IONIC COMPOUNDS: Names and Formulas

Naming compounds in chemistry is called NOMENCLATURE

There are a few general rules that apply when naming ionic compounds. 1. Most ionic compounds are also called salts. 2. Most ionic compounds exist as solids and many dissolve to form aqueous solutions. 3. An ionic compound is made up of a metal and a nonmetal; metals are located on the left side of the periodic table and nonmetals are on the right side. 4. The cation (positive ion) is written first followed by the anion (negative ion). 5. Before naming compounds, you should first memorize the individual cations and anions.

Nomenclature of ionic compounds There are two types of ionic compounds depending on the cations. Type 1 or “fixed oxidation state” cations – only form one cation Groups IA to IIIA and the elements silver (Ag), zinc (Zn) and cadmium (Cd) form only one type of ion each: – Group IA elements form +1 ions: Li+, Na +, K +, Rb +, Cs + – Group IIA elements form +2 ions: Be +2, Mg +2, Ca +2, Sr +2, Ba +2 – Group IIIA elements form +3 ions: Al +3 – silver ion = Ag +; zinc ion = Zn +2; cadmium ion = Cd +2 Type 2 or “variable oxidation state” cations - can form multiple cations

Monatomic Charges The charge of the individual ions in a salt should add up to zero, the overall charge of the compound. For example NaCl is composed of Na+ ions and Cl- ions. For every one sodium ion you need one chloride ion (+1) + (-1) = 0 Ba 2+ and N 3- : You need 3 (+2 ) Barium ions to cancel out the 2 (-3) nitride ions so the overall charge of the compound is zero. Nomenclature of binary ionic compounds Name the metal then the root of the nonmetal + ide ending:

Binary ionic compound ROOTS SymbolElementRootAnion Symbol Anion Name BrBromineBromBr - Bromide ClChlorineChlorCl - Chloride FFluorineFluorF-F- Fluoride HHydrogenHydrH-H- Hydride IIodineIodI-I- Iodide NNitrogenNitrN -3 Nitride OOxygenOxO -2 Oxide PPhosphorusPhosphP -3 Phosphide SSulfurSulfS -2 Sulfide

Nomenclature of binary ionic compounds NaCl BaCl 2 NaF K2OK2OK2OK2O H2SH2SH2SH2S Mg 3 N 2 Sodium chloride Barium chloride Sodium fluoride Potassium oxide Hydrogen sulfideMagnesium nitride  Notice that the cation is always mentioned first and then the anion.  Notice that the anion always ends in -ide  Notice that the number of elements in the compound is not mentioned in the name. Na 2 O K 2 S MgBr 2 AlN Ba 3 As 2 CaCl 2 AgCl AlH 3 ZnI 2 Li 3 P Name the following ionic compounds:

Nomenclature of binary ionic compounds Na 2 O = sodium oxide K 2 S = potassium sulfide MgBr 2 = magnesium bromide AlN = aluminum nitride Ba 3 As 2 = barium arsenide CaCl 2 = calcium chloride AgCl = silver chloride AlH 3 = aluminum hydride ZnI 2 = zinc iodideLi 3 P = lithium phosphide Answers:

Polyatomic Ions Ions made up of more than one atom are polyatomic ions: The individual ions should add up to the overall charge of the polyatomic ion. What is the charge of Mn in MnO 4 - ? 1 Mn + 4 O = -1 so 1(Mn) + 4 (-2) = -1 so Mn - 8 = -1 so Mn = +7 – only one polyatomic cation: NH4 + which is the ammonium ion – many polyatomic anions: ……next page (I will give you a list to memorize)  Note: the polyatomic ions must be memorized.

