Electronic Configuration of Lanthanum
Lanthanum, denoted by La, is a chemical element and a rare earth metal present in the Group 3 of the modern periodic table. It is known to be the prototype of the lanthanide series of the elements of the periodic table.
Lanthanum is a malleable and ductile metal, which is silvery-white in colour. It is softer enough that it can be even easily cut through a knife. Lanthanum is known to be the second most reactive rare-earth metals, the first being europium. The lanthanum compound tends to oxidize in the presence of air when kept at a room temperature and forms La₂O₃. It tends to react slowly with water and dissolves faster in the dilute acids, with an exception being the hydrofluoric acid, HF. this is due to the formation of the protective layer of fluoride, LaF₃ on the metal surface.
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What is Lanthanum
Lanthanum is a type of a chemical element denoted by the symbol La. The atomic number of lanthanum is 57. It is ductile and soft silvery-white metal which slowly tarnishes when it is exposed to the air. Lanthanum acts as the eponym of the lanthanide series, which is a group of 15 elements similar to one another starting from lanthanum to lutetium in the modern periodic table. Lanthanum lies first in the group and is hence the prototype.
Lanthanum is regarded traditionally amongst the rare earth metals. It possesses an oxidation state of +3. The element does not show any biological role when it comes to humans, but it is important to a few bacterial species. It does not prove toxic to humans but possesses antimicrobial activity.
Chemical Properties of Lanthanum
Properties of Lanthanum
Lanthanum is found abundantly in the environment.
It is silvery-white in colour
Lanthanum is active, ductile and soft.
Lanthanum tends to oxidize when reacted with water and forms its respective hydroxide.
The lanthanum salts are not soluble in water.
Uses of Lanthanum
Chemical form of lanthanum has its usage in the modern energy-saving lamps, televisions, fluorescent lamps and tubes, etc.
Lanthanum is also used in optics in the form of radiation-absorbing glasses and lenses.
It also increases the malleability and the resistivity of the steel.
Lanthanum is used to polish glass and to produce catalysts.
It is also used in the petroleum refineries for catalysis.
Health-Related Facts of Lanthanum
The primary problem associated with the lanthanum element is its disposal by the industries. The industrial wastes get dumped directly into the water bodies, mainly from the petroleum industries.
It tends to cause severe damage to both plants and animals and nervous system disorders amongst us humans.
FAQs on Lanthanum
1. What is lanthanum and where is it located in the periodic table?
Lanthanum (symbol La) is a chemical element with atomic number 57. It is a soft, silvery-white, and ductile metal. In the periodic table, it is placed in Group 3 and Period 6. Although its final electron enters the d-orbital, its properties are so similar to the elements that follow it that it serves as the prototype for the lanthanide series (f-block).
2. What are the most important uses of lanthanum and its alloys?
Lanthanum's primary importance comes from its use in alloys and compounds. Key applications include:
- Batteries: Lanthanum-nickel alloys are used for hydrogen storage in nickel-metal hydride (NiMH) batteries, commonly found in hybrid vehicles.
- Mischmetal: It is a major component (about 25%) of mischmetal, an alloy used to make flints for cigarette lighters.
- Catalysis: Lanthanum compounds are essential catalysts in petroleum refining for cracking long-chain hydrocarbons into more valuable products.
- Optics: Lanthanum oxide (La₂O₃) is added to glass to increase its refractive index, making it ideal for high-quality camera lenses and telescopes.
3. What are the key physical and chemical properties of lanthanum?
Lanthanum exhibits several distinct properties that define its character as a reactive metal:
- Physical Properties: It is a silvery-white metal that is soft enough to be cut with a knife. It is both malleable and ductile.
- Chemical Properties: Lanthanum is highly reactive. It rapidly oxidises in air to form a white layer of lanthanum oxide (La₂O₃). It reacts with water to form lanthanum hydroxide (La(OH)₃) and liberates hydrogen gas. Its most common and stable oxidation state is +3.
4. Why is lanthanum considered a member of the f-block (lanthanides) despite having no f-electrons?
Lanthanum is grouped with the f-block lanthanides primarily due to its overwhelmingly similar chemical properties. Its stable +3 ion (La³⁺) has an empty 4f subshell, which is the same stable configuration that other lanthanides achieve when forming their common +3 ions. Because its chemistry, ionic radius, and physical properties are so alike to the elements from Cerium (Ce) to Lutetium (Lu), it serves as the prototype for the entire series. This grouping maintains the logical flow of chemical behaviour in the periodic table.
5. Why is the electronic configuration of lanthanum, [Xe] 5d¹6s², a point of discussion?
The electronic configuration of lanthanum is debated because its final differentiating electron enters the 5d orbital, not the 4f orbital. According to the Aufbau principle, this technically makes it a d-block element. However, its chemical behaviour is nearly identical to the fourteen elements that follow it, where the 4f orbital is filled. This dual character—being a d-block element by structure but an f-block element by chemical kinship—is the source of the discussion.
6. How does lanthanum's stable +3 oxidation state explain its chemical behaviour?
Lanthanum's stable +3 oxidation state is the cornerstone of its chemistry. It achieves this state by losing its two 6s electrons and its single 5d electron, resulting in the highly stable electron configuration of the noble gas Xenon. The large energy required to remove a fourth electron makes the La³⁺ ion exceptionally stable. Consequently, lanthanum's chemistry is dominated by the formation of ionic compounds where it exists as this ion, such as in its oxide (La₂O₃) and halides (LaCl₃).
7. What is lanthanum carbonate and what is its primary medical application?
Lanthanum carbonate (La₂(CO₃)₃) is a salt of lanthanum that is used in medicine as a phosphate binder. In patients with chronic kidney disease, the kidneys cannot properly remove phosphate from the blood. Lanthanum carbonate is taken with meals to bind to dietary phosphate in the gut, forming an insoluble compound that is then excreted. This helps control high phosphate levels in the blood, a condition known as hyperphosphatemia.
