#FeI_2# is an ionic compound called Ferrous Iodide
or Iron (II) Iodide.
Iron is a transition metal and has oxidation states of #Fe^(+2)# or #Fe^(+3)#. Since the iodide ion only has a charge of #I^-1# and there are two iodide ions in the molecule, this informs us that the iron is in the #Fe^(+2)# oxidation state.
There are two types of naming, the Systemic or Stock name using a roman numeral to identify the oxidation state therefore, we use
Iron (II) for the #Fe^(+2)# oxidation state. Or we can use the common name identifying the #Fe^(+2)# oxidation state as ferrous. The lower oxidation state ends in the suffix -ous and the higher oxidation state will end in the suffix -ic, #Fe^(+2)# is ferrous and #Fe^(+3)# is ferric.
#FeI_2# is called Ferrous Iodide or Iron (II) Iodide.
#FeI_3# is called Ferric Iodide or Iron (III) Iodide
Other examples of transition metals would include #Cu^(+1)# is cuprous, Copper (I) and #Cu^(+3)# is cupric, Copper (II) or #Sn^(+2)# is stannous, Tin (II) and #Sn^(+4)# is stannic, Tin (IV).
I hope this was helpful.
SMARTERTEACHER
