Inorganic Nomenclature

The names and formulas of compounds are the "vocabulary" of chemistry.  In a chemical formula, symbols for the elements and numerical subscripts show the type and number of each atom present in a single unit of that compound.  The most familiar type of chemical formula is called a molecular formula and it shows the elements with subscripts to give the actual number of each element present in each unit of the compound.  An environmentally important compound has the molecular formula, NO₂ indicating that one atom of nitrogen is bonded to two atoms of oxygen. 

The empirical formula is used to identify all compound with the same ratio of atoms of each element. The empirical formula NO₂ could refer to both nitrogen dioxide, with a molecular formula of  NO₂ and dinitrogen tetroxide with a molecular formula of N₂O₄. 

The chemical formula shows the actual number of atoms and the bonds between them. Ionic compounds do not strictly speaking form molecules and so they cannot have "molecular" formulas. Consequently, the chemical formula is used to name ionic compounds.

There are millions of chemical compounds so the task of providing a unique and recognizable system for naming these compounds is a herculean task.  In the end, the only way to remember the names for particular compounds is to use them frequently, or to find excellent reference material.  Some general rules for nomenclature are outlined here.

Ionic Compounds

 Ionic compounds are formed when two oppositely charged species come together.  The electron(s) move closer to the anion(s)  forming a network of cations and ions in a crystal.  The electron(s) from the cation is transfered to the anion and the compound held together by the strong electrostatic attraction between the oppositely charged ions.  The charged species can be monotomic ions like the calcium ion, Ca²⁺ and the bromide ion, Br^1-, or  polyatomic ions like the ammonium ion NH₄⁺ and the chlorite ion ClO^-.

You can practice naming polyatomic ions using this calculator.

To complicate matters, some elements form more than one charged  ion and the name needs to convey enough information to identify the particular charge.  For example, Fe, iron, forms two different ions, Fe²⁺ and Fe³⁺ . The names and formulas of the ionic compounds of iron always include the charge on the ion noted as a roman numeral in parenthesis after the metal name or element symbol for iron.

Naming Ionic Compounds The cation (+ ion) always goes first followed by the anion (-ion). The name of the cation is the same as the metal. The name of the anion takes the root of the non-metal and adds the suffix "ide". Polyatomic ions retain their names. For example: the NH4+ ammonium ion and the chlorite ion, ClO- form a compound named ammonium chlorite. A metal that forms more than one ion is named by using the metal name but adding the charge on the ion in roman numerals surrounded by parenthesis as in: Iron(II)chloride Fe(II)Cl2and Fe(III)Cl3, Iron(III)chloride.

Ionic Formulas The positive charge of the cation(s) must be balanced by an equal negative charge coming from the anion(s) involved in the ionic bond.  For example:   Ca2+and Br1-ions forms CaBr2   NH4+andClO-ions form the compound, NH4ClO. Ca2+ and ClO- ions form the compound,  Ca(ClO)2. Fe3+ and the chloride ion, Cl-, form the compound, Fe(111)Cl3

There are a number of online search engines listed in the TOOLs menu that can help you with nomenclature. You might try this website to begin a review of nomenclature.