# (solved)Question 3.24 of NCERT Class XI Chemistry Chapter 3

Describe the theory associated with the radius of an atom as it (a) gains an electron (b) loses an electron
(Rev. 19-Dec-2022)

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### Question 3.24NCERT Class XI Chemistry

Describe the theory associated with the radius of an atom as it (a) gains an electron (b) loses an electron

### Solution in Detail(video solution below this)

$\displaystyle \underline{\underline{\text{Part (a)}}}$

The newly added electron is added to the valence shell and anion is formed.

Mutual repulsion between the electrons of the valence shell increases, which causes the size to increase.

Effective nuclear charge decreases because of the increased mutual shielding, which causes the size to increase.

Addition of a new electron may cause it be added to a new principal shell - leading to a significant increase in size.

Examples: F atom is 40 pico-m and F- is 130 pico-m.

$\displaystyle \underline{\underline{\text{Part (b)}}}$

The newly removed electron leads to a cation.

Mutual repulsion decreases between the electrons of the valence shell, leading to a decrease in size.

Effective nuclear charge increases because of less mutual shielding, which causes the size to decrease.

Addition of a new electron may cause it be removed from a principal shell - leading to a significant decrease in size.

Examples: Li atom is 165 pico-m and Li+ is 75 pico-m.

### Video Explanation

Please watch this youtube video for a quick explanation of the solution: