Chemistry 111/112 Chapter Nine: Chemical Names and Formulas

Naming Ions Ions form ionic compounds – mainly monatomic ions which consist of a single atom with a positive or negative charge Metals tend to lose e-, forming a positive ion (cation) When atoms gain e-, they become a negative ion (anion) Their name is changed using the suffix –ide

Ions of Transition Metals Many form cations with more than one charge – The charge is determined by the number of e- lost – When naming these ions, use Roman numerals to determine which charge is being used When a transition metal only has one charge, Roman numerals do not have to be used Table 9.2, p. 255

Polyatomic Ions These ions are composed of more than one atom but only have one overall charge They behave as a unit and are not separated Most of their suffixes are –ite or –ate When they form ionic compounds, the ending of their name does not change Table 9.3, p. 257

Naming Binary Ionic Compounds A binary compound is composed of two elements and can either be ionic or molecular If it is ionic and you know its formula, you can write its name – Always begins with the cation – The name does not change – If there is more than one charge, indicate it with a Roman numeral – Always ends with a nonmetallic anion – The name ends in –ide

Writing Formulas for Binary Ionic Compounds If you know the name, you can write its formula Write the symbol of the cation with the charge Do the same thing for the anion Criss cross the charges Reduce to lowest terms

Example Write the name of the following compounds: CaCl 2 Fe 2 O 3 Write the formula of the following compounds: barium sulfide nickel (II) fluoride Q , page 263; Q. 12 – 13, page 265

Naming Compounds with Polyatomic Ions When a compound’s formula has more than two capital letters Identify the polyatomic ion Name the metallic cation Name the nonmetallic anion – do not change its ending Ex. LiCN = lithium cyanide, NH 4 OH = ammonium hydroxide, CaCO 3 = calcium carbonate