Question

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> How do atomic size vary in a period and in a group in p-block elements?How do you explain the variation?

Answer 1

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Within the group,the atomic sizeincreases down the group.This is because a new energy shell is added at each succeeding element while the number of electrons in the valence shell remains to be the same.
Therefore,the electrons added successively lie far away from the nucleus.The force of attraction of nucleus decreases in electrons,so the atomic size increases. In a period, the electrons are added to the same nucleus , so the nuclear charge increases with each successive element.
This causes increase in force of attraction of nucleus resulting in decrease of atomic size.