Lanthanum

Lanthanum is a chemical element with the symbol La and atomic number 57. Lanthanum serves as the namesake and prototype for the lanthanide series, a group of 15 chemically similar elements that range from lanthanum to lutetium in the modern periodic table. Being the first element in this series, lanthanum is a key reference point for the properties of the other lanthanides.

1.0Introduction 

Lanthanum (La) is a silvery-white, ductile metal with an atomic number of 57. It slowly tarnishes in the air and is the first element in the lanthanide series, which includes 15 similar elements from lanthanum to lutetium.

Traditionally classified as a rare earth metal, lanthanum primarily exhibits a +3 oxidation state. While it has no known biological role in humans, it is important to some bacteria 

and shows antimicrobial activity without being toxic to humans.

Position in the Periodic Table

• Lanthanum is the first element in the lanthanide series, located in the f-block of the periodic table. However, it is a d-block element itself.
• The 14 elements that follow lanthanum are known as the lanthanides, and they share similar chemical and physical properties with lanthanum.
• While traditionally placed in Group 3, lanthanides are increasingly considered as not belonging to any specific group.

Discovery of Lanthanum

• Discovered by: Carl Gustaf Mosander, a Swedish chemist, in 1839.
• Source: Lanthanum was isolated from the mineral cerite.
• Name Origin: The name "lanthanum" comes from the Greek word "lanthanein," meaning "hidden," due to its challenging separation from cerite.
• In 1923, Kremers and Stevens obtained pure lanthanum by electrolyzing fused lanthanum halides.

2.0Physical properties of Lanthanum 

3.0Chemical Reactions of Lanthanum

• Reaction with Water: Lanthanum reacts gradually with cold water and rapidly with hot water, producing lanthanum hydroxide and hydrogen gas:

2La(s)+6H₂O(g)→2La(OH)³(aq)+3H₂(g)

• Reaction with Air: When burned in air, lanthanum forms lanthanum(III) oxide:4La(s)+3O₂(g)→2La₂O₃(s)
• Reaction with Dilute Sulfuric Acid: Lanthanum readily dissolves in dilute sulfuric acid, yielding aquated La(III) ions and hydrogen gas:

2La(s)+3H₂SO₄(aq)→2La₃+(aq)+3SO₄²⁻(aq)+3H₂(g)

• Reaction with Halogens: Lanthanum is highly reactive with halogens, producing various lanthanum halides:

2La(s)+F₂(g)→2LaF₃(s)

2La(s)+Cl₂(g)→2LaCl₃(s)

4.0Uses of Lanthanum

• High-Refraction Glasses: Pure lanthanum is used in manufacturing high-refraction optical glasses.
• Hydrogen Storage and Batteries: It is crucial for hydrogen storage alloys and rechargeable nickel-metal hydride (NiMH) batteries.
• Alloying Agent: Lanthanum is used in alloys to remove impurities like oxygen and sulfur.
• Fluorescent Lighting: It is a key component in fluorescent lighting.
• Water Treatment: Used to eliminate phosphates in pools, preventing algae growth.
• Steel Alloys: Enhances plasticity and corrosion resistance in steel alloys.