Question

fill in the name and empirical formula of each ionic compound that could be formed from the ions in this table:

cation	anion	empirical formula	name of compound
$co^{3 +}$	$i^{-}$
$na^{+}$	$i^{-}$
$ca^{2 +}$	$i^{-}$

Explanation:

Step1: Determine formula for $Co^{2 +}$ and $I^-$

The charges must balance. Two $I^-$ ions are needed for one $Co^{2+}$ ion. So the empirical formula is $CoI_2$. The name is cobalt(II) iodide.

Step2: Determine formula for $Co^{3+}$ and $I^-$

Three $I^-$ ions are needed for one $Co^{3+}$ ion to balance the charges. The empirical formula is $CoI_3$. The name is cobalt(III) iodide.

Step3: Determine formula for $Na^+$ and $I^-$

One $Na^+$ and one $I^-$ combine to balance charges. The empirical formula is $NaI$. The name is sodium iodide.

Step4: Determine formula for $Ca^{2+}$ and $I^-$

Two $I^-$ ions are required for one $Ca^{2+}$ ion. The empirical formula is $CaI_2$. The name is calcium iodide.

Answer:

cation	anion	empirical formula	name of compound
$Co^{3+}$	$I^-$	$CoI_3$	cobalt(III) iodide
$Na^+$	$I^-$	$NaI$	sodium iodide
$Ca^{2+}$	$I^-$	$CaI_2$	calcium iodide