Chapter 9 Chemical Names and Formulas - Troy High School：9章化學名稱和公式-特洛伊高中

1、Unit 4“Chemical Names and FormulasChemistryTroy High SchoolMr. Blake/GowerH2OAtoms and IonsAtoms are electrically neutral.Because there is the same number of protons (+) and electrons (-).Ions are atoms, or groups of atoms, with a charge (positive or negative)They have different numbers of protons a

2、nd electrons.Only electrons can move, and ions are made by gaining or losing electrons.An Anion isA negative ion.Has gained electrons.Nonmetals can gain electrons.Charge is written as a superscript on the right.F1-Has gained one electron (-ide is new ending = fluoride)O2-Gained two electrons (oxide)

3、A Cation isA positive ion.Formed by losing electrons.More protons than electrons.Metals can lose electronsK1+Has lost one electron (no name change for positive ions)Ca2+Has lost two electronsPredicting Ionic ChargesGroup 1A:Lose 1 electron to form 1+ ionsH1+Li1+Na1+K1+Rb1+Predicting Ionic ChargesGro

4、up 2A:Loses 2 electrons to form 2+ ionsBe2+Mg2+Ca2+Sr2+Ba2+Predicting Ionic ChargesGroup 3A: Loses 3 electrons to form 3+ ionsB3+Al3+Ga3+Predicting Ionic ChargesGroup 4A: Do they lose 4 electrons or gain 4 electrons?Neither! Group 4A elements rarely form ions (they tend to share)Predicting Ionic Cha

5、rgesGroup 5A: Gains 3 electrons to form 3- ionsN3-P3-As3-NitridePhosphideArsenidePredicting Ionic ChargesGroup 6A: Gains 2 electrons to form 2- ionsO2-S2-Se2-OxideSulfideSelenidePredicting Ionic ChargesGroup 7A: Gains 1 electron to form 1- ionsF1-Cl1-Br1-FluorideChlorideBromideI1-IodidePredicting Io

6、nic ChargesGroup 8A: Stable noble gases do not form ions!Predicting Ionic ChargesGroup B elements: Many transition elements have more than one possible oxidation state.Iron (II) = Fe2+Iron (III) = Fe3+Note the use of Roman numerals to show chargesNaming CationsTwo methods can clarify when more than

7、one charge is possible:Stock system uses roman numerals in parenthesis to indicate the numerical valueClassical method uses root word with suffixes (-ous, -ic)Does not give true valueNaming cationsWe will use the Stock system.Cation - if the charge is always the same (like in the Group A metals) jus

8、t write the name of the metal.Transition metals can have more than one type of charge.Indicate their charge as a roman numeral in parenthesis after the name of the metal (Table 9.2, p.255)Predicting Ionic Charges Some of the post-transition elements also have more than one possible oxidation state.T

9、in (II) = Sn2+Lead (II) = Pb2+Tin (IV) = Sn4+Lead (IV) = Pb 4+Predicting Ionic ChargesGroup B elements: Some transition elements have only one possible oxidation state, such as these four:Zinc = Zn2+Silver = Ag1+Cadmium = Cd2+Nickel = Ni2+Exceptions:Some of the transition metals have only one ionic

10、charge:Do not need to use roman numerals for these:Silver is always 1+ (Ag1+)Cadmium and Zinc are always 2+ (Cd2+ and Zn2+)Fig. 2.11Practice by naming these:Na+ Ca2+ Al3+ Fe3+ Fe2+ Pb2+ Li+ Sodium IonLead (II) IonAluminum IonIron (III) IonIron (II) IonCalcium IonLithium IonWrite symbols for these:Po

11、tassium ionMagnesium ion Copper (II) ionChromium (II) ionBarium ionMercury (II) ionK+Mg2+Cu2+Cr2+Ba2+Hg2+Naming AnionsAnions are always the same chargeChange the monatomic element ending to ideF1- a Fluorine atom will become a Fluoride ion.Practice by naming these:Cl- N3- Br- O2-Ga3+ChlorideNitrideB

12、romideOxideGallium IonWrite symbols for these:Sulfide ionIodide ionPhosphide ionStrontium ionS2-I-P3-Sr2+Polyatomic ions areGroups of atoms that stay together and have an overall charge, and one name.Usually end in ate or -iteAcetate: C2H3O2-Nitrate: NO3-Nitrite: NO2-Permanganate: MnO4- Hydroxide: O

13、H- and Cyanide: CN-? Sulfate: SO42-Sulfite: SO32-Carbonate: CO32-Chromate: CrO42-Dichromate: Cr2O72-Phosphate: PO43-Phosphite: PO33- Ammonium: NH41+Know Table 9.3 on page 257 and your Ion Sheet!If the polyatomic ion begins with H, then combine the word hydrogen with the other polyatomic ion present:

