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Classifying Materials Atomic elements = elements whose particles are single atoms. Molecular elements = elements whose particles are multi- atom molecules.

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Presentation on theme: "Classifying Materials Atomic elements = elements whose particles are single atoms. Molecular elements = elements whose particles are multi- atom molecules."— Presentation transcript:

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2 Classifying Materials Atomic elements = elements whose particles are single atoms. Molecular elements = elements whose particles are multi- atom molecules. Molecular compounds = compounds whose particles are molecules made of only nonmetals. Ionic compounds = compounds whose particles are cations and anions.

3 Molecular View of Elements and Compounds

4 Molecular Elements Certain elements occur as 2 atom molecules Rule of 7’s –there are 7 common diatomic elements –find the element with atomic number 7, N –make a figure 7 by going over to Group 7A, then down –don’t forget to include H 2 H2H2 Cl 2 Br 2 I2I2 7 VIIA N 2 O 2 F 2

5 Ionic Compounds Ionic compounds form when metals combine with nonmetals. There are no individual molecules, instead there is a 3-dimensional array made up of formula units of cations and anions. metal atoms form cations, nonmetal atoms for anions Compounds must have no total charge, therefore we must balance the numbers of cations and anions in a compound to get 0 charge If Na + is combined with S 2-, you will need 2 Na + ions for every S 2- ion to balance the charges, therefore the formula must be Na 2 S

6 Molecular Compounds two or more nonmetals smallest unit is a molecule

7 Classify each of the following as either an atomic element, molecular element, molecular compound or ionic compound aluminum, Al aluminum chloride, AlCl 3 chlorine, Cl 2 acetone, C 3 H 6 O carbon monoxide, CO cobalt, Co

8 Classify each of the following as either an atomic element, molecular element, molecular compound or ionic compound aluminum, Al = atomic element aluminum chloride, AlCl 3 = ionic compound chlorine, Cl 2 = molecular element acetone, C 3 H 6 O = molecular compound carbon monoxide, CO = molecular compound cobalt, Co = atomic element

9 Metal Cations Type I –metals whose ions can only have one possible charge IA, IIA, (Al, Ga, In) –determine charge by position on the Periodic Table IA = +1, IIA = +2, (Al, Ga, In = +3) Type II –metals whose ions can have more than one possible charge –determine charge by charge on anion How do you know a metal cation is Type II? It’s not Type I !!!

10 Determine if the following metals are Type I or Type II. If Type I, determine the charge on the cation it forms. lithium, Li copper, Cu gallium, Ga tin, Sn strontium, Sr

11 Determine if the following metals are Type I or Type II. If Type I, determine the charge on the cation it forms. lithium, LiType I+1 copper, CuType II gallium, GaType I+3 tin, SnType II strontium, SrType I+2

12 Type I Binary Ionic Compounds Contain a Metal Cation + a Nonmetal Anion Common simple cations and anions are listed in Table 5.1 The Metal is listed first in the formula & name 1.Name the metal cation first, name the nonmetal anion second. 2.The cation name is the same as the metal name. 3.The nonmetal anion is named by changing the ending on the nonmetal name to –ide

13 Example – Naming Binary Ionic, Type I Metal CsF 1.Identify Major Class Cs = is a metal because it is on the left side of the Periodic Table F = is a nonmetal because it is on the right side of the Periodic Table: Ionic 2.Identify the Subclass 2 elements: Binary Ionic 3.Is the metal Type I or Type II? Cs is in Group IA: Type I 4.Identify the cation and anion Cs = Cs + because it is in Group 1 F = F - because it is in Group 7 5.Name the cation Cs + = cesium 6.Name the anion F - = fluoride 7.Write the cation name first, then the anion name cesium fluoride

14 Type II Binary Ionic Compounds Contain a Metal Cation + a Nonmetal Anion Metal ions are listed first in the formula & name 1.Name the metal cation first, name the nonmetal anion second. 2.Metal cation names are the metal name followed by a Roman Numeral in parentheses to indicate the charge on the cation. –determine charge from the anion charge –Common Type II cations (elements that have more than one possible charge) are listed in Table Nonmetal anions are named by changing the ending on the nonmetal name to -ide

