Atomic numbers of Actinoides are from _____.

Question

Question

This question was previously asked in

RRC Group D Previous Paper 35 (Held On: 8 Oct 2018 Shift 2)

Answer 1

The correct answer is option 3, i.e., 89-103.

Atomic numbers of Actinoides are from 89-103.
Actinides start from Actinium and go till the Lawrencium, i.e., there are 15 elements.
Actinium (atomic no. 89) is often included in group 3, and the f-block actinides start from Thorium (atomic no. 90) thus reducing the elements to 14.
The term Actinide means "actinium-like" and the elements included are: Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, and Lr.
Actinides have variable valency, very large atomic and ionic radii, and exhibit an unusually large range of physical properties.
All actinides are radioactive in nature, Uranium, and Thorium being the naturally occurring radioactive elements.
58-71 atomic numbers belong to the first series of the f-block i.e., the lanthanides.
Lanthanides start from Lanthanum and the last lanthanide is Lutetium.
But, similar to Actinium, Lanthanum (atomic no. 57) is not included in the f-block and belongs to the group 3.
Hence, the f-block lanthanides are from atomic number 58-71.
The Lanthanide series include: Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.