14、 H1+ + CO32- HCO31- hydrogen + carbonate hydrogen carbonate ion(One of the few positive polyatomic ions)Helpful Hints on Oxy-Anions1. _:smaller # of oxygen2. _:larger # of oxygenEx.NO3-_NO2-_SO42-_SO32-_-ite-ateNitrateNitriteSulfateSulfitehypo-iteClO-_-iteClO2-_ClO3-_ per-ateClO4-_ “_= sulfur replac

15、ing an oxygen.Ex. OCN-_SCN-_SO42-_S2O32-_HypochloriteChloriteChloratePerchlorate-thioCyanateThiocyanateSulfateThiosulfate-ateA Guide to Determine Whether the ate Formula is XO3 or XO4:BCNClBrISiPSAsSe12345612131415161718Transition MetalsA Guide to Determine What the Charge of the Oxy-Anion is:BCNClB

16、rISiPSAsSe12345612131415161718Transition Metals-1-2-3-1-1-1-2-3- 4-2-3Writing Ionic Compound FormulasExample: Barium nitrate (note the 2 word name)1. Write the formulas for the cation and anion, including CHARGES!Ba2+NO3-2. Check to see if charges are balanced. 3. Balance charges , if necessary, usi

17、ng subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross method to balance subscripts.Not balanced!( )2Now balanced.= Ba(NO3)2Writing Ionic Compound FormulasExample: Ammonium sulfate (note the 2 word name)1. Write the formulas for the cation and anion, includ

18、ing CHARGES!NH4+SO42-2. Check to see if charges are balanced. 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross method to balance the subscripts.Not balanced!( )2Now balanced.= (NH4)2SO4Writing Ionic Compound Formu

19、lasExample: Iron (III) chloride (note the 2 word name)1. Write the formulas for the cation and anion, including CHARGES!Fe3+Cl-2. Check to see if charges are balanced. 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cr

20、oss method to balance the subscripts.Not balanced!3Now balanced.= FeCl3Writing Ionic Compound FormulasExample: Aluminum sulfide (note the 2 word name)1. Write the formulas for the cation and anion, including CHARGES!Al3+S2-2. Check to see if charges are balanced. 3. Balance charges , if necessary, u

21、sing subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross method to balance the subscripts.Not balanced!23Now balanced.= Al2S3Writing Ionic Compound FormulasExample: Magnesium carbonate (note the 2 word name)1. Write the formulas for the cation and anion, in

22、cluding CHARGES!Mg2+CO32-2. Check to see if charges are balanced. They are balanced!= MgCO3Writing Ionic Compound FormulasExample: Zinc hydroxide (note the 2 word name)1. Write the formulas for the cation and anion, including CHARGES!Zn2+OH-2. Check to see if charges are balanced. 3. Balance charges

23、 , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross method to balance the subscripts.Not balanced!( )2Now balanced.= Zn(OH)2Writing Ionic Compound FormulasExample: Aluminum phosphate (note the 2 word name)1. Write the formulas for the

24、 cation and anion, including CHARGES!Al3+PO43-2. Check to see if charges are balanced. They ARE balanced!= AlPO4Naming Ionic Compounds1. Name the cation first, then anion2. Monatomic cation = name of the elementCa2+ = calcium ion3. Monatomic anion = root + -ideCl- = chlorideCaCl2 = calcium chlorideN

25、aming Ionic Compoundssome metals can form more than one charge (usually the transition metals)use a Roman numeral in their name:PbCl2 use the anion to find the charge on the cation (chloride is always 1-)Pb2+ is the lead (II) cationPbCl2 = lead (II) chloride(Metals with multiple oxidation states)Thi

26、ngs to look for:If cations have ( ), the number in parenthesis is their charge.If anions end in -ide they are probably off the periodic table (Monoatomic)If anion ends in -ate or ite, then it is polyatomicPractice by writing the formula or name as requiredIron (II) PhosphateStannous FluoridePotassiu

27、m SulfideAmmonium ChromateMgSO4FeCl3Nomenclature of HydratesA. Hydrate: Ionic compound with _ molecules stuck in the _ lattice. The water is included in the _ and formula.Ex. ZnSO4 7 H20: _CaCO3 3 H2O: _Cu2C2O4 2H2O: _Calcium chloride pentahydrate:_watercrystalnameZinc sulfateCalcium carbonateCopper