Nomenclature of binary ionic compounds Some polyatomic anions that you must know: NO 3 - = nitrateNO 2 - = nitrite SO = sulfateSO 3 2- = sulfite PO 4 3- = phosphatePO 3 3- = phosphite CO 3 2- = carbonate HCO 3 1- = hydrogen carbonate or bicarbonate OH - = hydroxideCN - = cyanide C 2 H 3 O 2 - = acetateC 2 O 4 2- = oxalate

Nomenclature of binary ionic compounds NaHCO 3 K 2 SO 3 MgSO 4 KCN H 2 PO 4 Ca(OH) 2 NH 4 NO 3 Zn(NO 3 ) 2 Li 3 PO 4 HNO 3 Naming salts composed of the polyatomic ions is the same as with the monatomic anions. Metal name then polyatomic name. NaOH sodium hydroxide Ba(NO 3 ) 2 barium nitrate H 2 SO 4 hydrogen sulfate CsNO 2 cesium nitrite Sometimes there is a common name: KHCO 3 potassium hydrogen carbonate or potassium bicarbonate Name the following ionic compounds:

Nomenclature of binary ionic compounds NaHCO 3 = sodium hydrogen carbonate or sodium bicarbonate K 2 SO 3 = potassium sulfite MgSO 4 = magnesium sulfate KCN = potassium cyanide H 2 PO 4 = hydrogen phosphate Ca(OH) 2 = calcium hydroxide NH 4 NO 3 = ammonium nitrate Zn(NO 3 ) 2 = zinc nitrate Li 3 PO 4 = lithium phosphate HNO 3 = hydrogen nitrate Answers:

Present NameSymbolFormer Name AntimonySbStibium CopperCuCuprum GoldAuAurum IronFeFerrum LeadPbPlumbum MercuryHgHydrargyrum PotassiumKKalium SilverAgArgentum SodiumNaNatrium TinSnStannum TungstenWWolfram Early Names of Elements

Nomenclature of binary ionic compounds CuHCO 3 FeSO 3 CuSO 4 Cr(CN) 3 Cr(PO 4 ) 2 Sn(OH) 2 W(NO 2 ) 5 Ti(CO 3 ) 2 CoPO 4 PbCl 2 The previous examples only named type 1 or “fixed oxidation state” cations. When naming type 2 or “variable oxidation state” cations the rules change. CuOH copper(I) hydroxide Fe(NO 3 ) 3 iron(III) nitrate CuSO 4 copper(II) sulfate Sn(NO 2 ) 4 tin(IV) nitrite Sometimes a common name exists: CuOH cuprous hydroxide Fe(NO 3 ) 3 ferric nitrate  When naming type 2 cations, the systematic method (IUPAC) requires the use of roman numerals after the elemental name to represent the oxidation state of the cation. The common name uses the –ic ending for the higher oxidation state and –ous ending for the lower oxidation state. Many times the old latin or greek name is used as the root. Name the following ionic compounds:

Nomenclature of binary ionic compounds CuHCO 3 = copper(I) hydrogen carbonate or cuprous bicarbonate FeSO 3 = iron(II) sulfite or ferrous sulfite CuSO 4 = copper(II) sulfate or cupric sulfate Cr(CN) 3 = chromium(III) cyanide Cr(PO 4 ) 2 = chromium (VI) phosphate Sn(OH) 2 = tin(II) hydroxide or stannous hydroxide W(NO 2 ) 5 = tungsten(V) nitrite Ti(CO 3 ) 2 = titanium(IV) carbonate CoPO 4 = cobalt(III) phosphate or cobaltic phosphate PbCl 2 = lead(II) chloride or plumbous chloride Answers:

PRACTICE PROBLEMS Below the formula, give the systematic name for the following compounds. If a common name exist, write it below the systematic name. 1. KBr 2. BaO3. Na 2 O 4. CaF 3 5. Cr 2 S 3 6. Ti(NO 3 ) 4 The problem set continues on the next page. potassium bromide Barium oxide Sodium oxide calcium fluoride Chromium (III) sulfide Titanium (IV) nitrate or titanic nitrate

PRACTICE PROBLEMS Below the name, write the formula for the following compounds. Lithium chloride b) Aluminum sulfide e) Copper(II) oxide f) Iron(III) chloride i) Calcium bicarbonate l Potassium nitritePotassium sulfate Ammonium carbonates s)Iron(II) phosphate w) Li + Cl - LiCl Al 3+ S 2- Al 2 S 3 CuO FeCl 3 Ca(HCO 3 ) 2 KNO 2 K 2 SO 4 (NH 4 ) 2 CO 3 Fe 3 (PO 4 ) 2