What is the formula for an ionic compound made of aluminum and nitrogen? A. Al3N2 B. Al2N4 C. Al3N3 D. AlN E. none of these choices is correct
The Correct Answer and Explanation is:
Correct Answer: D. AlN
Explanation
To determine the correct formula for an ionic compound made of aluminum and nitrogen, we need to understand the charges of the ions each element forms and then balance those charges to form a neutral compound.
Step 1: Determine the Ions
- Aluminum (Al) is a metal in Group 13 of the periodic table. It loses three electrons to achieve a stable electron configuration, forming a +3 cation: Al→Al3++3e−\text{Al} \rightarrow \text{Al}^{3+} + 3e^-
- Nitrogen (N) is a nonmetal in Group 15. It gains three electrons to complete its octet, forming a -3 anion: N+3e−→N3−\text{N} + 3e^- \rightarrow \text{N}^{3-}
Step 2: Balance the Charges
When forming an ionic compound, the total positive charge must balance the total negative charge. Since Al³⁺ and N³⁻ have charges of equal magnitude but opposite sign, only one aluminum ion is needed for one nitrogen ion to achieve charge neutrality: Al3++N3−→AlN\text{Al}^{3+} + \text{N}^{3-} \rightarrow \text{AlN}
This gives the formula AlN.
Step 3: Why the Other Options Are Incorrect
- A. Al₃N₂ implies an imbalance: 3(3+) = +9, 2(3−) = −6 → net charge ≠ 0.
- B. Al₂N₄ implies: 2(3+) = +6, 4(3−) = −12 → net charge ≠ 0.
- C. Al₃N₃ implies: 3(3+) = +9, 3(3−) = −9 → net charge = 0, but this simplifies to AlN (a 1:1 ratio).
- E. None of these choices is incorrect because D (AlN) is the correct choice.
Conclusion
The correct formula for the ionic compound formed between aluminum and nitrogen is AlN, which reflects the 1:1 ratio needed to balance the +3 and −3 charges of the ions.
