Which is the correct formula for the compound formed between beryllium and nitrogen?

• A. Be3N2
• B. BeN2
• C. Be2N3
• D. BeN

Answer: (A)

Verified step by step guidance

1. Identify the charges of the ions formed by beryllium and nitrogen. Beryllium (Be) is in group 2, so it typically forms a +2 charge (Be^{2+}). Nitrogen (N) is in group 15 and typically forms a -3 charge (N^{3-}).
2. Write the ions with their charges: Be^{2+} and N^{3-}. The goal is to combine these ions in a ratio that results in a neutral compound, meaning the total positive charge equals the total negative charge.
3. Find the lowest common multiple (LCM) of the charges 2 and 3, which is 6. This means the total positive charge should be +6 and the total negative charge should be -6 to balance the compound.
4. Determine how many beryllium ions are needed to reach +6 charge: since each Be^{2+} contributes +2, you need 3 Be^{2+} ions (3 × +2 = +6). Determine how many nitrogen ions are needed to reach -6 charge: since each N^{3-} contributes -3, you need 2 N^{3-} ions (2 × -3 = -6).
5. Write the formula by combining the ions in the ratio found: 3 beryllium ions and 2 nitrogen ions, resulting in the formula Be_{3}N_{2}.