Question

How does the atomic radius change in a period and a group?

Answer 1

In groups the atomic radius is increases from top to bottom and in periods it is decreasing from left to right.

Answer 2

Atomic radius of the elements generally decreases from left to the right in a period because on moving from left to right in aperiod the nuclear charge gradually increases by one unit & one electron is also added in the electron shell.Due to  this the electrons get attracted more & more towards the nucleus.consequently the atomic radii decreases .

Atomic radius of the elements increases as we move downwords in a group because on moving down a group there is an increase in principal quantum number & thus, increase in the number of electrons shells.Therefore the atomic size is expected to increase

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