Question

What is atomic size? why atomic size increases in groups but decrease in periods

Answer 1

Answer:

Reason: moving from left to right across a period, electrons are added one at a time to the outer energy shell. Electrons within a shell cannot shield each other from the attraction to protons, while moving down a group in the periodic table, the number of electrons and filled electrons shells increases.

Answer 2

Answer:

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Explanation

Reason: moving from left to right across a period, electrons are added one at a time to the outer energy shell. Electrons within a shell cannot shield each other from the attraction to protons, while moving down a group in the periodic table, the number of electrons and filled electrons shells increases.