Question

Define atomic radius .How does it vary in a group in a period.

Answer 1

Explanation:

atomic radius is the distance between the nucleus of an atom and the outermost orbit

in a group while going from top to bottom atomic size goes on increasing this is because while going down new cells get added therefore the distance between the outermost orbit and nucleus goes on increasing

but in period while going from left to right the outermost orbit remains same but electron get added in valence shell therefore the electrons are pulled towards the nucleus to an greater extent and atomic radius decreases

Answer 2

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In general, the atomic radius decreases as we move from left to right in a period with an increase in nuclear charge of the element. The atomic radius increases when we go down a group because of the addition of extra shell.