Naming Compounds

Binary Compounds Binary Compounds are divided into two broad categories: Compounds that contain a metal and a nonmetal. Compounds that contain two metals.

Metal and a Nonmetal Results in a binary ionic compound. They contain a positive ion (cation) and a negative ion (anion). To name them, we just name the ions. There are two types – Type l and Type II

Rules for Naming Type l Compounds The cation is named first and then the anion. A simple cation (obtained from a single atom) takes its name from the name of the element. A simple anion (obtained from a single atom) is named by taking the first part of the element name and adding –ide.

Common Simple Cations and Anions Cation Symbol Name Anion Symbol Name H+ hydrogen ion H– hydride Li+ lithium ion F– fluoride Na+ sodium ion Cl– chloride K+ potassium ion Br– bromide Cs+ cesium ion I– iodide Be2+ beryllium ion O2– oxide Mg2+ magnesium ion S2– sulfide Ca2+ calcium ion N3– nitride Ba2+ barium ion Al3+ aluminum ion Ag+ silver ion Zn2+ zinc ion Cd2+ cadmium ion

Type ll Binary Ionic Compounds Many metals can form more than one type of ionic compound. Example: Iron can produce Fe2+ and Fe3+ , gold can produce Au+ or Au3+ If gold is bonded to Cl, how do we know by name only what Gold ion it is.

Type ll Binary Ionic Compounds Chemists use roman numerals to signify the correct ion (how many electrons were given up by the metal in the formation of the compound). So, iron (ll) chloride is FeCl2 and iron (lll) chloride is FeCl3

Naming Binary Compounds that Contain only Nonmetals (Type lll) The first element in the formula is named first, and the full element name is used. The second element is named as though it were an anion. Prefixes are used to denote the numbers of atoms present. The prefix mono- is never used for naming the first element.

Review: Naming Binary Compounds Type l: Ionic Compounds with metals that always form the same charge. Type ll: Ionic Compounds with metals (usually transition metals) that form cations with various charges. Type lll: Compounds that contain only nonmetals.

Naming Compounds that contain Polyatomic Ions Polyatomic ions are assigned special names that you must memorize. Some contain oxygen in different amounts. The smaller number of oxygen is –ite The larger number of oxygen is –ate. If it has only one, the a prefix of hypo-is added. If it has 4, the prefix per- is added.

Naming Acids When dissolved in water, some molecules produce H+ ions (protons). These substances are called acids.