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Chemical Nomenclature Chapters 8-9

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1 Chemical Nomenclature Chapters 8-9

2 Beginning of Class 2/28/13 Get out paper to begin notes for Nomenclature. Label your notes ‘Chemical Formulas’

3 Chemical Formulas 4 naming systems: 1. Naming Acids -H is first element (except water) 2. Naming Organic Compounds -starts with C, contains a few H’s, and maybe a few O’s 3. Naming Binary Ionic Compounds -starts with a metal 4. Naming Binary Molecular Compounds -starts with a nonmetal other than H or C

4 Essential Patterns You must memorize the polyatomic ions!! polyatomic ion: groups of atoms that behave as a unit and possess an overall charge. -if more than one polyatomic is needed, place a parenthesis around it before adding the subscript Pattern 1: The –ate form of polyatomics have 1 more O than the –ite form, but the charge does not change. ~prefix hypo- means 1 less O than the –ite form. ~prefix per- means 1 more O than the –ate.

5 Essential Patterns Pattern 2: The –ates with charges of -2 & -3, can have a H added to form new polyatomic ions. ~H + CO3-2 becomes HCO3-1 (hydrogen carbonate) ~H + PO4-3 becomes HPO4-2 (hydrogen phosphate) ~H + HPO4-2 becomes H2PO4-1 (dihydrogen phosphate) If you keep adding H’s until it becomes neutral, you’ve made an acid!

6 Essential Patterns Pattern 3: Remember your periodic trend for oxidation numbers. ~group 1 metals have a +1 charge ~group 2 metals have a +2 charge ~group 17 nonmetals have a -1 charge ~group 16 nonmetals have a -2 charge ~group 15 nonmetals have a -3 charge ~group 3-15 metals have varying oxidation states, except Ag+1, Zn+2 and Al+3 (know these!!)

7 Naming Acids (We will talk more about acids in Ch 19) There are two types of acids: 1. binary acid: contains hydrogen and one other element -when naming use the prefix hydro- plus the root of the second element with the suffix –ic, followed by the word acid. -ex: HCl H = hydro- Cl = chloride = chloric hydrochloric acid

8 Some acids are not binary, but are named according to the binary acid rules when oxygen is not present, as in HCN. H = hydro CN = cyanide = cyanic hydrocyanic acid 2. oxyacid: an acid that contains an oxyanion (oxygen containing polyatomic ion) -the name depends on the oxyanion present -the name consists of the root of the anion, a suffix, and the word acid ♦if the anion suffix is –ate, it is replaced with -ic ♦if the anion suffix is –ite, it is replaced with -ous

9 -examples: ~HNO3 NO3 = nitrate = nitric nitric acid ~HNO2 NO2 = nitrite = nitrous nitrous acid

10 When writing formulas from the name, the number of H’s depends on the charge of the anion. HNO3 has 1 H because the nitrate ion has a -1 charge. HCl has 1 H because the chloride ion has a -1

11 Beginning of Class 3/4/13 Get out Nomenclature notes.
Find the last notes taken (on oxyacids). Get ready to do practice naming acids, so look over your rules.

12 Naming Acids Practice Name the following acids: HBr H3PO4 H2SO4 H2SO3
Write formulas for: iodic acid hydrophosphoric acid More Practice: p 250 # 18-22, 28b

13 Naming Organic Molecules
organic compound: compound that contains C, H and sometimes an O. hydrocarbons -only contain C and H -simplest of the organic compounds -covalent molecules classified as: alkanes, alkenes, alkynes, aromatics

14 Alkanes alkane: hydrocarbon containing only C-C single bonds (-ane ending) -saturated hydrocarbon: each carbon contains a maximum of 4 single covalent bonds with other atoms -can be shown as straight chains, branched chains, or cyclic chains -follows the formula: CnH2n+2 example: if n = 1, then C1H2(1)+2 to give CH4

15 Unbranched (Straight Chain) Alkanes
C-C bonds form in a straight line.

16 Naming Unbranched Alkanes
1. Use a prefix for the number of carbons it contains: meth- 1 C hex- 6 C eth- 2 C hept- 7 C prop- 3 C oct- 8 C but- 4 C non- 9 C pent- 5 C dec- 10 C 2. Follow the prefix with the ending, -ane Example: C8H18 is named octane Hint: Hydrogen has nothing to do with the actual naming of the compound, except to help you determine if the C-C bonds are single or multiple

17 Branched Alkanes Derived from a straight-chain alkane by replacing one or more of the H atoms atoms with alkyl groups, groups substitued for one or more H’s 1. a suffix that identifies the parent straight-chain alkane ♦count the number of C atoms in the longest continuous chain 2. a prefix that identifies the branching alkyl group 3. the number of the carbon atom to which it is attached

