Answer
🎯 Identifying the Incorrect Orbital Notation
📘 Orbital Validity Rules
The principal quantum number n defines the energy level.
The angular momentum quantum number l (sublevel) must satisfy:
0 ≤ l ≤ (n – 1)
| Sublevel | Symbol | l value |
|---|---|---|
| s | s | 0 |
| p | p | 1 |
| d | d | 2 |
| f | f | 3 |
🔍 Orbital Notation Analysis
- 2s: n = 2, l = 0 → ✔️ Correct
- 3py: n = 3, l = 1 → ✔️ Correct
- 3f: n = 3, l = 3 → ❌ Incorrect
- 4dxy: n = 4, l = 2 → ✔️ Correct
- 4s: n = 4, l = 0 → ✔️ Correct
🚫 Final Conclusion
The orbital notation 3f is invalid because the f sublevel (l = 3) is only permitted when n ≥ 4. For n = 3, the maximum allowed l is 2 (d sublevel).