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Ionic compounds contain positive and negative ions. They are held together by electrostatic attraction. Most of the negative ions have only one possible.

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Presentation on theme: "Ionic compounds contain positive and negative ions. They are held together by electrostatic attraction. Most of the negative ions have only one possible."— Presentation transcript:

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2 Ionic compounds contain positive and negative ions. They are held together by electrostatic attraction. Most of the negative ions have only one possible oxidation state. This is not the case with the positive ions. Many of these ions have several oxidation states. The use of prefixes in naming these compounds could lead to confusion. Consequently a new method the stock system is very specific in the naming of ionic compounds.

3 Ionic compounds may contain (1) a metal and a non-metal, (2) a metal and a polyatomic ion or (3) a positive polyatomic ion and a negative polyatomic ion. No matter which is used the procedure for the stock system is the same. The most difficult issue when using the stock system is the memorization of polyatomic ions and their oxidation states. The most common must be committed to memory. Look for trends.... Note location of metals (lower left) and non- metals (upper right) on the periodic chart. Metaloids which border the stair-step transition line may behave as either positive or negative ions.

4 For example the oxy-salts of chlorine, bromine and iodine have many trends in common. Look for them below…… perchlorate ClO 4 -1 chlorate ClO 3 -1 chlorite ClO 2 -1 hypochlorite ClO -1 perbromate BrO 4 -1 bromate BrO 3 -1 bromite BrO 2 -1 hypobromite BrO -1 periodate IO 4 -1 iodate IO 3 -1 iodite IO 2 -1 hypoiodite IO -1 The next table contains the polyatomic ions that need to be committed to memory. Remember to learn the name, formula and oxidation number

5 POLYATOMIC IONS Ions with -1 charge perbromate BrO 4 -1 bromate BrO 3 -1 bromite BrO 2 -1 hypobromite BrO -1 perchlorate ClO 4 -1 chlorate ClO 3 -1 chlorite ClO 2 -1 hypochlorite ClO -1 periodate IO 4 -1 iodate IO 3 -1 iodite IO 2 -1 hypoiodite IO -1 nitrate NO 3 -1 nitrite NO 2 -1 hydroxide OH -1 cyanide CN -1 thiocyanate SCN -1 acetate C 2 H 3 O 2 -1 Permanganate MnO 4 -1 bicarbonate HCO 3 -1 Ions with a -2 Charge carbonate CO 3 -2 phthalate C 8 H 4 O 4 -2 sulfate SO 4 -2 sulfite SO 3 -2 chromate CrO 4 -2 dichromate Cr 2 O 7 -2 oxalate C 2 O 4 -2 peroxide O 2 -2 Ions with a -3 Charge phosphate PO 4 -3 phosphite PO 3 -3 arsenate AsO 4 -3 Ions with +1 charge ammonium ion NH 4 +1

6 POLYATOMIC IONS Ions with -1 charge perbromate BrO 4 -1 bromate BrO 3 -1 bromite BrO 2 -1 hypobromite BrO -1 perchlorate ClO 4 -1 chlorate ClO 3 -1 chlorite ClO 2 -1 hypochlorite ClO -1 periodate IO 4 -1 iodate IO 3 -1 iodite IO 2 -1 hypoiodite IO -1 nitrateNO 3 -1 nitriteNO 2 -1 hydroxideOH -1 cyanideCN -1 thiocyanateSCN -1 acetateC 2 H 3 O 2 -1 PermanganateMnO 4 -1 bicarbonateHCO 3 -1 Ions with a -2 Charge carbonateCO 3 -2 phthalateC 8 H 4 O 4 -2 sulfateSO 4 -2 sulfite SO 3 -2 chromate CrO 4 -2 dichromate Cr 2 O 7 -2 oxalate C 2 O 4 -2 peroxide O 2 -2 Ions with a -3 Charge phosphate PO 4 -3 phosphite PO 3 -3 arsenate AsO 4 -3 Ions with +1 charge ammonium ion NH 4 +1

7 BrO 4 -1 BrO 3 -1 BrO 2 -1 BrO -1 ClO 4 -1 ClO 3 -1 ClO 2 -1 ClO -1 IO 4 -1 IO 3 -1 IO 2 -1 IO -1 Ions with -1 charge perbromate bromate bromite hypobromite perchlorate chlorate chlorite hypochlorite periodate iodate iodite hypoiodite