28、 (I) oxalateCaCl2heptahydratedihydratetrihydrate5H20Molecular compounds aremade of just nonmetalssmallest piece is a moleculecant be held together by opposite charge attractioncant use charges to figure out how many of each atom (there are no charges present)Molecular compounds are easier!Ionic comp

29、ounds use charges to determine how many of each.You have to figure out charges.May need to criss-cross numbers.Molecular compounds: the name tells you the number of atoms.Uses prefixes to tell you the exact number of each element present!Prefixes (Table 9.4, p.269)1 = mono-2 = di-3 = tri-4 = tetra-5

30、 = penta-6 = hexa-7 = hepta-8 = octa- Prefixes9 = nona-10 = deca-To write the name, write two words:One exception is we dont write mono if there is only one of the first element.Normally, we do not have double vowels when writing names (oa oo)PrefixnamePrefixname-idePractice by naming these:N2ONO2 C

31、l2O7 CBr4 CO2 BaCl2 (This one will not use prefixes, since it is an ionic compound!)= dinitrogen monoxide(also called nitrous oxide or laughing gas)= nitrogen dioxide= dichlorine heptoxide= carbon tetrabromide= carbon dioxideWrite formulas for these:diphosphorus pentoxidetetraiodine nonoxidesulfur h

32、exafluoridenitrogen trioxidecarbon tetrahydridephosphorus trifluoridealuminum chloride(Ionic compound)Acids areCompounds that give off hydrogen ions (H1+) when dissolved in water (the Arrhenius definition)Will start the formula with H.There will always be some Hydrogen next to an anion.The anion det

33、ermines the name.Rules for Naming acids: Name it as a normal compound firstIf the anion attached to hydrogen ends in -ide, put the prefix hydro- and change -ide to -ic acidHCl - hydrogen ion and chloride ion = hydrochloric acidH2S hydrogen ion and sulfide ion = hydrosulfuric acidNaming AcidsIf the a

34、nion has oxygen in it, then it ends in -ate or -itechange the suffix -ate to -ic acid (use no prefix)Example: HNO3 Hydrogen and nitrate ions = Nitric acidchange the suffix -ite to -ous acid (use no prefix)Example: HNO2 Hydrogen and nitrite ions = Nitrous acidNaming Acids Normal ending_-ide_-ate_-ite

35、 Acid name ishydro-_-ic acid_-ic acid_-ous acid2 additional rules (not mentioned in the book)If the acid has 1 more oxygen than the ic acid, add the prefix per-HClO3 (Hydrogen Chlorate) is chloric acidHClO4 would be perchloric acidIf there is 1 less oxygen than the -ous acid, add the prefix hypo-HCl

36、O2 (Hydrogen Chlorite) is chlorous acid, then HClO would be hypochlorous acidPractice by naming these:HFH3PH2SO4 H2SO3 HCNH2CrO4 Writing Acid Formulas in reverse!Hydrogen will be listed firstThe name will tell you the anionBe sure the charges cancel out.Starts with prefix hydro?- there is no oxygen,

37、 -ide ending for anionno prefix hydro?-ate anion comes from ic ending-ite anion comes from ous endingWrite formulas for these:hydroiodic acidacetic acidcarbonic acidphosphorous acidhydrobromic acidSummary of Naming and Formula WritingFor naming, follow the flowchart- Figure 9.20, page 277For writing

38、 formulas, follow the flowchart from Figure 9.22, page 278Helpful to remember.1. In an ionic compound, the net ionic charge is zero (criss-cross method)2. An -ide ending generally indicates a binary compound3. An -ite or -ate ending means there is a polyatomic ion that has oxygen4. Prefixes generall

39、y mean molecular; they show the number of each atomCompoundsIonicCovalent (Metal / Non-metal) Binary Ternary Acids Contain H+ Binary Ternary w/ oxygen Hydrates 2 elements -ide Roman numeral (if needed) ie. Calcium chloride CaCl2 3 or more elements Anion is named Roman numerals (if needed) ie. Calciu

40、m carbonate CaCO3 Non-metal / Non-metal Uses prefixes, -ide I2O7 Diiodine heptoxide No oxygen Hydro_ic acid ie, Hydrochloric acid HCl -ateic acid H2CO3 Carbonic acid -ite-ous acid H2SO3Sulfurous acid w/ H2O Uses prefixes ie. Calcium chloride dihydrate CaCl2 2H2OIon Bingo Set 1 (Choose 5 each for your blank sheet and mix them up)Cations (Left side)MgPb (II)LiCaKAlNH4Anions (Top)CO3NO2PO4SBrC2O4ClIon Bingo Set 2 (Choose 5 each for your blank sheet and mix them up)Cations (Left side)Fe (III)