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}

\

$$\begin{tabular}{|c|c|c|c|} \\hline compound name & built model & cation to anion ratio & compound formula* \\\\ \\hline calcium bromide & & ? : ? & ?_? ?_? \\\\ \\hline \\end{tabular}$$

*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 cation is calcium, which has a \(2+\) charge:

$$ \text{Ca}^{2+} $$

The anion is bromide, which has a \(1-\) charge:

$$ \text{Br}^- $$

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.

• One \(\text{Ca}^{2+}\) ion provides a charge of \(+2\).
• Each \(\text{Br}^-\) ion provides a charge of \(-1\).

To balance the \(+2\) charge, we need two \(\text{Br}^-\) ions:

$$ 1 \times (+2) + 2 \times (-1) = 0 $$

Thus, the ratio of cation to anion is:

$$ 1 : 2 $$

Step 3: Write the compound formula

Using the ratio of \(1\) calcium ion to \(2\) bromide ions, and following the instruction to write the quantity even if it is \(1\), the formula is:

$$ \text{Ca}_1\text{Br}_2 $$

Answer:

• cation to anion ratio: 1 : 2
• Compound formula: Ca1Br2