18 Naming Branched Alkanes Example
1. propane is the parent chain 2. contains two methyl groups ♦when more than one branch of the same kind is shown, use the Greek prefixes (mono-, di-, tri- etc.) 3. Both substituted groups are on the same C, C#2 Put it together: 2,2-dimethylpropane

19 Naming Branched Alkanes Practice
CH3 CH3 CH3CHCH2CHCH2CH3 CH3 CH CH3 CH3 CH3CHCH2CH2CHCH2CHCH3 3. Draw 3,4,5-triethyloctane 4. Draw 2,3,dimethyl-5propyldecane More practice p 705 # 3-4

20 Cyclic Alkanes cycloalkane: alkanes where the carbon atoms are arranged in a ring (cyclic) structure -contain minimum of 3 carbons Use the same rules for naming straight-chain alkanes, but with a few modifications: -the ring is the always the parent chain

21 Naming Cyclic Alkanes 1. Count the number of carbons and name as a
straight-chain alkane 2. Once named, place the prefix, cyclo- in front

22 Naming Cyclic Alkanes Cyclic alkanes, like branched alkanes, can contain substituent groups, with each group attached being numbered with the lowest possible set of numbers ♦ if there is only one substituted group, you do not need to number it

23 Complete practice problems #10-11 on p 708
Naming Cycloalkanes Complete practice problems #10-11 on p 708

24 Properties of Alkanes 1. longer chains generally = higher mp/bp
2. relative unreactive 3. nonpolar 4. immiscible in water 5. readily combust in oxygen

25 Alkenes unsaturated hydrocarbon: contains one or more double or triple bonds between C atoms -does not have a maximum number of H alkene: has at least one double bond between carbon atoms -minimum of 2 C’s -alkenes with one double bond have twice as many hydrogens as carbons, as shown in the formula CnH2n -look at Table 22-4 on page 711

26 Naming Alkenes Alkenes are named in much the same way as alkanes, except we change the –ane ending to –ene -examples: ethane becomes ethene H2C=CH2 propane becomes propene H2C=CH-CH3 -if there are 4 or more C’s, you must state the location of the double bond using the lowest number possible C=C-C-C is 1-butene (not 3-butene) C-C=C-C is 2-butene

27 Naming Cyclic Alkenes When you name cyclic alkenes, carbon number 1 must be attached to the double bond -example: cyclopentene (not 1-cyclopentene, since the 1 is assumed) -example: 1,3-dimethylcyclopentene What if the alkene is branched?

28 Naming Branched Alkenes
You name branched alkenes like branched alkanes with 2 differences: -parent chain is always the longest chain that includes the double bond, -the position of the double bond, not the branches, determines how the parent chain is numbered CH3 Example: CH2=C-CH2-CH3 2-methylbutene Lets look at the example on p 713

29 Naming Alkenes Practice
P 716 # 21 b & d

30 More Alkane & Alkene Practice
P # 61-65, 66ab, 67

31 Properties & Uses of Alkenes
1. nonpolar 2. relatively low mp/bp 3. fairly reactive (electron density around double bond) Uses 1. Making plastic bags/jugs (polyethylene) 2. Ripening fruit (ethylene, or ethene-fat soluble hormone) 3. Making rubber (different alkenes) 4. aromatics/scents

32 Alkynes alkyne: contains one or more C-C triple bonds
-must have at least 2 carbons -are named using the same rules as naming alkenes, except with the ending –yne instead of –ene Properties of Alkynes Similar chemical and physical properties as alkenes, though tend to be more reactive because of the high area of electron density on the triple bond -will burn at temp >3000oC when in O2

33 Uses of Alkynes 1. Acetylene (ethyne) torches in welding 2. As a reagent in the manufacture of plastics and other organic industrial chemicals Practice P 716 # 21a, p 733 # 66c

34 Functional Groups Cabron can also bond with atoms other than hydrogen or other carbon compounds -the most common are: O, N, F, Cl, Br, I, S and P functional group: an atom or group of atoms that reacts in a certain way in an organic molecule. •the addition of a functional group produces a compound with different physical and chemical properties than the parent hydrocarbon.

