1. RIF:
Name: Rubidium fluoride
Rules:
The cation (positive ion) is named first, followed by the anion (negative ion).
The cation is named by its element name, followed by the suffix "-ium".
The anion is named by taking the root of the element name and adding the suffix "-ide".
2. CuO:
Name: Copper(II) oxide
Rules:
The cation is named first, followed by the anion.
The cation is named by its element name.
Since copper can have multiple oxidation states, the Roman numeral in parentheses indicates its specific oxidation state in this compound (Cu2+).
The anion is named by taking the root of the element name and adding the suffix "-ide".
3. (NH4)2C2O4:
Name: Ammonium oxalate
Rules:
This compound is an ionic compound formed by a polyatomic cation (ammonium) and a polyatomic anion (oxalate).
The polyatomic cation is named by its complete name (ammonium).
The polyatomic anion is named directly (oxalate).
A subscript is used to indicate the number of each polyatomic ion present in the formula.