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. [1 Mark]
• 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. [1 Mark]
• This causes increase in force of attraction of nucleus resulting in decrease of atomic size. [1 Mark]