To solve the question regarding the oscillating trend of ionization energy, we will analyze the trends in different groups of the periodic table, particularly focusing on Group 13 (the Boron family).
### Step-by-Step Solution:
1. **Understanding Ionization Energy**:
- Ionization energy is the energy required to remove the outermost electron from an atom.
- Generally, as we move down a group in the periodic table, the size of the atoms increases, leading to a decrease in ionization energy because the outermost electron is further from the nucleus and experiences less nuclear attraction.
2. **Analyzing Group 12 (Zinc Family)**:
- In Group 12, which includes Zinc (Zn), Cadmium (Cd), and Mercury (Hg), the trend is straightforward.
- As we move down the group, the atomic size increases, and thus the ionization energy decreases. However, there is no oscillating trend here; it is a consistent decrease.
3. **Analyzing Group 13 (Boron Family)**:
- In Group 13, which includes Boron (B), Aluminum (Al), Gallium (Ga), Indium (In), and Thallium (Tl), we observe a unique trend.
- The expected trend would be a decrease in ionization energy as we move down the group due to increasing atomic size. However, due to the effects of d-electron shielding in Gallium, the ionization energy does not follow a simple decreasing trend.
- The ionization energies for these elements show fluctuations:
- B > Al (decrease)
- Al < Ga (increase)
- Ga > In (decrease)
- In < Tl (increase)
- This results in an oscillating trend where the ionization energy first decreases, then increases, and continues to oscillate.
4. **Conclusion**:
- The oscillating trend of ionization energy is specifically observed in Group 13 (the Boron family). Therefore, the answer to the question is **Group 13**.
### Final Answer:
The oscillating trend of ionization energy is found in **Group 13 (Boron Family)**.
