The secret language of chemists. Chemical formulas The secret language of chemists.

Definitions Cation – positively charged ion (all metals form cations) Anion – negatively charged ion (non-metals form anions) Polyatomic ion – an ion (usually negative) that has more than one atom. Ex NO3-, OH-

Rules for ionic formulas Ex. NaCl H2O CaO The cation is written first, then the anion. All compounds are neutral so the sum of the charges must be zero. Subscripts indicate the number of that atom present in the compound. Formulas are written with subscripts that have the smallest whole number ratio.

Naming acids Acids are compounds that are capable of producing an H+ ion when they break apart. There are two types of acid – those which contain oxygen and those that do not.

Acids that do not contain oxygen Acids that do not contain oxygen are made of hydrogen and one other element. HCl HF To name these acids, write the prefix hydro- followed by the root name of the other element, followed by the suffix – ic acid. Hydrochloric acid hydrofluoric acid

Acids that contain oxygen Acids that contain oxygen are made of hydrogen and a polyatomic ion. H2SO4 HNO2 If the polyatomic ion ends with –ate, the acid’s name ends with –ic, if the polyatomic ends with –ite, then the acid’s name ends with –ous. (ateic iteous) SO4 is sulfate so it is sulfuric acid NO2 is nitrite so it is nitrous acid

Writing formulas from names Use the acid name to determine what the anion is, and determine the formula when combined with H+ Sulfuric acid hydrofluoric acid H+ (SO4)2- H+ F- H2SO4 HF