 Composed of a Cation (+ charge) and an Anion (- charge).  Ionic compounds are electrically neutral.  Ionic compounds are composed of:  A metal and a non-metalNaCl  A metal and a polyatomic anionNaNO 3  A polyatomic cation and a non-metal NH 4 Cl  A polyatomic cation and a polyatomic anionNH 4 NO 3 2

 Metals form cations with + charges.  Group 1 metals form cations with a 1+ charge.  Cations are named with the metal’s name plus ion.  Li 1+ Na 1+ K 1+ Rb 1+ Cs 1+ Fr 1+.  Lithium ion, Sodium ion, Potassium ion, Rubidium ion, Cesium ion, Francium ion. 3

 Group 2 metals form cations with a 2+ charge.  Be 2+ Mg 2+ Ca 2+ Sr 2+ Ba 2+ Ra 2+  Beryllium ion, Magnesium ion, Calcium ion, Strontium ion, Barium ion, Radium ion. 4

 Other metals with only one oxidation state (charge):  Al 3+ Aluminum ion  Zn 2+ Zinc ion  Ag 1+ Silver ion  Cd 2+ Cadmium ion 5

 Transition Metals (Group 3-12) may have more than one oxidation state.  The oxidation state of the transition metal is indicated by a Roman numeral in parenthesis after the metals name (e.g., copper(I) ion is Cu 1+ ).  This is important: Iron(III) DOES NOT mean Fe 3, it means Fe 3+.  Determining the charge on the transition metal means you have to know the names and charges of anions. 6

 Monoatomic anions take the root of the element and add “-ide” (i.e., Cl 1- is chloride, O 2- is oxide).  Halogens (Group 17), when combined with metals, always form a negative 1 charged ion but may form positive oxidation states when combined with oxygen and other non-metals.  Chalcogens (Group 16), when combined with metals, always form a negative 2 charged ion (O 2-, S 2-, Se 2- ).  Group 15, when combined with metals, always form a negative 3 charged ion (N 3-, P 3-, As 3- ).  Group 14, when combined with metals, always form a negative 4 charged ion (C 4-, Si 4- ).  Hydrogen, when combined with metals, always form a negative 1 ion (H 1- ) When combined with non-metals will form a plus 1 ion (H 1+ ). 7

 The ion with the most oxygen atoms takes the suffix –ate following the root of the first element (i.e., nitr ate for NO 3 - ).  The ion with the least oxygen atoms takes the suffix –ite following the root of the first element (i.e., nitr ite for NO 2 - ).  Other examples:  SO 4 2- Sulf ateSO 3 2- Sulf ite  PO 4 3- Phosph ate PO 3 3- P hosph ite 8

 Other important polyatomic oxygen containing ions:  CarbonateCO 3 2-  OxalateC 2 O 4 2-  AcetateC 2 H 3 O 2 1-  ManganateMnO 4 2−  Permanganate MnO 4 1−  ChromateCrO 4 2−  Dichromate Cr 2 O

 The ion with the most oxygen's takes the suffix –ate following the root of the first element (i.e., chlor ate for ClO 3 - ).  The ion with the least oxygen's takes the suffix –ite following the root of the first element (i.e., chlor ite for ClO 2 - ).  The ion with the one more oxygen than the –ate ion takes the prefix per before the root of the first element and the suffix –ate following the root of the first element (i.e., per chlor ate for ClO 4 - ).  The ion with one less oxygen than the –ite ion takes the prefix hypo before the root of the first element and takes the suffix –ite following the root of the first element (i.e., hypo chlor ite for ClO - ). 10

 Diatomic Acids  Halogen containing acids:  These acids are named by adding hydro before the root of the halogen, adding –ic after the root, and adding acid  HF(aq) Hydro fluoric acid  HCl(aq) Hydro chloric acid  HBr(aq) Hydro bromic acid  HI(aq) Hydro iodic acid 11

