Question

Discuss the occurrence of the inner transition elements in nature. 

Answer 1

1. Inner transition elements consist of lanthanoids and actinoids, and belong to the f-block of the periodic table.
2. They are called inner transition elements because their differentiating electrons enter the (n − 2) f-subshell.
3. Lanthanoids range from atomic number 58 (Cerium) to 71 (Lutetium), while actinoids range from 90 (Thorium) to 103 (Lawrencium).
4. These elements are rare in nature and are often referred to as rare earth elements due to their scarcity in Earth’s crust.
5. Lanthanoids occur naturally mostly in minerals such as monazite and bastnäsite.
6. Actinoids, especially uranium and thorium, are found in nature, but many actinoids are synthetic and not naturally abundant.
7. Lanthanoids and actinoids have similar properties due to the filling of 4f and 5f orbitals, respectively.
8. Because of their rarity and similar chemical properties, they are difficult to separate from each other in nature.