Ionic Compounds 9 24 13 Charge on compound must become zero NaCl o Na loses electron o Cl gains electron o Na o Cl o One to one ratio sodium to chloride to achive balance MgCl2 Gains two cl ions in order to be balanced Each chloride atom will gain one from one magnesium Subscript 2 denotes that there are two chloride ions Ratio determined just from name Magnesium always makes 2 Chloridine always makes 1Na2S Two Na atome lose one valence electron each and one S atom gains two electrons Formula for ionic compounds Lowest possible ratio is 1 2 No such thing as a single neutral particle of an ionic compound Formula unit o The formula that identifies the smallest neutral unit of an ionic compound Naming monoatomic ions Monoatomic ions derived from 1 atom Cations have the same name of the element o Anion ends in ide NaF o Sodium Flouride MgBr2 o Magnesium Bromide What compounds do you need to name Carbon Hydrogen Oxygen Nitrogen Phosphoros sodium potassium calcium mg sinc aluminin chlorine bromine fluorine sulfer Ions formed from metals with variavle charge no need to memorize Polyatomic ions that you are required to memorize Naming ionic compound with two elements Identify cation and anion Name cation first o Then anion We do not use prefixes to denote number of ions o Comes from the name Don t show charge in formula Feedback CaO o Calcium Oxide KBr o Potassium Bromide Al2O3 o Alumninium oxide MgCl2 o Magnseium Chloride NaBr Na2S Na3N AlBr3 Al2S3 AlN Transition metals form postitive ions Most transtions metals and group 4 metals form 2 or more cations Exceptions are o Zn2 Ag Cd2 form only one ion Metals with variable change The names of transition metals with two or more positiove ions cations use a roman numeral after the name to identify ionic charge Do not memorize o FeCl2 Iron II chloride Polyatomic Ions Composed of more than one atoms Most contain oxygen and another element and their chemical formulas show by subscripts how many of each type if atom are combined Sulfate ion for example is composed of one sulfur atom and four oxygen atoms and has a charge of 2 the ENTIRE GROUP has the charge Ate ending common in oxygen containing One fewer oxygen atom ite Hydrogen atoms connected use hydro or bi bicarbonate hydrocarbonate KNOW NAME FORMULA AND CHARGE RECOGNIZE INSTANTLY Writing formulas Know chage o Charge balance Mg2 NO3 Two nitrates for every magnesium Mg NO3 2 Dissolving Ionic Compounds Na and Cl ions on the surface of NaCl are attracted to water molecules Crystal breaks apart the ions are hydrated in the solution by mant H20 molecules surrounding each ion Physical change Hydronium ions and Hydroxide ions Hydrogen cation is simply a proton Becomes cation When an acid dissolves in water reacts with molecule to form H3O Chemists use hydrogen and hydronium ions interchangeably A hydroxide anion OH is a polyatomic ion which an oxygen atom is covalently bonded to a hydrogen atom