Question

The atomic size of an element is ---------

• A. Directly proportional to the nuclear charge
• B. Directly proportional to the number of valence electrons
• C. Inversely proportional to the number of core electrons
• D. Inversely proportional to the effective nuclear charge

Answer 1

The correct option is D

Inversely proportional to the effective nuclear charge

Explanation for the correct option: (d)

1. The size of atoms generally decreases with an increase in the effective nuclear charge.
2. The increase in the effective nuclear charge causes the nucleus to attract the outer electron cloud with a greater force. Hence this decreases the atomic size.

Explanation for incorrect options:

a) The atomic size of an element is not directly proportional to the nuclear charge. It is inversely proportional to the nuclear charge.

b) The atomic size of an element is not directly proportional to the number of valence electrons.

c) The atomic size of an element is inversely proportional to the effective nuclear charge not to the number of core electrons.

Hence option (d) is correct and the atomic size of an element is inversely proportional to the effective nuclear charge.