans of the periodic table often treat it as the 'opening character' whose behavior foreshadows everything the later lanthanides will do.
Why is Lanthanum important in chemistry and materials science?
Because it marks the point where the 4f electron subshell begins to fill, Lanthanum anchors the entire lanthanide block and gives chemists a reference for understanding rare-earth behavior. Its position at atomic number 57 is what separates the transition metals from the f-block, making it a key boundary element.
How abundant is Lanthanum in Earth's crust?
Lanthanum ranks as the 28th most abundant element in the crust, so despite the 'rare-earth' label it is actually fairly common in total quantity. The challenge for materials scientists is that it rarely concentrates into easily mineable deposits, which is why extraction still requires processing large volumes of ore.
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