35 Important functional groups:
1. alcohol, -OH -since it is attached to a C, it is NOT a hydroxyl group (hydroxide) 2. phosphate, -PO4 3. sulfhydryl, -SH *functional groups change the shape of a hydrocarbon molecule

36 Naming Ionic Compounds
formula unit: simplest ratio of ions represented in an ionic compound -remember that ionic compounds form a crystal lattice, consisting of many cations and anions. -the overall charge for the compound is 0 Most ionic compounds are binary, consisting of two monatomic ions. -monatomic ion: one atom ion, either positively (cation) or negatively (anion) charged

37 Remember that we determine the charge of each ion by its oxidation number. Formula Rules for Ionic Compounds 1. write the cation first, followed by the anion 2. state the charges of both ions 3. cross the number for the charge of one ion to become the subscript for the other ion. -subscripts are used to state the number of each atom in the compound

38 Example: Determine the formula for the ionic compound formed when potassium reacts with oxygen. 1. Cation = potassium = K Anion = oxygen = O 2. K+1 O-2 3. K+1 O-2 K2O1 K2O You try: Determine the formula for the ionic compound formed when aluminum reacts with chlorine.

39 Ionic Bonding Practice 1
Write the correct formula for the following pairs of atoms: 1. potassium and iodine 2. magnesium and chloride 3. aluminum and bromide

40 Naming Ionic Compounds
1. cation appears first in the name. 2. anion follows, changing its ending to –ide for single atom ions. Ex: What is the name of MgCl2? magnesium chloride

41 Ionic Compounds Practice 2
Write the formula and the name. 1. Na2S 2. Ga2S3 3. CaSe

42 Ionic Compounds with Polyatomic Ions
Use the same rules as binary ionic compounds. -the cation comes first, followed by the anion -state the charges -cross over the number for the charges Remember: -if you have more than one polyatomic ion, place parenthesis around the polyatomic ion, with the subscript outside the parenthesis.

43 Example: Determine the formula for the ionic compound formed when beryllium reacts with cyanide. 1. Cation = beryllium = Be Anion = cyanide = CN- 2. Be+2 CN-1 3. Be+2 CN-1 Be1(CN)2 Be(CN)2 You try: Determine the formula for the ionic compound formed when ammonium reacts with iodine.

44 Ionic Bonding Practice 3
Write the correct formula for the following pairs of atoms: 1. ammonium and oxygen 2. lithium and nitrate 3. aluminum and hydroxide

45 Naming with Polyatomic Ions
Use the binary ionic rules, however: -do not change the ending of the polyatomic ions, even when they are the second atom. Example: Al2(SO4)3 aluminum sulfate Rule: You must state the charge of all metals not included in groups 1 and 2 because many have multiple charges (except our exceptions)

46 Rules for Transition Metals
*According to the previous rules, FeO and Fe2O3 would both be named iron oxide,even though they are not the same compound* Since many transition metals can have more than one charge, the name must show this. This is done using roman numerals. -FeO is named iron (II) oxide because Fe has a +2 charge -Fe2O3 is named iron (III) oxide because Fe has a +3 charge *The roman numeral states the charge of the metal*

47 Q: How do I know the iron in FeO has a +2 charge
Q: How do I know the iron in FeO has a +2 charge? A: The oxide ion has a –2 charge, so the Fe must have a +2 charge so the compound is overall neutral. Q: How do I know the iron in Fe2O3 has a +3 charge? A: There are three oxide ions with a –2 charge: (3 ions)(-2 charge/ion) = a total of –6 charge Since the overall charge must be neutral, the iron must have a total charge of +6. Therefore: (2 ions)(x charge/ion) = +6 x = +3

48 Ionic Compounds Practice 4
Write the formula given & the name of each compound. 1. FeCl3 2. Zn3P2 3. CuS 4. AuF 5. CuC2H3O2 6. AgHCO3 7. ZnSO4 8. Pb(CO3)2

49 Naming Molecules 1. The first element in the formula is named first, using the entire element name. 2. The second element in the formula is named using the root of the element and adding the suffix –ide. 3. Prefixes are used to indicate the number of atoms of each type that are present in the compound. -exception: 1st element never uses the prefix mono- -drop the final letter of the prefix if element name begins with a vowel.

50 Prefixes you need to know: # atoms prefix 1 mono- 2 di- 3 tri- 4 tetra- 5 penta- 6 hexa- 7 hepta- 8 octa- 9 nona- 10 deca-

51 Naming Binary Molecules-Example
Name the compound P2O5, which is used as a drying and dehydrating agent. 1st atom: P = phosphorus 2nd atom: O = oxygen = oxide There are 2 phosphorus = diphosphorus There are 5 oxygens = pentoxide (drop the –a of penta-) Put it together: diphosphorus pentoxide

52 Naming Binary Molecules Practice
Name the following molecules: 1. CCl4 2. As2O3 3. CO

53 Writing Molecular Formulas
Use the prefixes in the molecule’s name to determine the subscript for each atom in the compound. - phosphorus tribromide P Br 1 (no prefix) 3 (tri) PBr3

54 Writing Formulas Practice
1. oxygen difluoride 2. dinitrogen tetrasulfide 3. phosphorus pentachloride

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