SNC 1D1 –Nomenclature Review Chemical Nomenclature: Chemical nomenclature is decided by IUPAC (international union of pure and applied chemistry.) This organization establishes rules and guidelines for naming organic and inorganic compounds. It is an easy-to-use system that identifies the composition of every compound. It is a chemical language.

Binary Compounds: In ionic bonds the simplest compounds are called binary compounds. These are made up of 2 types of monoatomic ions (an ion made up of only 1 charged atom.) The metal is stated in full, the non-metal ion has the ide suffix added. NaCl – sodium chloride LiBr – lithium bromide Binary compounds can be made up of more than two ions as long as there are only 2 kinds of atoms Ex. aluminum oxide – Al2O3.

Valence: The charge on the ion is sometimes called the valence. The charge on an atom is sometimes also called the oxidation number. This is not to be confused with valence electrons which are the electrons found in the outermost orbital of an atom.

Writing the Formulas of Ionic Compounds: Write the symbols in the order they should appear in the compound (metals first, non-metals second). For magnesium chloride: Mg Cl Write the valences (ionic charges) above the symbols. Mg Cl Using the criss-cross rule, make the valences subscripts: MgCl2 (note the subscript 1 for Mg is assumed and signs are omitted) +2 -1 +2 -1

Multivalent Metals: (table 2 pg. 92) Some metals (usually the transition metals) have more than one valence or charge. Ex Fe 2+ or Fe 3+. Your periodic table shows the most common ion of each element. An element like iron can form either FeCl2 or FeCl3 depending on the valence of iron. Roman numerals are used to express the charge on the ion. Ex. iron (II) chloride = FeCl2 iron (III) chloride = FeCl3

Polyatomic Ions: Compounds with more than 2 atoms are called tertiary compounds. Usually compounds of a metal ion and a polyatomic ion. Polyatomic ions are a group of ions that bond together with a net charge. When writing chemical formulas the polyatomic ion is treated like a regular ion. Ex. calcium nitrate Ca 2+ NO3 1- → Ca(NO3)2 Brackets are placed around polyatomic ions when there are 2 or more ions in the compound.

Hydrates: Some tertiary compounds (metal + polyatomic ion) contain molecules of water within their crystal structures, these compounds are called hydrates. When hydrates are heated this water is released from the compound. This is called water of hydration. When this water is removed the product is called anhydrous. CuSO4 • 5H2O – copper (II) sulfate pentahydrate CuSO4 - anhydrous copper (II) sulfate The prefixes for hydrates in compounds are given in table 4 pg. 96.

Number of Water Molecules Prefix 1 mono 2 di 3 tri 4 tetra 5 penta 6 hexa

Oxyacids Compounds made by combining hydrogen with an oxyanion are called oxyacids. These compounds can be named according to 2 naming systems: IUPAC H2SO5(aq) - aqueous hydrogen persulfate H2SO4(aq) - aqueous hydrogen sulfate H2SO3(aq) - aqueous hydrogen sulfite H2SO2(aq) - aqueous hydrogen hyposulfite This naming system applies for all other oxyacids (acids made from NO3 -1, CO3-2, ClO3-1, PO4-3 etc.)

H2SO5(aq) H2SO4(aq) H2SO3(aq) H2SO2(aq) Classical Naming System According to the classical naming system the suffixes of the acids change depending on the number of oxygen atoms in the polyatomic ion. Acid IUPAC Classical H2SO5(aq) aqueous hydrogen persulfate persulfuric acid H2SO4(aq) aqueous hydrogen sulfate sulfuric acid H2SO3(aq) aqueous hydrogen sulfite sulfurous acid H2SO2(aq) aqueous hydrogen hyposulfite hyposulfurous acid