 The acid with the most oxygen's takes the suffix –ic following the root of the first element (i.e., chlor ic for HClO 3 ) and adding acid. For HClO 3 the name is chlor ic acid.  The acid with the least oxygen's takes the suffix – ous following the root of the first element (i.e., chlor ous for HClO 2 ) and adding acid. For HClO 2 the name is chloro us acid.  The acid with the one more oxygen than the –ic acid takes the prefix per before the root of the first element and the suffix –ic following the root of the first element (i.e., per chlor ic for HClO 4 ) and adding acid. For HClO 4 the name is per chlor ic acid.  The acid with one less oxygen than the –ous acid takes the prefix hypo before the root of the first element and takes the suffix –ous following the root of the first element (i.e., hypo chlor ous for HClO). For HClO the name is hypo chloro us acid. 12

 The acid with the most oxygen's takes the suffix –ic following the root of the first element and adding acid.  Nitrate forms HNO 3 (aq) nitr ic acid  Sulfate forms H 2 SO 4 (aq) sulfur ic acid  Phosphate forms H 3 PO 4 (aq) phosphor ic acid  The acid with the least oxygen's takes the suffix –ous following the root of the first element and adding acid.  Nitrite forms HNO 2 (aq) nitr ous acid  Sulfite forms H 2 SO 3 (aq) sulfur ous acid  Phosphate forms H 3 PO 3 (aq) phosphor ous acid 13

 Carbonate ion forms H 2 CO 3 (aq) Carbonic acid  Oxalate ion forms H 2 C 2 O 4 (aq) Oxalic acid  Acetate ion forms HC 2 H 3 O 2 (aq) Acetic acid 14

 Hydrates are ionic compounds with loosely bound water molecules.  Examples:-  MgSO 4 ·2H 2 O, magnesium sulfate dihydrate  MgSO 4 ·7H 2 O, magnesium sulfate heptahydrate (epsom salts)  Na 2 CO 3 ·10H 2 O, sodium carbonate decahydrate (washing soda). 15

 The number of water molecules is given by Greek prefixes:  Incorrect examples: MgSO 4 -2H 2 O Magnesium diwater Magnesium di(dihydrogen oxide) 16

 Molecular (or covalent) compounds consist of two non metal elements.  Prefixe s are used to indicate the number of atoms.  The less electronegative element is named first in covalent compounds.  The name of the second nonmetal ends in –ide.  Some nonmetals can form more than one compound.  Mono is never used if there is only 1 atom of the first nonmetal. 17

STEP 1 Name the first nonmetal by its element name. STEP 2 Name the second nonmetal with an ide ending. STEP 3 Prefixes to indicate the number (from subscripts) of atoms of each nonmetal. Mono is usually omitted. Name P 4 S 3 STEP 1 The first nonmetal P is phosphorus. STEP 2 The second nonmetal S is sulf ide. STEP 3 The subscript 4 of P is shown as tetra. The subscript 3 of O is shown as tri. P 4 S 3 → tetraphosphorus trisulfide 18

Other Examples: Phosphorus pentachloride: 1P penta = 5Cl PCl 5 Dinitrogen trioxide: di = 2N tri = 3 O N 2 O 3 Xenon tetrafluoride: 1Xe tetra = 4F XeF 4 Write the formula for carbon disulfide. STEP 1 Elements are C and S STEP 2 No prefix for carbon means 1 C Prefix di = 2 means 2 S Formula: CS 2 19

20

Identify each compound as ionic or molecular, and give its correct name: A. SO 2 molecular: 1 S, 2 O sulfur dioxide B. BaCl 2 ionic : Ba 2+, Cl − barium chloride C. N 2 O 4 molecular: 2 N, 4 O dinitrogen tetroxide D. Cu 2 CO 3 ionic: copper(I) carbonate E. Ca 3 (PO 4 ) 2 ionic: Ca 2+, PO 4 3− calcium phosphate F. FeBr 3 ionic: Fe 3+, Br − iron(III) bromide G. SCl 2 molecular: 1 S, 2 Cl sulfur dichloride H. Cl 2 O molecular: 2 Cl, 1 O dichlorine oxide 21