How do rationalize atomic size on the basis of an element's position on the Periodic Table?

1 Answer
Dec 21, 2017

Answer:

Atomic size DECREASES across a Period....

Explanation:

Atomic size DECREASES across a Period, a row of the Periodic Table, from LEFT to RIGHT as we face the Table. It INCREASES down a Group.

This is one of the most important manifestations of atomic structure; i.e. the diminution in size across the Period. Atomic size is a function of (i) nuclear charge, thus higher #Z# SHOULD have smaller radius; and (ii) shielding by other electrons. Incomplete electronic shells shield the nuclear charge VERY imperfectly....

Taken together, these two principles rationalize the actual data...

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Especially, for the first few short Periods, do these data support what we have argued? And so for a given Period, which is the largest atom?