Question

An element Barium has atomic number 56. Look up its position in the periodic table and answer the following questions.
(v) Is it larger or smaller than caesium (Cs) in size?

Answer 1

• Caesium (55) and Barium (56) are present in the same period i.e period 6
• Caesium belongs to group 1 whereas barium belongs to group 2.
• Thus, Caesium is present at the left side of the barium in the same period of the periodic table.
• Across a period, the nuclear pull increases and the atomic size decreases.

Thus, barium (Ba) is smaller than caesium (Cs) in size.