Question

Why is there a steady increase in atomic radius on moving from top to bottom in a group?

Answer 1

Atomic radius determines the size of an atom.

• For an isolated atom, the atomic radius may be taken as the distance between the center of the nucleus of an atom and the outermost shell of electrons.
• Practically, measurement of the size of an isolated atom is difficult; therefore, it is measured when an atom is in the company of another atom of the same element. It is defined as one-half the distance between the nuclei of two atoms when they are linked to each other by a single covalent bond.
• Atomic radius increases as we move from top to bottom in a group of the periodic table because a new shell of electrons is added to the atoms at every step.
• As the number of shells in atoms increases gradually, so does the size of the atoms increases. As the size of the atoms increases, so does the atomic radius of an atom increases.