15 Example – Naming Binary Ionic, Type II Metal CuCl 1.Identify Major Class Cu = is a metal because it is on the left side of the PT Cl = is a nonmetal because it is on the right side of the PT  Ionic 2.Identify the Subclass 2 elements,  Binary Ionic 3.Is the metal Type I or Type II Cu is not in Group IA, IIA, or (Al, Ga, In)  Type II 4.Identify cation and anion Cl = Cl - because it is Group 7 Cu = Cu + to balance the charge 5.Name the cation Cu + = copper(I) 6.Name the anion Cl - = chloride 7.Write the cation name first, then the anion name copper(I) chloride

16 Determining the Charge on a Multivalent Cation – Au 2 S 3 1.determine the charge on the anion Au 2 S 3 - the anion is S, since it is in Group 6A, its charge is -2 2.determine the total negative charge since there are 3 S in the formula, the total negative charge is -6 3.determine the total positive charge since the total negative charge is -6, the total positive charge is +6 4.divide by the number of cations since there are 2 Au in the formula & the total positive charge is +6, each Au has a +3 charge

17 Examples: Name the following LiCl AlCl 3 PbO PbO 2 Mn 2 O 3 ZnCl 2 AgCl

18 Examples LiCl = lithium chloride AlCl 3 = aluminum chloride PbO = lead(II) oxide PbO 2 = lead(IV) oxide Mn 2 O 3 = manganese(III) oxide ZnCl 2 = zinc(II) chloride or zinc chloride AgCl = silver(I) chloride or silver chloride

19 Naming Type III Binary Molecular Compounds of 2 Nonmetals 1.Name the first element in the formula first –use the full name of the element 2.Name the second element in the formula with an -ide –as if it were an anion, however, remember these compounds do not contain ions! 3.Use a prefix in front of each name to indicate the number of atoms Never use the prefix mono- on the first element

20 Subscript - Prefixes 1 = mono- –not used on first nonmetal 2 = di- 3 = tri- 4 = tetra- 5 = penta- 6 = hexa- 7 = hepta- 8 = octa- drop the last “a” if the name begins with a vowel Remember these prefixes listed in Table 5.3

21 Example – Naming Binary Molecular BF 3 1.Identify Major Class B = is a nonmetal because it is on the right side of the PT F = is a nonmetal because it is on the right side of the PT  Molecular 2.Identify the Subclass 2 elements:  Binary Molecular 4.Name the first element boron 5.Name the second element with an –ide fluorine  fluoride 6.Add a prefix to each name to indicate the subscript monoboron, trifluoride 7.Write the first element with prefix, then the second element with prefix –Drop prefix mono from first element boron trifluoride

22 Compounds Containing Polyatomic Ions Polyatomic ions are single ions that contain more than one atom. Name these compounds using procedures similar to those for naming binary ionic compounds. Use Table 5.4 to help you recognize these ions until you have memorized them. Note that several polyatomic anions exist that contain an atom of a given element and different numbers of oxygen atoms. These anions are called oxyanions. E.g. oxyanions containing chlorine are: ClO - hypochlorite ClO 2 - chlorite ClO 3 - chlorate ClO 4 - perchlorate

23 Some Common Polyatomic Ions NameFormula acetateC2H3O2–C2H3O2– carbonateCO 3 2– hydrogen carbonate (bicarbonate) HCO 3 – hydroxideOH – nitrateNO 3 – nitriteNO 2 – chromateCrO 4 2– dichromateCr 2 O 7 2– ammoniumNH 4 + NameFormula hypochloriteClO – chloriteClO 2 – chlorate ClO 3 – perchlorateClO 4 – sulfateSO 4 2– sulfiteSO 3 2– Hydrogen sulfate (bisulfate) HSO 4 – Hydrogen sulfite (bisulfite) HSO 3 –

