CHEM 1 GENERAL CHEMISTRY LECTURE HANDOUT

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1 BICOL UNIVERSITY College of Science Department of Chemistry NAMING OF COMPOUNDS CHEM 1 GENERAL CHEMISTRY LECTURE HANDOUT 5 Ver. 1.1 α

2 Covalent or molecular compounds form when elements share electrons in a covalent bond to form molecules. Molecular compounds are electrically neutral. Ionic compounds are (usually) formed when a metal reacts with a nonmetal (or a polyatomic ion). Covalent compounds are formed when two nonmetals react with each other. Since hydrogen is a nonmetal, binary compounds containing hydrogen are also usually covalent compounds. Metal + Nonmetal > ionic compound (usually) Metal + Polyatomic ion > ionic compound (usually) Nonmetal + Nonmetal > covalent compound (usually) Hydrogen + Nonmetal > covalent compound (usually) Predicting Ionic Charges Cation: A positive ion, Mg 2+, NH4 + Anion: A negative ion, Cl -, SO4 2- Group 1 = +1 Group 2 = michaelvmontealegre

3 The cation is given the same name as the neutral metal atom. Ions of Some Main-Group Metals (Groups IA - IIIA) Group Element Cation Ion name IA H H + hydrogen ion Li Li + lithium ion Na Na + sodium ion K K + potassium ion IIA Mg Mg 2+ magnesium ion Ca Ca 2+ calcium ion Sr Sr 2+ strontium ion Ba Ba 2+ barium ion IIIA Al Al 3+ aluminum ion The anion is named by taking the element stem name and adding the ending -ide. Ions of Some Nonmetals (Groups IVA - VIIA) Group Element Anion Ion name VA N N 3- nitride ion P P 3- phosphide ion As As 3- arsenide ion VIA O O 2- oxide ion S S 2- sulfide ion VIA Se Se 2- selenide ion Te Te 2- telluride ion VIIA F F - fluoride ion Cl Cl - chloride ion Br Br - bromide ion IA H H - hydride ion NOMENCLATURE 3

4 Ions of Some Transition Metals and Post-Transition Metals (Groups IVA and VA) Metal Ion Systematic name Common name Cadmium Cd 2+ cadmium ion Chromium Cr 2+ chromium(ii) ion chromous ion Cr 3+ chromium(iii) ion chromic ion Cobalt Co 2+ cobalt(ii) ion cobaltous ion Co 3+ cobalt(iii) ion cobaltic ion Copper Cu + copper(i) ion cuprous ion Cu 2+ copper(ii) ion cupric ion Gold Au 3+ gold(iii) ion Iron Fe 2+ iron(ii) ion ferrous ion Fe 3+ iron(iii) ion ferric ion Manganese Mn2+ manganese(ii) ion manganous ion Mn3+ manganese(iii) ion manganic ion Mercury 2+ Hg 2 mercury(i) ion mercurous ion Hg 2+ mercury(ii) ion mercuric ion Nickel Ni 2+ nickel(ii) ion nickelous ion Ni 3+ nickel(iii) ion nickelic ion Silver Ag + silver ion Zinc Zn 2+ zinc ion Tin Sn 2+ tin(ii) ion stannous ion Sn 4+ tin(iv) ion stannic ion Lead Pb 2+ lead(ii) ion plumbous ion Pb 4+ lead(iv) ion plumbic ion Bismuth Bi 3+ bismuth(iii) ion Bi 5+ bismuth(v) ion 4 michaelvmontealegre

5 Formulas and Names of Some Polyatomic Ions Formula NH 4+ H3O + OH - CN - O2 2- IO3 - N3 - NO2 - NO3 - ClO - ClO2 - ClO3 - ClO4 - - MnO 4 C2H3O2 - C2O4 2- CO3 2- OCN - SCN - S2O3 2- CrO4 2- Cr2O7 2- SO4 2- SO3 2 - PO4 3- HPO H 2 PO 4 HCO3 - HSO4 - HSO3 - Name Ammonium Hydronium Hydroxide Cyanide Peroxide Iodate Azide Nitrite Nitrate Hypochlorite Chlorite Chlorate Perchlorate Permanganate acetate (OAc-) Oxalate Carbonate Cyanate Thiocyanate Thiosulfate Chromate Dichromate Sulfate Sulfite Phosphate hydrogen phosphate (biphosphate) dihydrogen phosphate hydrogen carbonate (bicarbonate) hydrogen sulfate (bisulfate) hydrogen sulfite (bisulfite) NOMENCLATURE 5

