CBSE Class 11-science Answered

Atomic radius depends on the following factors:

• Number of filled shells: The atomic radius increases with increase in the number of filled shells. This is because, the distance between the outermost filled shell and the nucleus increases. Therefore the outermost valence electrons are far away from nucleus so less attracted by it. These loosely held electrons result into increase in the atomic radius.
•  Nuclear charge: The atomic radius decreases with increase in nuclear charge as larger nuclear charge holds the electrons closer to nucleus.
• Screening effect: Increase in the number of filled inner shells result into increase in the screening effect. These inner filled shells screen the valence electrons from the nuclear attraction. This result into increase in atomic radius.