Chemical Nomenclature Naming Compounds and Writing Formulas of Ionic, Covalent, Mixed, and Acidic Compounds

Naming Binary Ionic Compounds Contain ONLY 2 ions CATION (positive) written first ANION (negative) written second 1. Give the cation its “regular” name 2. Give the anion its “root” name followed by the ending “-ide” The ratio of ions as indicated by subscripts does not affect the name

Naming Binary Ionic Compounds EXAMPLES NaCl SODIUM CHLORIDE CaF2 CALCIUM FLUORIDE K2S POTASSIUM SULFIDE Al2O3 ALUMINUM OXIDE

Naming Binary Ionic Compounds with Transition Metals Cations of transition metals may have more than one possible charge The charge of the cation of these transition metals depends on the anion it combines with The charge of the transition metal is shown by a Roman numeral in parentheses after the name of the cation The anion is named with the “-ide” ending

Naming Binary Ionic Compounds with Transition Metals EXAMPLES FeCl2 Iron (II) chloride MnO2 Manganese (IV) oxide Ni2S3 Nickel (III) sulfide CuBr Copper (I) bromide

Naming Compounds Containing Polyatomic Ions A polyatomic ion is a group of covalently bonded atoms that acts as a single unit when forming compounds The charge of the ion corresponds to the number of electrons gained or lost by the unit Each polyatomic ion MUST be memorized (name, formula, and charge) In compounds the name of the polyatomic ion is given as appropriate in the formula

Naming Compounds Containing Polyatomic Ions EXAMPLES NH4Cl Ammonium chloride KMnO4 Potassium permanganate Cu(C2H3O2)2 Copper (II) acetate Pb(SO4)2 Lead (IV) sulfate

Break

Writing Formulas of Ionic Compounds The overall charge of an ionic compound is ZERO Therefore, there must be an equal amount of POSITIVE and NEGATIVE charge The ratio of CATIONS to ANIONS is such that the resulting formula reflects an overall neutral charge

Sr+2 I-1 SrI2 Writing Formulas of Ionic Compounds Problem: Write the formula for strontium iodide Step One: Write the symbols and charges for each ion Sr+2 I-1 SrI2

Problem: Write the formula of copper (II) nitride Writing Formulas of Ionic Compounds Problem: Write the formula of copper (II) nitride Cu+2 N-3 Cu3N2

Write the formula for sodium acetate Writing Formulas of Ionic Compounds with Polyatomic Ions Write the formula for sodium acetate Na+1 C2H3O2-1 Since the charges are already EQUAL BUT OPPOSITE, you only need one of each ion in the formula. NaC2H3O2

Write the formula for ammonium sulfide Writing Formulas of Ionic Compounds Write the formula for ammonium sulfide NH4+1 S-2 (NH4)2S Use parentheses when you need more than one of a polyatomic ion The subscript outside the parentheses tell how many of this ion are needed

Write the formula for chromium (III) sulfate Writing Formulas of Ionic Compounds Write the formula for chromium (III) sulfate Cr+3 SO4-2 Cr2(SO4)3 No parentheses for the Cr because it is not a polyatomic ion!

Practice

Naming Covalent Compounds Using the Prefix System Binary covalent compounds typically contain two NONMETALS In this system, prefixes are used to indicate the number of each atom present No indication of charge or oxidation number is used in this system

Naming Covalent Compounds Using the Prefix System Mono = 1 Di = 2 Tri = 3 Tetra = 4 Penta = 5 Hexa = 6 Hepta = 7 Octa = 8 Nona = 9 Deca = 10

Naming Covalent Compounds Using the Prefix System EXAMPLES CO2 Carbon dioxide (if there is only one atom of the first element do not use a prefix – at all other times a prefix must be used) P2O5 Diphosphorus pentoxide N2O3 Dinitrogen trioxide

Writing Formulas of Covalent Compounds If named using the prefix system, indicate the number of each element with a subscript EXAMPLE: Tetraphosphorus decoxide P4O10 EXAMPLE: Dihydrogen monoxide H2O

Types of Acids Binary acids - contain the HYDROGEN cation (+1 charge) and a monatomic anion Oxyacids - contain the HYDROGEN cation (+1 charge) and a polyatomic ion that contains oxygen.

Writing Formulas of Binary Acids Binary acids contain the HYDROGEN cation (+1 charge) and a monatomic anion Prefix of the name is “Hydro-” Use the root of the anion Suffix is “-ic” Follow with the word “acid” EXAMPLES HCl is hydrochloric acid H2S is hydrosulfuric acid HF is hydrofluoric acid

Writing Formulas of Oxyacids Oxyacids contain the HYDROGEN cation (+1 charge) and a polyatomic ion that contains oxygen. Prefix corresponds to the prefix of the anion The root is from the anion Suffix is from the anion End with the word “acid”

Writing Formulas of Oxyacids Anion Anion Name Acid Prefix/Root Acid Suffix Acid Name Acid Formula SO2-2 Hyposulfite Hyposulfur- -ous Hyposulfurous Acid H2SO2 SO3-2 Sulfite Sulfur- Sulfurous Acid H2SO3 SO4-2 Sulfate -ic Sulfuric Acid H2SO4 SO5-2 Persulfate Persulfur- Persulfuric Acid H2SO5

Writing Formulas of Oxyacids EXAMPLES Nitrous Acid HNO2 Hypochlorous Acid HClO Perphosphoric Acid H3PO5 Carbonic Acid H2CO3