Rank the following elements according to their ionization energy. Element Ionization Energy Lead (Choose one) (highest) 2 Iodine (lowest) (choose one) Tellurium Polonium (Choose one)
Here is the correct ranking for the elements based on their ionization energy:
- Lead: 4 (lowest)
- Iodine: 1 (highest)
- Tellurium: 2
- Polonium: 3
Explanation
Ionization energy is the amount of energy required to remove the outermost electron from a neutral atom in its gaseous state. The magnitude of this energy is determined by two primary periodic trends which relate to an element’s position on the periodic table.
First, ionization energy generally increases as you move from left to right across a period. This happens because the number of protons in the nucleus increases within the same energy shell. The resulting higher effective nuclear charge pulls the electrons more tightly, making them more difficult and energy intensive to remove.
Second, ionization energy generally decreases as you move down a group. As you descend a group, atoms gain additional electron shells. The outermost, or valence, electron is consequently farther from the nucleus and is shielded from the nucleus’s positive charge by the inner electrons. This increased distance and shielding effect weaken the attraction between the nucleus and the valence electron, so less energy is needed to remove it.
To rank the given elements, we locate them on the periodic table. Iodine (I) and Tellurium (Te) are in Period 5, while Polonium (Po) and Lead (Pb) are in Period 6.
- Iodine (I) has the highest ionization energy. It is in Period 5 and Group 17, placing it the furthest to the right and highest up among the four elements. It has a high effective nuclear charge for its period and fewer electron shells than the Period 6 elements.
- Tellurium (Te) is second. It is in the same period as Iodine but one group to the left (Group 16). Its ionization energy is lower than Iodine’s but higher than the elements in the period below it.
- Polonium (Po) is third. It is directly below Tellurium in Group 16. Being in Period 6, it has an additional electron shell compared to Tellurium, which significantly lowers its ionization energy.
- Lead (Pb) has the lowest ionization energy. It is in the same period as Polonium (Period 6) but is further to the left (Group 14). This position means it has both the effect of being in a lower period and having a lower effective nuclear charge than Polonium, giving it the weakest hold on its valence electron.
Therefore, the final ranking from highest to lowest ionization energy is Iodine > Tellurium > Polonium > Lead.
