Question

Arrange the following sets of elements in order of increasing atomic size. a. \(\mathrm{Sn}, \mathrm{Xe}, \mathrm{Rb}, \mathrm{Sr}\) b. \(\mathrm{Rn}, \mathrm{He}, \mathrm{Xe}, \mathrm{Kr}\) c. \(\mathrm{Pb}, \mathrm{Ba}, \mathrm{Cs}, \mathrm{At}\)

Short answer

a. Xe < Sn < Sr < Rb b. He < Kr < Xe < Rn c. At < Pb < Ba < Cs

Step-by-step solution

a. Arrange Sn, Xe, Rb, and Sr in order of increasing atomic size

First, locate these elements in the periodic table: - Sn (Tin) is in Group 14, Period 5 - Xe (Xenon) is in Group 18, Period 5 - Rb (Rubidium) is in Group 1, Period 5 - Sr (Strontium) is in Group 2, Period 5 The atomic size increases as we move from right to left in a period (due to increased shielding) and increases as we move down a group (due to additional energy levels). Since all are in the same period, we focus on the group position. The order of increasing atomic size: Xe < Sn < Sr < Rb

b. Arrange Rn, He, Xe, and Kr in order of increasing atomic size

First, locate these elements in the periodic table: - Rn (Radon) is in Group 18, Period 6 - He (Helium) is in Group 18, Period 1 - Xe (Xenon) is in Group 18, Period 5 - Kr (Krypton) is in Group 18, Period 4 Since all are in the same group, we focus on the period position. The order of increasing atomic size: He < Kr < Xe < Rn

c. Arrange Pb, Ba, Cs, and At in order of increasing atomic size

First, locate these elements in the periodic table: - Pb (Lead) is in Group 14, Period 6 - Ba (Barium) is in Group 2, Period 6 - Cs (Cesium) is in Group 1, Period 6 - At (Astatine) is in Group 17, Period 6 Since all are in the same period, we focus on the group position. The order of increasing atomic size: At < Pb < Ba < Cs