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:

compound name: aluminum oxide
built model: al^{3+} and o^{2-} blocks fitting together
cation to anion ratio: 2 : 3
compound formula: al_2o_3

cation: ca^{2+}
anion: o^{2-}

compound name: calcium oxide
built model: empty
cation to anion ratio: ? : ?
compound formula*: ?_? ?_?

*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:

🆕 New Concept Discovered: Writing Ionic Formulas
Finding the simplest ratio of ions to create a neutral compound.

Step 1: Identify the charges of the ions

The cation is calcium:

$$ \text{Ca}^{2+} \quad (\text{charge} = +2) $$

The anion is oxide:

$$ \text{O}^{2-} \quad (\text{charge} = -2) $$

Step 2: Determine the ratio for a neutral compound

To make a neutral compound, the total positive charge must equal the total negative charge.

Since one calcium ion has a \(+2\) charge and one oxide ion has a \(-2\) charge:

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

We need exactly 1 calcium ion for every 1 oxide ion.

The cation to anion ratio is:

$$ 1 : 1 $$

Step 3: Write the compound formula

Using the ratio of \(1 : 1\), we write the chemical symbols with their quantities as subscripts.

Following the instruction to include the quantity even if it is 1:

$$ \text{Ca}_1\text{O}_1 $$

Answer:

• cation to anion ratio: 1 : 1
• Compound formula: Ca₁O₁ (or entered in the boxes as Ca 1 O 1)