Question

(1)-How does valency vary in a group on going from top to bottom? (2)- How does atomic size vary in a period group on going from left to right?

Answer 1

1) valency reamin same
2) atomic size decreases from left to right in period

Answer 2

Explanation:

On moving from top to bottom in a group, there is no change in the valency as there is no change in bonding behavior of core electrons. Hence, the valency does not get affected.

Whereas atomic size decreases when we move across a period because the addition of electrons occur in the same shell. As a result, there will be increase in nuclear charge by the nucleus hence, electrons are pulled closer to the nucleus.

On the other hand, when we move down the group, there will be increase in size of atom as the number of shells and electrons increases. Each shell is far away from the nucleus as a result, there will be less attraction between the nucleus and outermost electrons. Therefore, there will be no decrease in size.