Question

fill in the name and empirical formula of each ionic compound that could be formed from the ions in this table.
some ionic compounds
cation anion empirical formula name of compound
$mn^{2 + }$ $no_{2}^{-}$
$ca^{2 + }$ $cro_{4}^{2 - }$
$fe^{3 + }$ $cn^{-}$

Explanation:

Step1: Determine formula for $Mn^{2 +}$ and $NO_{2}^{-}$

The compound is formed by balancing charges. Two $NO_{2}^{-}$ are needed for one $Mn^{2+}$. So the empirical formula is $Mn(NO_{2})_{2}$. The name is Manganese(II) nitrite.

Step2: Determine formula for $Ca^{2+}$ and $CrO_{4}^{2 -}$

The charges balance in a 1:1 ratio. The empirical formula is $CaCrO_{4}$. The name is Calcium chromate.

Step3: Determine formula for $Fe^{3+}$ and $CN^{-}$

Three $CN^{-}$ are needed for one $Fe^{3+}$. The empirical formula is $Fe(CN)_{3}$. The name is Iron(III) cyanide.

Answer:

cation	anion	empirical formula	name of compound
$Ca^{2+}$	$CrO_{4}^{2 -}$	$CaCrO_{4}$	Calcium chromate
$Fe^{3+}$	$CN^{-}$	$Fe(CN)_{3}$	Iron(III) cyanide