Compounds composed of two kinds of atoms or monatomic ions. Naming Rules Name of metal first (cation) Name of non-metal second (anion) The ending of the non-metal changes to –ide. e.g. sodium chloride

Rules for deciphering a formula from the atoms present in the name: 1.Write the symbol for each compound (metal first). 2.Write the charge of the most stable ion above each symbol 3.Crisscross these numbers to represent the subscript for the number of atoms that need to be present of the opposite element. 4.Divide these numbers by the lowest common factor to represent possible double or triple bonds. 5.Do not write the number one, it is represented by the chemical symbol

What is the formula of aluminium oxide? AlO +3-2 Al 2 O 3 2 aluminium ions are needed for 3 oxide ions 2 : 3 Symbol Balance the number of ions Ion charge Ratio of ions Formula AlAl 3+ AlAl 3+ O O 2- O O 2 electrons for each oxygen atom

Many transition metals can have more than one valence. In IUPAC naming we use Roman numerals to represent which multivalent version is present E.g. CuCl or CuCl 2 copper (I) chloride copper (II) chloride Classical naming does this by using a suffix (–ic or –ous) following the metal’s Latin root lower valence = -ous & higher valence = -ic E.g. CuCl or CuCl 2 cuprous chloride cupric chloride

May be called tertiary compounds as they contain 3 different elements. End in –ate or –ite. Usually a metal cation and a polyatomic anion A polyatomic ion containing oxygen is called an oxyanion. e.g. NO 3 - Nitrate Prefixes and sufixes indiate the # of oxygen atoms per prefix = I more oxygen atom ate ending = parent ion (typically the most stable / common) ite ending = 1 less oxygen hypo prefix, ite ending = 2 less oxygen

Formed from tertiary ionic compounds that contain water molecules within a crystal structure They absorb water – like SiO 2 in new purses The hydrate breaks down in the presence of heat releasing water vapour and an ionic compound When the water is removed it is called anhydrous

To name an hydrate, write the name of the ionic compound followed by the word water prefixed by the Greek prefix for the number of water molecules e.g. copper (II) sulphate pentahydrate To write the formula for an hydrate, write the formula for the ionic compound followed by a dot, the number of the Greek prefix, and H 2 O e.g. Ba(OH) 2  8H 2 O