Question

How does the atomic size vary in group and across a period?

Answer 1

Explanation:

Atomic size decrease across a period from left to right we face the table, but increase down a group,A column of the period table. ... and 5hus across periodic nuclear charge predominates, and draw the valance electron towards the nuclear core, with the result of a marked decrease.

please mark me as brainliest answer

Answer 2

Answer:

(1) In a period : Atomic radius decreases in a period from left to right (upto group 17). This is because as we move across a period, nuclearncharge increases but electrons enter the same shell. Thus, the screening effect of the inner core remains the same. As a result the valence electrons are tightly held by the nucleus and atomic size (radius) decreases. For example, in 2nd Period, it decreases from Li(152 pm) to F(64 pm).

(2) In a group : Down the group, as the atomic number increase, nuclear charge increses but number of shells increase. As a result, shielding effect increases and valence electrons are held by weaker attrctive forces. Thus, atomic radius increases. For example, atomic radius increases. For group 17 elements, the value increase from 1st member F (64 pm) to the last member At (140 pm).