24 Molecules with Polyatomic Ions Mg(NO 3 ) 2 compound called magnesium nitrate symbol of the polyatomic ion called nitrate symbol of the polyatomic ion called sulfate CaSO 4 compound called calcium sulfate implied “1” subscript on magnesium implied “1” subscript on calcium parentheses to group two NO 3 ’sno parentheses for one SO 4

25 Molecules with Polyatomic Ions Mg(NO 3 ) 2 compound called magnesium nitrate CaSO 4 compound called calcium sulfate subscript indicating two NO 3 groups no subscript indicating one SO 4 group implied “1” subscript on nitrogen, total 2 N implied “1” subscript on sulfur, total 1 S stated “3” subscript on oxygen, total 6 O stated “4” subscript on oxygen, total 4 O

26 Example – Naming Ionic Substances when there is a Polyatomic Ion: Na 2 SO 4 Identify Major Class: Na is a metal because it is on the left side of the PT SO 4 2- is a polyatomic ion:  Ionic 2.Identify the Subclass: compound has 3 elements:  Ionic with a Polyatomic Ion 3.Is the metal Type I or Type II? Na is in Group IA: Type I Identify the ions: Na = Na + because it is in Group 1 SO 4 2- = SO 4 2- is a polyatomic ion 5.Name the cation: Na + = sodium ion (Type I) 6.Name the anion: SO 4 2- = sulfate ion 7.Write the name of the cation followed by the name of the anion sodium sulfate

27 Example – Naming Ionic substances with Polyatomic Ion: Fe(NO 3 ) 3 1.Identify Major Class: Fe = is a metal because it is on the left side of the Periodic Table NO 3 1- = is a polyatomic ion: Ionic 2.Identify the Subclass: there are 3 elements:  Ionic with a Polyatomic Ion 3.Is the metal Type I or Type II? Fe is not in Group IA, IIA, or (Al, Ga, In):  Type II 4.Identify the ions: NO 3 = NO 3 - is a polyatomic ion Fe = Fe +3 to balance the charge of the 3 NO Name the cation: Fe +3 = iron(III) ion (Type II) 6.Name the anion: NO 3 - = nitrate ion 7.Write the name of the cation followed by the name of the anion iron(III) nitrate

28 Additional Examples Name the following compounds: PbCO 3 Ca(HCO 3 ) 2 Fe(OH) 2 Cu(NO 3 ) 2 NH 4 I KHSO 4

29 Additional Examples Name the following compounds: PbCO 3 lead(II) carbonate Ca(HCO 3 ) 2 calcium hydrogen carbonate Fe(OH) 2 iron(II) hydroxide Cu(NO 3 ) 2 copper(II) nitrate NH 4 Iammonium iodide KHSO 4 potassium hydrogen sulfate

30 Naming Acids Contain H 3 O +1 cation and an anion in an aqueous solution Binary acids have H 3 O +1 cation and a nonmetal anion Oxyacids have H 3 O +1 cation and a polyatomic anion Acids are molecular compounds that often behave like they are made of ions All names have acid at the end Binary Acids = hydro prefix + stem of the name of the nonmetal + ic suffix See Table 5.5 Oxyacids See Table 5.6 –if the polyatomic ion ends in –ate = name the polyatomic ion with an –ic suffix –if the polyatomic ion ends in –ite = name the polyatomic ion with an –ous suffix

31 Example – Naming Binary Acids HCl 1.Identify Major Class: first element listed is H,  Acid 2.Identify the Subclass: 2 elements,  Binary Acid 3.Identify the anion: Cl = Cl -, chloride because it is in Group 7A 4.Name the anion with an –ic suffix: Cl - = chloride  chloric 4.Add a hydro- prefix to the anion name: hydrochloric 4.Add the word acid to the end: hydrochloric acid

32 Example – Naming Oxyacids H 2 SO 4 1.Identify Major Class: first element listed is H,  Acid 2.Identify the Subclass: 3 elements in the formula,  Oxyacid 3.Identify the anion: SO 4 = SO 4 2- = sulfate If the anion has –ate suffix, change it to –ic. If the anion has –ite suffix, change it to –ous: SO 4 2- = sulfate  sulfuric 4.Write the name of the anion followed by the word acid sulfuric acid

