Question

drag the ions together in such a way as to make a rectangle, from top down, in the \build model\ portion of the table below, then fill in the rest of the table. see the sample completed table here:

\

$$\begin{tabular}{|c|c|c|c|} \\hline compound name & built model & cation to anion ratio & compound formula \\\\ \\hline aluminum oxide & \\begin{tabular}{c} \\text{al}^{3+} \\\\ \\text{al}^{3+} \\end{tabular}$$

\

$$\begin{tabular}{c} \\text{o}^{2-} \\\\ \\text{o}^{2-} \\\\ \\text{o}^{2-} \\end{tabular}$$

& 2 : 3 & \text{al}_2\text{o}_3 \\\\
\hline
\end{tabular}

\

$$\begin{tabular}{|c|c|c|c|} \\hline compound name & built model & cation to anion ratio & compound formula* \\\\ \\hline iron(ii) nitride & & ? : ? & ?_? ?_? \\\\ \\hline \\end{tabular}$$

*if only one ion is needed in a formula, it is left off, but for this practice you will need to type in the quantity, even a 1.

Explanation:

⚡ Using what you learned: formation of ionic and covalent bonds

Step 1: Identify the charges of the ions

The compound is iron(II) nitride.

• The cation is iron(II): \(\text{Fe}^{2+}\) (charge of \(+2\))
• The anion is nitride: \(\text{N}^{3-}\) (charge of \(-3\))

Step 2: Balance the charges to find the ratio

To form a neutral ionic compound, the total positive charge must equal the total negative charge. We find the least common multiple (LCM) of the charges \(2\) and \(3\), which is \(6\).

• Total positive charge needed: \(+6\)

$$ 3 \times (+2) = +6 \implies 3 \text{ iron(II) ions } (\text{Fe}^{2+}) $$

• Total negative charge needed: \(-6\)

$$ 2 \times (-3) = -6 \implies 2 \text{ nitride ions } (\text{N}^{3-}) $$

This gives a cation-to-anion ratio of \(3 : 2\).

Step 3: Write the chemical formula

Using the quantities determined in Step 2:

• Number of \(\text{Fe}\) atoms = \(3\)
• Number of \(\text{N}\) atoms = \(2\)

The compound formula is written as \(\text{Fe}_3\text{N}_2\).

Answer:

• cation to anion ratio: \(3 : 2\)
• Compound formula: \(\text{Fe}_3\text{N}_2\) (entered as \(\text{Fe}\) \(\underline{3}\) \(\text{N}\) \(\underline{2}\) in the blanks)