8 It is also important to memorize the oxidation of the monatomic ions that have fixed oxidation numbers (positive or negative). In particular, those from groups 1A, 2A, 3A, 4A, 5A, 6A, 7A, 8A and the elements: Zn, Cd and Ag. Use the following periodic chart to determine their oxidation numbers. Just click on the element symbol…

9 N Elements with Fixed Oxidation Numbers LaHfTaReOsCeBaTl Pb BiPoAtRnIrPtAuHg YZrNbMoTcRuRbSrInSnSbTeIXeRhPdAgCd ScTiVCrMnFeKCaGaGeAsSeBrKrCoNiCuZn AlSiPSClArNaMg BCOFNeLiBe HHHe AcRfDbSgRhHsFrRaMt A 2A 8A A 6A5A4A3A W NdPmSmEuGdTbCePrYbLuDyHoErTm NpAmCmBkThPaNoLrCfEsFmMdUPu Click on element to see its oxidation number(s) Next Slide

10 Naming Ionic Compounds The positive ion (usually a metal) is named first while the negative ion (a non-metal or a polyatomic ion) is named last. The charge on the negative ion is used to determine the charge on the positive ion. The oxidation state of a compound is always zero, otherwise it would be a polyatomic ion. In-order for the total oxidation state to be zero the total positive charge must equal the total negative charge. A simple algebraic equation can be used to determine the charge on a single metal ion. This charge is expressed as a Roman Numeral in parenthesis that immediately follows the name of the metal. If the positive ion is one that has a fixed oxidation number then no Roman Numeral is used. Everyone should know the charge of that ion. These include metals in group 1A, 2A and the specific metals: Al, Zn, Cd & Ag.

11 If the ionic compound is binary it will end in -ide. However, not all compounds that end in -ide are binary. For example sodium hydroxide has the formula…NaOH (three different kinds of atoms). If the negative ion is a polyatomic ion the compound is no longer binary. The ending will be that carried by the polyatomic ion. These endings are either -ate or -ite. Hydrated compounds are named using a combination of both the stock system and prefixes. A prefix is used to denote the number of water molecules attached to the ionic formula. hydrate is used as the name indicating that water is attached. For example, copper(II) sulfate pentahydrate has the formula CuSO 4. 5H 2 O

12 Examples #1- Formulas to Names CuSO 3 copper Im a polyatomic ion 1.Write the names of the ions Final Name sulfite (II) x X + (- 2) = 0 X = +2 Cu SO 3 = 0 You must know the charge on the sulfite ion is -2 The sum of the positive and negative charges must equal zero 2. Determine the charge of the positive ion Next +2

13 Examples #2- Formulas to Names KMnO 4 potassium Im a polyatomic ion 2.Determine the charge of the positive ion 1.Write the names of the ions Final Name permanganate K x (MnO 4 ) -1 = 0 X + (-1) = 0 (I) X = +1 If the positive ion has a fixed charge, it is not shown

14 Examples #3- Formulas to Names NH 4 NO 3 ammonium Im a polyatomic ion 2.Determine the charge of the positive ion 1.Write the names of the ions Final Name nitrate (I) NH 4 x (NO 3 ) -1 = 0 X + (-1) = 0 X = +1 If the positive ion has a fixed charge, it is not shown

15 Examples #4- Formulas to Names SnF 2 tin Im not a polyatomic ion 2.Determine the charge of the positive ion 1.Write the names of the ions Final Name fluoride (II) Sn x (F -1 ) 2 = 0 X + 2(-1) = 0 X = +2

16 Examples #5- Formulas to Names Ba(ClO 4 ) 2 barium Im a polyatomic ion 2.Determine the charge of the positive ion 1.Write the names of the ions Final Name perchlorate (II) Ba x (ClO 4 -1 ) 2 = 0 X + 2(-1) = 0 X = +2 If the positive ion has a fixed charge, it is not shown

17 Examples #6- Formulas to Names Cu 2 S copper Im not a polyatomic ion 2.Determine the charge of the positive ion 1.Write the names of the ions Final Name sulfide (I) 2Cu x (S) -2 = 0 2X + (-2) = 0 X = +1