33 Example – Naming Oxyacids H 2 SO 3 1.Identify Major Class: first element listed is H,  Acid 2.Identify the Subclass: 3 elements in the formula,  Oxyacid 3.Identify the anion: SO 3 = SO 3 2- = sulfite 4.If the anion has –ate suffix, change it to –ic. If the anion has –ite suffix, change it to –ous: SO 3 2- = sulfite  sulfurous 4.Write the name of the anion followed by the word acid sulfurous acid

34 Additional Examples Name the following acids: HF H 3 PO 3 HNO 3 HBrO 4 H 2 S

35 Additional Examples Name the following acids: HFhydrofluoric acid H 3 PO 3 phosphorous acid HNO 3 nitric acid HBrO 4 perbromic acid H 2 Shydrosulfuric acid

36 Formula-to-Name Flow Chart

37 Formula-to-Name Step 1 Is the compound one of the exceptions to the rules?

38 Common Names - Exceptions H 2 O = water, steam, ice NH 3 = ammonia CH 4 = methane NaCl = table salt C 12 H 22 O 11 = table sugar

39 Formula-to-Name Step 2 What major class of compound is it? Ionic or Molecular

40 Major Classes Ionic –metal + nonmetal The metal is written first in the formula Binary Ionic –compounds with polyatomic ions Molecular –2 nonmetals Binary Molecular (or Binary Covalent) –Acids – formula starts with H although acids are molecular, they behave as ionic substances when dissolved in water They may be binary or an oxyacid

41 Formula-to-Name Step 3 What major subclass of compound is it? Binary Ionic, Ionic with Polyatomic Ions, Binary Molecular, Binary Acid, Oxyacid

42 Classifying Compounds into major subclasses Compounds containing a metal and a nonmetal = binary ionic –Type I and II Compounds containing two nonmetals = binary molecular compounds –Type III Compounds containing a polyatomic ion = ionic with polyatomic ion Compounds containing H and a nonmetal = binary acids Compounds containing H and a polyatomic ion = oxyacids

43 Formula-to-Name Step 4 Apply Rules for the Class and Subclass

44 Formula-to-Name Rules for Ionic Made of cations and anions Name by simply naming the ions –If the cation is: Type I metal = metal name Type II metal = metal name with the charge written in parentheses as a Roman Numeral Polyatomic ion = name of polyatomic ion –If the anion is: Nonmetal = stem of nonmetal name + ide Polyatomic ion = name of polyatomic ion

45 Monatomic Nonmetal Anion determine the charge from the position on the Periodic Table to name the anion, change the ending on the element name to –ide 4A = -45A = -36A = -27A = -1 C = carbideN = nitrideO = oxideF = fluoride Si = silicideP = phosphideS = sulfideCl = chloride

46 Periodic Pattern of Polyatomic Ions -ate groups BO 3 -3 NO 3 -1 SiO 3 -2 PO 4 -3 SO 4 -2 ClO 3 -1 AsO 4 -3 SeO 4 -2 BrO 3 -1 TeO 4 -2 IO 3 -1 CO 3 -2 IIIA IVA VA VIA VIIA

47 Patterns for Polyatomic Ions -ate ion –chlorate = ClO ate ion + 1 O  same charge, per- prefix –perchlorate = ClO 4 -1 –\–\ -ate ion – 1 O  same charge, -ite suffix –chlorite = ClO ate ion – 2 O  same charge, hypo- prefix, -ite suffix –hypochlorite = ClO -1

48 Practice - What are the formulas for compounds made from the following ions? copper(II) ion with a nitride ion iron(III) ion with a bromide ion aluminum ion with a sulfate ion

