Naming the Inorganic Compounds Kavita Gupta

Classification of Compounds for Naming Purposes Ionic compounds Formed by a metal and a nonmetal or a polyatomic ion Generally solids in the natural state Ex: NaCl, K 2 SO 4, PbCO 3, ZnS, KMnO 4 Molecular Compounds Made up exclusively of nonmetals Generally liquids or gases in natural state Ex: NO 2, CO 2, P 2 O 5, H 2 O Acids Begin with a H Generally present as aqueous solutions or gases HCl, HClO 4, H 2 CO 3, HNO 3, HC 2 H 3 O 2, HCOOH

Naming the Ionic Compounds Ionic Compounds- made of a cation (either from group 1, group 2 or transition metals) and an anion (monoatomic or polyatomic anion) Anions are named the same for any ionic compounds. Monoatomic anion ends in –ide and polyatomic anion is named just like the name of the polyatomic anion. Cation from Transition Metal Old Way of Naming: Lower of the two charges cation name ends in –ous and higher of the two charges cation name ends in – ic. Stock Way:Name the cation as its element, followed by its oxiation number (Charge) within parenthesis. Cation from Group 1 (alkali metal) or Group 2 (alkaline earth) Name the cation as the element.

Practice on Naming Ionic Compounds Na 2 SO 4 KClO 4 Ionic Compounds with Cations from Group 1 and 2 PbS Cu(NO 3 ) 2 Ionic Compounds with cations from transition metals

Criss Cross Method for writing the formula for an ionic compound given its name Sodium Sulfide Potassium Nitrate Ferrous Sulfate Ammoniu m Carbonate Cupric Nitride Criss-cross method involves bringing the valency (charge) of one element down as a subscript next to the other element or polyatomic ion. Practice writing the formula of the following compounds by using the criss-cross method.

Naming the Molecular Compounds There are two ways of naming the molecular compounds Prefix Way Use prefixes mone-, di-, tri- etc. to indicate number of atoms of each element. Do not use mono before the first element. Ex. N2O5- Di nitrogen Pentoxide CO2- Carbon Dioxide Stock Way Write name of the first element followed by its oxidation state in parenthesis Ex: N2O5– Nitrogen (V) Oxice CO2- Carbon (IV) Oxide CO – Carbon (II) Oxide

Naming the Acids To name an acid, first check to see if it is an oxy acid or not. Presence of Oxygen in the chemical formula of an acid indicates an oxyacid. Ex. HCl is not an oxyacid but HClO4 is an oxyacid. Oxyacids: Anion ending decides the name of the acid. If anion ends in –ate, then acid is –ic acid, if anion ends in –its, then acid is –ous acid. Ex. HClO4  Perchloric Acid (anion perchlorate) Ex. HClO3  Chloric Acid (anion Chlorate) To name an acid without oxygen, start naming with Hydro- followed by the name of anion ending in –ic Acid. Ex. Ex. HCl  Hydrochloric acid

Naming of Complex Compounds Please go back to Ch 2 in the ibook for details on the naming of the complexes or coordination compounds. Name cation first followed by anion. Within a complex, transition metal is named first with its charge listed within parenthesis, followed by ligands and then anion. If complex is anion, then its name ends in –ate.

Naming of the Hydrates Hydrates are ionic compounds that have loosely attached water molecules to them. Ex. CuSO 4. 5H 2 O. To name the hydrates, name the ionic compound first and then use the prefix that indicates the number of water molecules attached. Ex. The name of CuSO 4.5H 2 O is Cupric Sulfate pentahydrate or Copper (II) Sulfate pentahydrate.

Common Cations with Variable Valency

Common Polyatomic Ions