18 Examples #6- Formulas to Names Cu 2 S copper 1.Write the names of the ions Final Name sulfide (I) x 2X + (- 2) = 0 2X = +2 (Cu ) 2 S You must know the charge on the sulfide ion is -2 The sum of the positive and negative charges must equal zero 2. Determine the charge of the positive ion Next +1 2 X = +1

19 Examples #7- Formulas to Names Na 2 Cr 2 O 7 sodium Im a polyatomic ion 2.Determine the charge of the positive ion 1.Write the names of the ions Final Name dichromate (I) 2(Na x )(Cr 2 O 7 ) -2 = 0 2X + (-2) = 0 X = +1 If the positive ion has a fixed charge, it is not shown

20 Examples #8- Formulas to Names Na 2 O 2 sodium Im a polyatomic ion 2.Determine the charge of the positive ion 1.Write the names of the ions Final Name peroxide (I) 2(Na x ) (O 2 -2 ) = 0 2X + (-2) = 0 X = +1 If the positive ion has a fixed charge, it is not shown

21 FePO 3. 3H 2 O Examples #9- Formulas to Names iron Im a polyatomic ion 2.Determine the charge of the positive ion 1.Write the names of the ions Final Name phosphite (III) Fe x (PO 3 -3 ) = 0 X + (-3) = 0 X = +3 hydrate Im a hydrated compound, this part will be named last. 3H 2 O 3 tri

22 Examples #10- Formulas to Names LiCN lithium Im a polyatomic ion 2.Determine the charge of the positive ion 1.Write the names of the ions Final Name cyanide (I) Li x (CN -1 ) = 0 X + (-1) = 0 X = +1 If the positive ion has a fixed charge, it is not shown

23 Writing Ionic Formulas It is easier to write the formula of an ionic compound from its name than the reverse. The oxidation state (or charge) of all compounds is zero. This is the first naming system that requires the balancing of the positive and negative charges such that the result is zero. The oxidation number of the negative ion must be memorized in all cases. Refer to the table of polyatomic ions.

24 The positive ion is either one of those that has a fixed oxidation number or a Roman Numeral will follow the positive ion. Metals that have only one oxidation number must be memorized. These include metals in group 1A, 2A and the specific metals: Al, Zn, Cd & Ag. If there is a Roman Numeral is in the name, it represents the charge of one of the positive ions.

25 Remember the total positive charge must equal to the total negative charge. The result is a compound which has no charge. Multiply the oxidation numbers of both the positive and negative ions by a number that will result in the smallest identical numbers of positive and negative charges. These multipliers represent the number of atoms of each ion required to give a neutral ionic compound.

26 The formulas of hydrated compounds are written using a combination of both the stock system and prefixes. A prefix is used to denote the number of water molecules attached to the ionic formula. hydrate is used as the name indicating that water is attached. For example, copper(II) sulfate pentahydrate has the formula CuSO 4. 5H 2 O (notice a dot separates the ionic compound from the water of hydration)

27 Example #1-Names to Formulas aluminum chloride Al Cl 3 2. Determine number of ions 1. Write symbols of elements Final Formula (Al ) x (Cl -1 ) y = 0 3X = 1y X(+3) + y(-1) = 0 Y 3 X 1 = 1 Choose the lowest set of integers that satisfies the equation If there is only one atom the 1 is not shown If there is no Roman Numeral, you need to know the fixed oxidation number of the positive ion. +3 If there is no Roman Numeral, you need to know the fixed oxidation number of the positive ion. What is the Lowest Common Multiple LCM of 3 and 1. Do not worry about the sign(+/-) Next

28 Example #1-Names to Formulas aluminum chloride Al Cl 3 2. Determine number of ions 1. Write symbols of elements Final Formula X(+3) + y(-1) = 0 1 For aluminum, a 1 is multiplied times the +3 to give a +3 charge If there is only one atom the 1 is not shown If there is no Roman Numeral, you must know the oxidation number of the positive ion. +3 If there is no Roman Numeral, you must know the oxidation number of the positive ion. What is the Lowest Common Multiple LCM of 3 and 1. Do not worry about the sign(+/-) (Al ) x (Cl -1 ) y What is the Lowest Common Multiple LCM of 3 and 1. Do not worry about the sign(+/-) For chloride, a 3 is multiplied times the -1 to give a -3 charge 1(+3) + 3(-1) = 0 Remember all compounds are neutral, thus the total positive charge must equal the total negative charge Next This formula says that the +3 charge of one Al atom will cancel the-3 charge from 3 Cl atoms

