Which of the following is the correct chemical formula for strontium nitride?

• A. SrN
• B. Sr2N3
• C. SrN2
• D. Sr3N2

Answer: (D)

Verified step by step guidance

1. Identify the charges of the ions involved: Strontium (Sr) is an alkaline earth metal in Group 2, so it typically forms a Sr^{2+} ion. Nitrogen (N) forms the nitride ion, N^{3-}.
2. Determine the ratio of ions needed to balance the overall charge to zero. Since Sr^{2+} has a +2 charge and N^{3-} has a -3 charge, find the smallest whole number ratio of Sr^{2+} to N^{3-} that results in a neutral compound.
3. Use the least common multiple (LCM) of the charges to find the ratio: The LCM of 2 and 3 is 6. To get a total positive charge of +6, you need 3 Sr^{2+} ions (3 × +2 = +6). To get a total negative charge of -6, you need 2 N^{3-} ions (2 × -3 = -6).
4. Write the chemical formula by placing the number of each ion as subscripts: Sr has 3 ions and N has 2 ions, so the formula is Sr_{3}N_{2}.
5. Confirm that the formula Sr_{3}N_{2} is electrically neutral and correctly represents strontium nitride.