Question

which of the following atom has the lowest ionization potential? (A) \({ }^{14}{ }_{7} \mathrm{~N}\) (B) \({ }^{40}{ }_{18} \mathrm{Ar}\) (C) \({ }^{133} 55 \mathrm{Cs}\) (D) \({ }^{16}{ }_{8} \mathrm{O}\)

Short answer

The atom with the lowest ionization potential is (C) \({ }^{133} 55 \mathrm{Cs}\) (Cesium), as it is farther down and to the left in the periodic table compared to the other options.

Step-by-step solution

Identify each atom's position on the periodic table

To analyze the ionization potential, first, we need to determine the position of each atom in the periodic table. The atomic number (number of protons) will help in identifying the element, and the period and group they belong to. (A) \({ }^{14}{ }_{7} \mathrm{~N}\) : Nitrogen, Period 2, Group 15 (5A) (B) \({ }^{40}{ }_{18} \mathrm{Ar}\) : Argon, Period 3, Group 18 (8A) (C) \({ }^{133} 55 \mathrm{Cs}\) : Cesium, Period 6, Group 1 (1A) (D) \({ }^{16}{ }_{8} \mathrm{O}\) : Oxygen, Period 2, Group 16 (6A)

Compare the atoms' ionization potentials based on their position in the periodic table

As mentioned before, ionization potential decreases down a group and increases across a period. We can now compare the atoms according to their position: - Nitrogen and Oxygen are in the same period (Period 2), but Oxygen has a higher ionization potential because it is farther to the right. - Argon is in a higher period (Period 3) than Nitrogen and Oxygen and is in Group 18, which is the farthest right group on the periodic table, thus having a very high ionization potential. - Cesium is in Period 6 and Group 1. It is farther down and to the left on the periodic table, indicating lower ionization potential compared to the other atoms.

Determine which atom has the lowest ionization potential

Based on the positions of each atom on the periodic table, we can conclude that Cesium (\({ }^{133} 55 \mathrm{Cs}\)) has the lowest ionization potential among the given options. Thus, the correct answer is (C) \({ }^{133} 55 \mathrm{Cs}\).