Why is there an ionic radius trend?

Jun 21, 2018

We know that atomic size is a function of (i) atomic number $Z$, and (ii) shielding by other electrons. And incomplete electron shells tend to shield the nuclear charge VERY imperfectly. This has the result that atomic SIZE decreases across the Period, from left to right as we face the Table, and INCREASES down the Group.
Do these data support what I have argued? Units are in $\text{picometres}$, $1 \cdot \text{pm} = 1 \times {10}^{-} 12 \cdot m$.