Lesson 3.2 – Naming Compounds J. Venables Northwestern High School Chemistry 1 Honors

Cations formed from a metal have the same name as the metal. Naming of compounds, nomenclature, is divided into organic compounds (those containing C) and inorganic compounds (the rest of the periodic table). Cations formed from a metal have the same name as the metal. Example: Na+ = sodium ion. If the metal can form more than one cation, then the charge is indicated in parentheses in the name. Examples: Cu+ = copper(I); Cu2+ = copper(II). Cations formed from non-metals end in -ium. Example: NH4+ = ammonium ion.

Example: Cl- is ____________. Negative Ions Monatomic anions (with only one atom) are called -ide. Example: Cl- is ____________. Exceptions: hydroxide (OH-), cyanide (CN-), peroxide (O22-). Polyatomic anions (with many atoms) containing oxygen end in -ate or -ite. (The one with more oxygen is called -ate.) – see sheet. Examples: NO3- is nitrate, NO2- is _______.

Chemical nomenclature is a systematic way of naming compounds. Name the cation followed by the anion. For monatomic cations use the element name. For monatomic anions, use the root element name and the suffix –ide. To distinguish between different oxidation states of the same element, the oxidation state is written in parentheses after the name of the cation. (no roman numerals for group 1, group 2, Al, Zn, Cd, Ag) When the compound contains a polyatomic ion, name the cation followed by the name of the polyatomic ion.

Naming Ionic Compounds Name the cation then anion for the ionic compound. Example: BaBr2 = barium bromide. Examples – Name each: Ca(HSO3)2 Ba(ClO3)2 Na3N Al(CN)3 (NH4)3PO4 LiNO3 Cu(NO2)2

Naming Ionic Compounds Name the cation then anion for the ionic compound. Example: BaBr2 = barium bromide. Examples – Name each: Ca(HSO3)2 calcium hydrogen sulfite Ba(ClO3)2 barium chlorate Na3N sodium nitride Al(CN)3 aluminum cyanide (NH4)3PO4 ammonium phosphate LiNO3 lithium nitrate Cu(NO2)2 copper (II) nitrite

Examples of Writing Formulas Example: barium chlorate = Ba(ClO3)2. Examples – Write the formula for each: Ammonium chloride Potassium carbonate Aluminum sulfate Magnesium acetate Cobalt (III) nitrate Lead (IV) bromide Mercury (II) chlorite

Examples of Writing Formulas Example: barium chlorate = Ba(ClO3)2. Examples – Write the formula for each: Ammonium chloride NH4Cl Potassium carbonate K2CO3 Aluminum sulfate Al2(SO4)3 Magnesium acetate Mg(C2H3O2)2 Cobalt (III) nitrate Co(NO3)3 Lead (IV) bromide PbBr4 Mercury (II) chlorite Hg(ClO2)2

Naming Binary Molecular (Covalent) Compounds The first element is always named first using the entire element name. The second element is named using its root and adding the suffix –ide. Prefixes are used to indicate the number of atoms of each element in a compound.

Examples Dinitrogen tetroxide Sulfur hexafluoride Dihydrogen monoxide P2O5 XeF4 PF3

Examples Dinitrogen tetroxide N2O4 Sulfur hexafluoride SF6 Dihydrogen monoxide H2O P2O5 diphosphorus pentoxide XeF4 xenon tetrafluoride PI3 phosphorus triiodide

Names and Formulas for Acids Acids are compounds that start with hydrogen (H). H is bonded to a negative ion The names of acids are related to the names of anions: -ide becomes hydro-….-ic acid; -ate becomes -ic acid; -ite becomes -ous acid.

Examples HCl HNO3 H2SO3 Chlorous acid Perbromic acid Hydrosulfuric acid

Examples HCl Hydrochloric acid HNO3 Nitric acid H2SO3 Sulfurous acid Chlorous acid HClO2 Perbromic acid HBrO4 Hydrosulfuric acid H2S