To determine the correct formula for the compound formed by [tex]\( Ca^{2+} \)[/tex] (calcium ion) and [tex]\( NO_2^{-} \)[/tex] (nitrite ion), we need to balance the charges of the ions. Here is the step-by-step process:
1. Identify the charges of the ions:
- Calcium ion ([tex]\( Ca^{2+} \)[/tex]) has a charge of [tex]\( +2 \)[/tex].
- Nitrite ion ([tex]\( NO_2^{-} \)[/tex]) has a charge of [tex]\( -1 \)[/tex].
2. Balance the total positive and negative charges:
- To neutralize the [tex]\( +2 \)[/tex] charge of one calcium ion, we need two nitrite ions because each nitrite ion has a [tex]\( -1 \)[/tex] charge.
- The total charge for [tex]\( Ca^{2+} \)[/tex] is [tex]\( +2 \)[/tex].
- The total charge for [tex]\( 2 \times NO_2^{-} \)[/tex] is [tex]\( 2 \times (-1) = -2 \)[/tex].
The charges are balanced:
[tex]\[
+2 + (-2) = 0
\][/tex]
3. Determine the empirical formula:
- We need one calcium ion ([tex]\( Ca^{2+} \)[/tex]) and two nitrite ions ([tex]\( NO_2^{-} \)[/tex]).
4. Write the chemical formula:
- When combining one [tex]\( Ca^{2+} \)[/tex] ion with two [tex]\( NO_2^{-} \)[/tex] ions, we write the formula as [tex]\( Ca(NO_2)_2 \)[/tex].
5. Select the correct option:
- The correct formula for the compound is [tex]\( Ca(NO_2)_2 \)[/tex].
Therefore, the correct answer is:
D. [tex]\( Ca\left( NO_2 \right)_2 \)[/tex]
