Naming Binary Ionic Compounds

What is a binary ionic compound? IONIC COMPOUND – Formed from ionic bonds – Metal and nonmetal Left of stepline on PT=metal Right of stepline on PT=nonmetal BINARY – Prefix “bi” means 2 – A binary compound contains teo different kinds of elements

A Common Example NaCl – Na=sodium=metal=cation – Cl=chlorine=nonmetal=anion – Two elements joined by an ionic bond Na loses electron to form positive ion Cl gains electron to form negative ion Ions are attracted by electrostatic charges

How do we name it? Name the metal Na Sodium Name the non-metal with an “-ide” ending Cl Chlorine Chloride

NaCl sodium chloride

Is it always this easy? Almost…but not quite! Group 1,2, and 13 metals have charges determined by their position on the periodic table…1+, Ag is always 1+ Cd is always 2+ Zn is always 2+

Transition metals The charges of transition metal cations (and a few others under the stepline) vary The charge of these cations must be calculated to balance the negative charge of the anions involved

CuS is copper (II) sulfide Copper can have different charges What is it paired up with and what ratio is needed to have a net charge of zero? The anion is sulfide – Sulfur produces a sulfide ion which is 2-. (You know this from the periodic table.) The cation is copper – One Cu is present, so its charge must be 2+ to balance the 2- charge from the S Name cation, show charge as Roman numeral in parentheses, name anion with -ide ending.

Fe 2 S 3 is iron (III) sulfide Sulfide is 2- (from its position on periodic table) There are 3 sulfide 3 x 2- = 6- Iron can have different charges 2 iron ions balance a 6- charge 2 x ? = 6+ Iron’s charge in this compound is 3+ Name cation, show charge as Roman numeral in parentheses, name anion with -ide ending. Reverse criss-cross!