Question

On going down a group, the size of an atom increases because:

• A. A new orbit is added on going down in a group.
• B. The distance between the nucleus and the outermost orbit remains the same.
• C. The charges in the nucleus remain constant.
• D. None of the above.

Hint:

As we move down a group, the number of electron shells increases, leading to a larger atomic radius.

Answer 1

The Correct Option is A

As we move down a group in the periodic table, the number of electron shells (or orbits) increases. This leads to an increase in the size of the atom because the outermost electrons are farther away from the nucleus.
- Option (A) is correct because when moving down a group, a new electron shell is added, increasing the atomic size.
- Option (B) is incorrect because the distance between the nucleus and the outermost electron actually increases as new shells are added.
- Option (C) is incorrect because although the nuclear charge increases, the effect is counteracted by the addition of more electron shells, leading to increased shielding and a larger atomic size.
- Option (D) is incorrect because option (A) provides the correct explanation.
Thus, the correct answer is (A).