Let's analyze the ionization energies of each of the given atoms to determine which one has a greater ionization energy than phosphorus (P).
### Ionization Energy Trend in the Periodic Table
1. Trend Across a Period: Ionization energy generally increases from left to right across a period. This is because as you move across a period, the number of protons in the nucleus increases, which results in a stronger attraction between the nucleus and the electrons. This increased attraction makes it harder to remove an electron, thereby increasing the ionization energy.
2. Trend Down a Group: Ionization energy generally decreases as you move down a group. This is because as you move down a group, the number of electron shells increases, which places the outermost electrons further from the nucleus. This increased distance from the nucleus, and the added electron shielding from inner shells, lowers the attraction between the nucleus and the outermost electrons, making it easier to remove an electron and thus decreasing the ionization energy.
### Comparing the Ionization Energies
- Phosphorus (P): Phosphorus is in group 15 and period 3.
#### Option A: Barium (Ba)
- Barium is in group 2 and period 6.
- Ionization energy decreases significantly down a group and is also comparatively lower in group 2.
- Therefore, Barium has a much lower ionization energy than phosphorus.
#### Option B: Potassium (K)
- Potassium is in group 1 and period 4.
- It is to the left of phosphorus in the periodic table and also has more shells.
- Therefore, Potassium has a much lower ionization energy than phosphorus.
#### Option C: Arsenic (As)
- Arsenic is in group 15 and period 4, directly below phosphorus in the same group.
- Ionization energy decreases as you move down a group.
- Therefore, Arsenic has a lower ionization energy than phosphorus.
#### Option D: Chlorine (Cl)
- Chlorine is in group 17 and period 3.
- Chlorine is to the right of phosphorus in the periodic table.
- As you move from left to right across a period, the ionization energy increases.
- Therefore, Chlorine has a higher ionization energy than phosphorus.
### Conclusion
Based on these comparisons, the atom that has a greater ionization energy than phosphorus (P) is:
D. Chlorine (Cl)
