Question

4. Find reason for the following

a) Size of atom decreases from left to right across a period.

b) Size of atom increases from top to bottom in a group​

Answer 1

Explanation:

a) The atomic radius of atoms generally decreases from left to right across a period. There are some small exceptions, such as the oxygen radius being slightly greater than the nitrogen radius. Within a period, protons are added to the nucleus as electrons are being added to the same principal energy level.

b) The atomic radius of atoms generally increases from top to bottom within a group. As the atomic number increases down a group, there is again an increase in the positive nuclear charge. However, there is also an increase in the number of occupied principle energy levels.

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