Question 2.4.3: a. What is the name of the compound with the formula CuCN? b......

You are asked to write the name or the formula for an ionic compound.
You are given the formula or the name of the ionic compound.
a. Copper(I) cyanide
The cation is a transition metal, and its name must include the cation charge. The cyanide ion, CN^{-}, is a polyatomic ion with a -1 charge. The single copper cation therefore has a +1 charge. The name of this compound includes the charge on the cation in Roman numerals, within parentheses.
b. Al(NO_{2})_{3}
Aluminum is in Group 3A and forms a cation with a +3 charge, Al^{3+}. The nitrite ion, NO_{2}^{-}, is a polyatomic ion whose name, charge, and formula must be memorized. Three nitrite ions are needed to provide a total -3 charge that balances the +3 charge on Al^{3+}. Parentheses are used to indicate the total number of polyatomic ions in the compound formula.