Problems and exercisesEighteen Electrons
1. The iron of ferrocyanide
Iron (Z = 26) has the configuration [Ar] 3d6 4s2. In the [Fe(CN)6]4− ion it is present as Fe2+. How many electrons does the iron contribute, and how many the six cyanides?
2. Chromium hexacarbonyl
Chromium contributes six valence electrons and each carbon monoxide molecule, CO, one pair. How many CO molecules does it need to surround itself with 18 electrons?