Lanthanides elements start from atomic number

The lanthanide series, which ranges in atomic number from 58 to 71, begins with cerium and concludes with lutetium.

The lanthanides are a group of 15 metallic elements, also known as rare-earth elements, that form a part of the periodic table. They are placed in the 6th period and are characterized by their similar chemical and physical properties.

Atomic Number Range

The lanthanides begin with cerium (Ce), which has an atomic number of 58, and end with lutetium (Lu), which has an atomic number of 71. Therefore, the range of atomic numbers for lanthanides is 58 to 71.

Why Not Other Options?

• Option A (56 to 69): The element with atomic number 56 is barium, which belongs to the alkali earth metals, not lanthanides.
• Option B (57 to 70): While lanthanum (57) is often considered a part of lanthanides for convenience, the actual series begins with cerium (58).
• Option D (59 to 72): This range includes some transition metals like hafnium (72), which does not belong to the lanthanides.

Unique Characteristics of Lanthanides

• They have partially filled 4f orbitals, which give them unique magnetic and optical properties.
• Lanthanides are known for their high reactivity and ability to form alloys.

Thus, the correct answer is Option C (58 to 71), as it correctly specifies the atomic number range of the lanthanide series.