49 Cu 2+ with N 3- Cu 3 N 2 Fe +3 with Br - FeBr 3 Al +3 with SO 4 2- Al 2 (SO 4 ) 3

50 Formulas Describe Compounds A compound is a distinct substance that is composed of atoms of two or more elements. Formulas describe a compound by showing the number and type of each atom in the simplest unit of the compound: –molecules or ions: H 2 O, NaCl Each element in a compound formula is represented by the chemical symbol that identifies the element: NaCl, sodium chloride The number of atoms of each element is written to the right of the element as a subscript: –if there is only one atom, the 1 subscript is not written and is understood: CO, carbon monoxide; CO 2, carbon dioxide polyatomic groups are placed in parentheses: –if more than one group is part of the formula the number of groups is written as a subscript:

51 Formulas Describe Compounds Water = H 2 O –  two atoms of hydrogen and 1 atom of oxygen Table sugar = C 12 H 22 O 11 – 12 atoms of C, 22 atoms of H and 11 atoms of O

52 Writing the Formulas from the Names For binary molecular compounds, use the prefixes to determine the subscripts For Type I, Type II, Ternary Compounds and Acids 1.Determine the ions present 2.Determine the charges on the cation and anion 3.Balance the charges to get the subscripts

53 Example – Binary Molecular dinitrogen pentoxide Identify the symbols of the elements nitrogen = N oxide = oxygen = O Write the formula using the prefix “number” for the subscript di = 2, penta = 5 N2O5N2O5

54 Example – Ionic Compounds manganese(IV) sulfide 1.Write the symbol for the cation and its charge 2.Write the symbol for the anion and its charge 3.Charge (without sign) becomes subscript for other ion 4.Reduce subscripts to smallest whole number ratio 5.Check that the total charge of the cations cancels the total charge of the anions Mn +4 S 2- Mn +4 S 2- Mn 2 S 4 Mn = (1)∙(+4) = +4 S = (2)∙(-2) = -4 MnS 2

55 Example – Ionic Compounds Iron(III) phosphate 1.Write the symbol for the cation and its charge 2.Write the symbol for the anion and its charge 3.Charge (without sign) becomes subscript for other ion 4.Reduce subscripts to smallest whole number ratio 5.Check that the total charge of the cations cancels the total charge of the anions Fe +3 PO 4 3- Fe +3 PO 4 3- Fe 3 (PO 4 ) 3 Fe = (1)∙(+3) = +3 PO 4 = (1)∙(-3) = -3 FePO 4

56 Example – Ionic Compounds ammonium carbonate 1.Write the symbol for the cation and its charge 2.Write the symbol for the anion and its charge 3.Charge (without sign) becomes subscript for other ion 4.Reduce subscripts to smallest whole number ratio 5.Check that the total charge of the cations cancels the total charge of the anions NH 4 + CO 3 2- NH 4 + CO 3 2- (NH 4 ) 2 CO 3 NH 4 = (2)∙(+1) = +2 CO 3 = (1)∙(-2) = -2 (NH 4 ) 2 CO 3

57 Example – Binary Acids hydrosulfuric acid 1.Write the symbol for the cation and its charge 2.Write the symbol for the anion and its charge 3.Charge (without sign) becomes subscript for other ion 4.Reduce subscripts to smallest whole number ratio 5.Check that the total charge of the cations cancels the total charge of the anions H+H+ S 2- H + S 2- H2SH2S H = (2)∙(+1) = +2 S = (1)∙(-2) = -2 H2SH2S in all acids the cation is H + hydro means binary

58 Example – Oxyacids carbonic acid 1.Write the symbol for the cation and its charge 2.Write the symbol for the anion and its charge 3.Charge (without sign) becomes subscript for other ion 4.Reduce subscripts to smallest whole number ratio 5.Check that the total charge of the cations cancels the total charge of the anions H+H+ CO 3 2- H + CO 3 2- H 2 CO 3 H = (2)∙(+1) = +2 CO 3 = (1)∙(-2) = -2 H 2 CO 3 in all acids the cation is H + no hydro means polyatomic ion -ic means -ate ion

59 Practice - What are the formulas for the following acids? chlorous acid phosphoric acid hydrobromic acid

60 H + with ClO 2 – HClO 2 H + with PO 4 3– H 3 PO 4 H + with Br – HBr


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