Atomic radius increases down a group because the electrons feel a lesser attraction to the positive nucleus (due to shielding from inner shells). Why then, doesn't core charge decrease seeing as core charge is just the attraction felt by the valence electrons towards the nucleus (and that attraction is said to decrease down a group as per the reasoning for the increase in atomic radius)?

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    $\begingroup$ Technical note: Try to formulate shorter sentences. As a guidence for technical/scientific texts, it is adviced to write sentences with 20-25 words in average and discouraged writing sentences longer than 35 words. Your question has 66 words and is difficult to read and comprehend. Try to read your own question after several month. You may forget the beginning before you reach the end. Then you may need to read it again and again. $\endgroup$ – Poutnik May 27 '20 at 15:12
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    $\begingroup$ The felt attraction is proportional to $\frac{Z_\mathrm{eff}}{r^2}$. Ramember also electron repulsion and in the first place the quantization, which is the primary reason for atomic size getting bigger. $\endgroup$ – Poutnik May 27 '20 at 15:44