Question

Write two similarities between chemistry of lanthanoids and actinoids.

Answer 1

Lanthanoids are the elements in which the differentiating electron enters (n-2) f-orbital, atomic numbers range from 57 to 71. Actinoids are a series of 15 consecutive elements from atomic numbers 89 to 103. Actinoids are present below the lanthanoids and these both are kept at the bottom of the periodic table.

Complete step by step solution:
We are given to write two similarities between chemistry of lanthanoids and actinoids.
Lanthanoids are the series of 15 consecutive metallic elements from lanthanum (57) to lutetium (71). These are widely used in making alloys to give strength and hardness to metals. Except lanthanum, all the other lanthanoids are f-block elements.
Actinoids are also a series of 15 consecutive metallic elements from actinium to lawrencium. These are very large because of their radioactive nature. Except actinium, all the other actinoids are f-block elements. Actinoids are present in the last row of the periodic table
Since f orbital is an inner penultimate shell, lanthanoids and actinoids are also called inner-transition elements.
Similarities:
Lanthanoids and actinoids are named after the first element in their respective series, lanthanum and actinium.
1. These both series elements mostly show an oxidation number +3 and elements are electropositive and very reactive.
2. Lanthanoids and actinoids show contractions in their radii and both show magnetic properties.

Note:
Lanthanoids are different from lanthanides and actinides are different from actinides. Do not confuse this. Lanthanides are Lanthanoids except lanthanide and actinides are actinoids except actinium. Lanthanides and actinides both have 14 elements not 15 elements, from Cerium (58) to Lutetium (71) and from Thorium (90) to Lawrencium (103).