The size of an atom depends on the position of the element in the periodic table. Which of these elements has the greatest atomic radius?

A) Cl

B) Na

C) P

D) Si

Sodium

Explanation:

The given elements are present in period three.

As we move from left to right across the periodic table the number of valance electrons in an atom increase. The atomic size tend to decrease in same period of periodic table because the electrons are added with in the same shell. When the electron are added, at the same time protons are also added in the nucleus. The positive charge is going to increase and this charge is greater in effect than the charge of electrons. This effect lead to the greater nuclear attraction. The electrons are pull towards the nucleus and valance shell get closer to the nucleus. As a result of this greater nuclear attraction atomic radius decreases and ionization energy increases because it is very difficult to remove the electron from atom and more energy is required.

Sodium is present at the start of period three so its atomic radius is greater while the smallest atomic radius will be of chlorine.