Arrange The Following Elements In Order Of Decreasing First Ionization Energy: S, Ca, F, Rb, And Si.
Rank From Largest To Smallest. To Rank Items As Equivalent, Overlap Them.
The Correct Answer and Explanation is :
To arrange the elements in order of decreasing first ionization energy, we need to consider the periodic trends of ionization energy. Ionization energy refers to the amount of energy required to remove an electron from an atom in its gaseous state. The factors influencing ionization energy include atomic size and the effective nuclear charge (Z_eff).
Key Trends:
- Ionization energy increases across a period (left to right): As you move across a period, the nuclear charge increases while the number of electron shells remains constant. This results in a stronger attraction between the nucleus and the electrons, making it harder to remove an electron.
- Ionization energy decreases down a group (top to bottom): As you move down a group, the number of electron shells increases, which means the outer electrons are farther from the nucleus and experience more shielding. This makes it easier to remove an electron.
Now, let’s examine the elements:
- Fluorine (F): Fluorine is a halogen in Group 17 and Period 2. It has a high effective nuclear charge, and its small size means its electrons are tightly held. This gives it the highest ionization energy of the group.
- Sulfur (S): Sulfur is in Group 16 and Period 3. It has a lower ionization energy than fluorine because it is larger and has more shielding.
- Silicon (Si): Silicon is in Group 14 and Period 3. It has a lower ionization energy than sulfur due to being further left on the periodic table.
- Calcium (Ca): Calcium is in Group 2 and Period 4. It has a low ionization energy because it is an alkaline earth metal, and its outer electron is relatively far from the nucleus.
- Rubidium (Rb): Rubidium is in Group 1 and Period 5. It has the lowest ionization energy because it is a Group 1 alkali metal, and its outermost electron is very far from the nucleus with significant shielding.
Order of Decreasing Ionization Energy:
- Fluorine (F) – Highest ionization energy.
- Sulfur (S) – Next highest, but lower than fluorine.
- Silicon (Si) – Lower than sulfur due to its position in the periodic table.
- Calcium (Ca) – Lower still due to its group and period.
- Rubidium (Rb) – Lowest ionization energy due to its group and position.
Final Ranking:
F > S > Si > Ca > Rb