Question

How does atomic size verify across the period and down the group

Answer 1

I guess the question should be like this : How does the atomic size varies across the period and down the group?

Ans: Atomic size of an atom of an element is determined by its atomic radius. And atomic radius goes on increasing as we go from left to right in a period because one electron is added to its outermost shell . This makes the force of attraction between nucleus and the outermost shell less and atomic size goes on increasing.In the group as we move from top to bottom one shell is added to atom and this increases the force of attraction leading to decrease in atomic size.
        Therefore, atomic size increases in a period and decreases in a group.