Rank the following elements according to their ionization energy: 1. Aluminum 2. Oxygen 3. Fluorine 4. Sulfur
The Correct Answer and Explanation is:
The ionization energy of an element refers to the amount of energy required to remove an electron from the outermost shell of an atom in its gaseous state. Ionization energy typically increases across a period (left to right) and decreases down a group (top to bottom) in the periodic table.
To rank the given elements—Aluminum (Al), Oxygen (O), Fluorine (F), and Sulfur (S)—according to their ionization energy, we should consider their positions in the periodic table:
- Fluorine (F): Fluorine is in Group 17 (the halogens) and Period 2. Halogens have high ionization energies because they have a strong tendency to gain an electron to complete their valence shell, making them very electronegative. Fluorine has the highest ionization energy among the elements listed.
- Oxygen (O): Oxygen is in Group 16 and Period 2. While oxygen has a relatively high ionization energy, it is less than that of fluorine because it is one group to the left on the periodic table. This means oxygen has a lower nuclear charge than fluorine, leading to a weaker attraction for its outermost electrons, so it requires less energy to ionize.
- Sulfur (S): Sulfur is in Group 16, Period 3. Moving down a group, ionization energy decreases as the outer electrons are farther from the nucleus and experience more shielding. Hence, sulfur has a lower ionization energy compared to oxygen.
- Aluminum (Al): Aluminum is in Group 13 and Period 3. It is the farthest to the left on the periodic table, and as a result, it has the lowest ionization energy among the elements listed. Elements in Group 13 have relatively low ionization energies because they have fewer protons to attract the outermost electron compared to elements in groups 16 and 17.
Ranking by Ionization Energy (highest to lowest):
- Fluorine (F)
- Oxygen (O)
- Sulfur (S)
- Aluminum (Al)
This ranking follows the general trend in the periodic table where ionization energy increases across a period and decreases down a group.
