How does the atomic size vary on going down from top to bottom in a group of the periodic table? Why does it vary this way? (b) Lithium, sodium and potassium are all metals that react with water to liberate hydrogen gas. Is there any similarity in the atoms of these elements? Explain your answer.
ChemistryClass 10ICSEAnswered 27 Mar 2026
Answer
(a) Atomic size increases on going down in a group of the periodic table and when moving top to bottom shell is added at each step due to the size of the atom increases.
(b) Yes, the atoms of all the three elements lithium, sodium and potassium have one electron in their outermost shells.