29 Example #2-Names to Formulas cobalt(II) bromate Co BrO 3 2. Determine number of ions 1. Write symbols of elements Final Formula (Co +2 ) x (BrO 3 -1 ) y = 0 2X = 1y X(+2) + y(-1) = 0 X 1 Y 2 = 1 Choose the lowest set of integers that satisfies the equation (BrO 3 ) 2 If there is only one atom the 1 is not shown Next

30 Example #3-Names to Formulas nickel(III) acetate Ni C2H3O2C2H3O2 2. Determine number of ions 1. Write symbols of elements Final Formula (Ni +3 ) x (C 2 H 3 O 2 -1 ) y = 0 3X = 1y X(+3) + y(-1) = 0 X 1 Y 3 = 1 Choose the lowest set of integers that satisfies the equation (C 2 H 3 O 2 ) 3 If there is only one atom the 1 is not shown Next

31 Example #4-Names to Formulas lithium phosphate Li PO 4 2. Determine number of ions 1. Write symbols of elements Final Formula (Li ) x (PO 4 -3 ) y = 0 1X = 3y X(+1) + y(-3) = 0 X 3 Y 1 = 3 +1 Choose the lowest set of integers that satisfies the equation (PO 4 ) 1 If there is only one atom the 1 is not shown If there is no Roman Numeral, you need to know the fixed oxidation number of the positive ion. Next

32 Practice Problems By now you should have an idea of what is expected when naming covalent binary compounds using prefixes. In order to master this naming system you need to practice until you feel proficient in naming compounds using prefixes.

33 Practice Problem #1 Fe(NO 3 ) 3 Choose the correct name for the compound 1. Iron trinitrate 2. iron(I) nitrate 3. iron(III) nitrite 4. iron(III) nitrate 5. none of the above next problem Polyatomic IonsPeriodic Chart

34 Practice Problem #2 sodium chlorite Choose the correct formula for the compound 1. NaCl 2. NaClO 3. NaClO 2 4. Na(ClO) 2 5. none of the above next problem Prefixes Periodic Chart

35 POLYATOMIC IONS Ions with -1 charge perbromate BrO 4 -1 bromate BrO 3 -1 bromite BrO 2 -1 hypobromite BrO -1 perchlorate ClO 4 -1 chlorate ClO 3 -1 chlorite ClO 2 -1 hypochlorite ClO -1 periodate IO 4 -1 iodate IO 3 -1 iodite IO 2 -1 hypoiodite IO -1 nitrate NO 3 -1 nitrite NO 2 -1 hydroxide OH -1 cyanide CN -1 thiocyanate SCN -1 acetate C 2 H 3 O 2 -1 Permanganate MnO 4 -1 bicarbonate HCO 3 -1 Ions with a -2 Charge carbonate CO 3 -2 phthalate C 8 H 4 O 4 -2 sulfate SO 4 -2 sulfite SO 3 -2 chromate CrO 4 -2 dichromate Cr 2 O 7 -2 oxalate C 2 O 4 -2 peroxide O 2 -2 Ions with a -3 Charge phosphate PO 4 -3 phosphite PO 3 -3 arsenate AsO 4 -3 Ions with +1 charge ammonium ion NH 4 +1 return

36 N Oxidation Numbers (most common) LaHfTaReOsCeBaTl Pb BiPoAtRnIrPtAuHg YZrNbMoTcRuRbSrInSnSbTeIXeRhPdAgCd ScTiVCrMnFeKCaGaGeAsSeBrKrCoNiCuZn AlSiPSClArNaMg BCOFNeLiBe HHHe AcRfDbSgRhHsFrRaMt A 2A 8A A 6A5A4A3A W NdPmSmEuGdTbCePrYbLuDyHoErTm NpAmCmBkThPaNoLrCfEsFmMdUPu Click on element to see its oxidation number(s) return


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