Plumbic nitride has four N³? (s) and three Pb?? (s). What is its chemical formula (for order of atoms as well as count)? [Pb??]? [N³?]? 4 N³? 3 Pb?? [N³?]? [Pb??]? Pb?N? None of these is correct
The Correct Answer and Explanation is:
The correct answer is: Pb₃N₄
Explanation:
To determine the correct chemical formula for plumbic nitride, we need to consider the charges and the correct ratio in which the ions combine to form a neutral compound.
Step 1: Identify the Ions
- Plumbic ion (Pb⁴⁺): This is a lead ion with a +4 charge.
- Nitride ion (N³⁻): This is a nitrogen ion with a -3 charge.
Step 2: Total Charges
We are told:
- There are 3 Pb⁴⁺ ions → total positive charge = 3 × (+4) = +12
- There are 4 N³⁻ ions → total negative charge = 4 × (−3) = −12
Since +12 and −12 add to zero, the compound is electrically neutral, which is a requirement for any stable ionic compound.
Step 3: Write the Chemical Formula
When writing ionic formulas:
- The cation (positive ion) comes first: Pb
- The anion (negative ion) comes second: N
- The subscripts indicate how many of each ion are present, based on the ratio that balances charges.
So with 3 Pb⁴⁺ and 4 N³⁻, the formula is:
Pb₃N₄
This is the simplest whole-number ratio of ions that results in a neutral compound.
Why Other Options Are Incorrect:
- Options like [Pb4+]3[N3−]4[Pb^{4+}]^3[N^{3-}]^4 describe the ions but not the chemical formula.
- “4 N³⁻ 3 Pb⁴⁺” is a ratio, not a proper formula.
- “None of these is correct” is incorrect because Pb₃N₄ is correct.
Final Answer: Pb₃N₄ ✅
