2Beginning of Class 2/28/13Get out paper to begin notes for Nomenclature.Label your notes ‘Chemical Formulas’
3Chemical Formulas4 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
4Essential PatternsYou 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.
5Essential PatternsPattern 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!
6Essential PatternsPattern 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!!)
7Naming 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
8Some 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
10When 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
11Beginning 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.
12Naming Acids Practice Name the following acids: HBr H3PO4 H2SO4 H2SO3 Write formulas for:iodic acidhydrophosphoric acidMore Practice: p 250 # 18-22, 28b
13Naming 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 moleculesclassified as: alkanes, alkenes, alkynes, aromatics
14Alkanesalkane: hydrocarbon containing only C-C single bonds (-ane ending)-saturated hydrocarbon: each carbon contains amaximum of 4 single covalent bonds with otheratoms-can be shown as straight chains, branched chains,or cyclic chains-follows the formula:CnH2n+2example: if n = 1, then C1H2(1)+2to give CH4
15Unbranched (Straight Chain) Alkanes C-C bonds form in a straight line.
16Naming Unbranched Alkanes 1. Use a prefix for the number of carbons it contains:meth- 1 C hex- 6 Ceth- 2 C hept- 7 Cprop- 3 C oct- 8 Cbut- 4 C non- 9 Cpent- 5 C dec- 10 C2. Follow the prefix with the ending, -aneExample: C8H18 is named octaneHint: 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
17Branched AlkanesDerived from a straight-chain alkane by replacing one or more of the H atoms atomswith alkyl groups, groupssubstitued for one or more H’s1. a suffix that identifies the parentstraight-chain alkane♦count the number of C atoms inthe longest continuous chain2. a prefix that identifies thebranching alkyl group3. the number of the carbon atom to which it isattached
18Naming Branched Alkanes Example 1. propane is the parent chain2. 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#2Put it together: 2,2-dimethylpropane
19Naming Branched Alkanes Practice CH3 CH3CH3CHCH2CHCH2CH3CH3CH CH3 CH3CH3CHCH2CH2CHCH2CHCH33. Draw 3,4,5-triethyloctane4. Draw 2,3,dimethyl-5propyldecaneMore practice p 705 # 3-4
20Cyclic Alkanescycloalkane: alkanes where the carbon atoms are arranged in a ring (cyclic) structure-contain minimum of 3 carbonsUse the same rules for naming straight-chain alkanes, but with a few modifications:-the ring is the always the parent chain
21Naming Cyclic Alkanes 1. Count the number of carbons and name as a straight-chain alkane2. Once named, place the prefix, cyclo- in front
22Naming Cyclic AlkanesCyclic 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 notneed to number it
23Complete practice problems #10-11 on p 708 Naming CycloalkanesComplete practice problems #10-11 on p 708
24Properties of Alkanes 1. longer chains generally = higher mp/bp 2. relative unreactive3. nonpolar4. immiscible in water5. readily combust in oxygen
25Alkenesunsaturated hydrocarbon: contains one or more double or triple bonds between C atoms-does not have a maximum number of Halkene: has at least one double bond between carbon atoms-minimum of 2 C’s-alkenes with one double bond have twice as manyhydrogens as carbons, as shown in the formulaCnH2n-look at Table 22-4 on page 711
26Naming AlkenesAlkenes are named in much the same way as alkanes, except we change the –ane ending to –ene-examples: ethane becomes etheneH2C=CH2propane becomes propeneH2C=CH-CH3-if there are 4 or more C’s, you must statethe location of the double bond using the lowestnumber possibleC=C-C-C is 1-butene (not 3-butene)C-C=C-C is 2-butene
27Naming Cyclic AlkenesWhen you name cyclic alkenes, carbon number 1 must be attached to the double bond-example: cyclopentene (not 1-cyclopentene, sincethe 1 is assumed)-example: 1,3-dimethylcyclopenteneWhat if the alkene is branched?
28Naming Branched Alkenes You name branched alkenes like branched alkanes with 2 differences:-parent chain is always the longest chain thatincludes the double bond,-the position of the double bond, not the branches,determines how the parent chain is numberedCH3Example: CH2=C-CH2-CH32-methylbuteneLets look at the example on p 713
30More Alkane & Alkene Practice P # 61-65, 66ab, 67
31Properties & Uses of Alkenes 1. nonpolar2. relatively low mp/bp3. fairly reactive (electron density around double bond)Uses1. Making plastic bags/jugs (polyethylene)2. Ripening fruit (ethylene, or ethene-fat soluble hormone)3. Making rubber (different alkenes)4. aromatics/scents
32Alkynes 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 –eneProperties of AlkynesSimilar 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
33Uses of Alkynes1. Acetylene (ethyne) torches in welding2. As a reagent in the manufacture of plastics andother organic industrial chemicalsPracticeP 716 # 21a, p 733 # 66c
34Functional GroupsCabron can also bond with atoms other than hydrogen or other carbon compounds-the most common are: O, N, F, Cl, Br, I, S and Pfunctional 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 compoundwith different physical and chemical properties than theparent hydrocarbon.
35Important functional groups: 1. alcohol, -OH-since it is attached to a C, it is NOT a hydroxylgroup (hydroxide)2. phosphate, -PO43. sulfhydryl, -SH*functional groups change the shape of a hydrocarbon molecule
36Naming 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
37Remember 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
38Example: 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.
39Ionic 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
40Naming 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
41Ionic Compounds Practice 2 Write the formula and the name.1. Na2S2. Ga2S33. CaSe
42Ionic 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.
43Example: 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.
44Ionic 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
45Naming 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)
46Rules 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*
47Q: 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
48Ionic 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
49Naming Molecules1. 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.
50Prefixes 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-
51Naming 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
52Naming Binary Molecules Practice Name the following molecules: 1. CCl4 2. As2O3 3. CO
53Writing 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