Chapter 17, Problem 2TC

To determine

The rank of the elements cesium, silver and oxygen in order of the size of the atoms from smallest to largest.

Answer to Problem 2TC

The ranking of the elements cesium (Cs) with atomic number $\text{55}$, silver (Ag) with atomic number $47$ and oxygen (O) with atomic number $8$, in order of the size of the atoms from smallest to largest is:

$\text{O <Ag < Cs}$

Explanation of Solution

In general, across a period from left to right, the atomic size decreases due to the increased effective nuclear charge and within a group from top to bottom the atomic size increases due to the successive addition of energy shells.

As cesium with atomic number $\text{55}$ is present in group $\text{1A}$ in the periodic table, silver with atomic number $47$ is present in middle as transition element and oxygen with atomic number $8$ is present to the right of the periodic table. So the ranking of the elements in order from smallest to largest is:

$\text{O <Ag < Cs}$

Conclusion:

Therefore the order is:

$\text{O <Ag < Cs}$