Explain the following.
The atomic radii of Cl, I, and Br are 99, 133, and 114 pm, respectively.
- Cl, I and Br belong to group 17 (halogen group) in the periodic table.
- As we move down the group from top to bottom in the periodic table, a new shell gets added to the atom of the elements.
- As a result, the effective nuclear charge decreases due to an increase in the atomic size as well as an increased shielding effect.
- Therefore, the valence electrons experience less attractive force from the nucleus and are held less tightly resulting in the increased atomic radius.
- Thus, their atomic radii increase in the following order down the group.
Cl (99 pm) < Br (114 pm) < I (133 pm)
Hence, the atomic radii of Cl, I, and Br are 99, 133, and 114 pm, respectively.
Concept: Periodic Trends in Elemental Properties
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