6 Some regularities in the names of polyatomic ions. Thio- implies replacing an oxygen atom with a sulfur atom: OCN - cyanate SO4 2- sulfate SCN - thiocyanate S2O3 2- thiosulfate Replacing the first element in the formula with another element from the same group gives a polyatomic ion with the same charge, and a similar name: Group VIIA Group VIA ClO3 - chlorate SO4 2- sulfate BrO3 - bromate SeO4 2- selenate IO3 - iodate TeO4 2- tellurate Group VA* Group IVA 3-2- PO 4 phosphate CO 3 carbonate AsO4 3- arsenate SiO3 2- silicate * But note that nitrogen does not follow this pattern (i.e., nitrate, NO3 - ) Some nonmetals form a series of polyatomic ions with oxygen (all having the same charge): ClO -, hypochlorite; ClO2 -, chlorite; ClO3 -, chlorate; ClO4 -, perchlorate. Formula Name Example XOn y- stem + -ate SO4 2- sulfate XOn-1 y- stem + -ite SO3 2- sulfite XOn-2 y- hypo- + stem + -ite SO2 2- hyposulfite XOn+1 y- per- + stem + -ate SO5 2- persulfate X y- stem + -ide S 2- sulfide 6 michaelvmontealegre

7 1. Write the formulas for the cation and anion, including CHARGES! Example: Barium nitrate Ba 2+ NO3-2. Check to see if charges are balanced. Ba 2+ = +2 NO3 - = (Net charge must be equal to zero not +1) 3. Balance charges, if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Ba 2+ (NO3 - )2 = Ba(NO3)2 1. The cation is written first, followed by the monatomic or polyatomic anion. 2. The subscripts in the formula must produce an electrically neutral formula unit. (That is, the total amount of positive charge must equal the total amount of negative charge.) 3. The subscripts should be the smallest set of whole numbers possible. 4. If there is only one of a polyatomic ion in the formula, do not place parentheses around it; e.g., NaNO3, not Na(NO3). If there is more than one of a polyatomic ion in the formula, put the ion in parentheses, and place the subscript after the parentheses; e.g., Ca(OH)2, Ba3(PO4)2, etc. Examples Cation Anion Formula Na + Cl - NaCl Ca 2+ Br - CaBr2 Na + S 2- Na2S Mg 2+ O 2- MgO Fe 3+ O 2- Fe2O3 Na + SO4 2- Na2SO4 Mg 2+ NO3 - Mg(NO3)2 NH4 + SO4 2- (NH4)2SO4 NOMENCLATURE 7

8 Metals combine with nonmetals to give ionic compounds. When naming binary ionic compounds, name the cation first (specifying the charge, if necessary), then the nonmetal anion (element stem + -ide). Examples NaCl AlBr3 Ca 3 P 2 SrI2 FeCl 2 Sodium chloride Aluminum bromide Calcium phosphide Strontium iodide Iron(II) chloride or ferrous chloride The cation charge must be specified since iron can form more than one charge. Metals combine with polyatomic ions to give ionic compounds. Name the cation first (specifying the charge, if necessary), then the polyatomic ion as listed in the table above (or as derived from the rules which were given) Examples NaOH Ca(NO3)2 (NH4)2SO4 NH4F Mg(C2H3O2)2 Fe(OH)3 Cr3(PO4)2 CrPO4 NaHCO3 Sodium hydroxide Calcium nitrate Ammonium sulfate Ammonium fluoride Magnesium acetate Iron(III) hydroxide or ferrous hydroxide Chromium(II) phosphate Chromium(III) phosphate Sodium hydrogen carbonate or sodium bicarbonate 8 michaelvmontealegre

9 Acids are compounds in which the "cation" is H +. These can be named as compounds as in the previous cases, e.g., HCl is "hydrogen chloride", but are more frequently given special "acid names" (especially when dissolved in water, which is most frequently the case.) The word "hydrogen" is omitted, the word "acid" is added to the end. Compound name -ate Acid name -ic + acid -ite -ide -ous + acid hydro- -ic + acid Examples Example Compound Name Example Acid name HClO3 hydrogen chlorate HClO3(aq) chloric acid H2SO4 hydrogen sulfate H2SO4(aq) sulfuric acid HClO2 hydrogen chlorite HClO2(aq) chlorous acid HCl hydrogen chloride HCl(aq) hydrochloric acid Acid salts are ionic compounds that still contain an acidic hydrogen, such as NaHSO4. In naming these salts, specify the number of acidic hydrogens in the salt. Examples NaHSO4 sodium hydrogen sulfate NaH2PO4 sodium dihydrogen phosphate Na2HPO4 sodium hydrogen phosphate NaHCO3 sodium hydrogen carbonate or sodium bicarbonate The prefix bi- implies an acidic hydrogen: thus, NaHCO3 is sodium bicarbonate (or sodium hydrogen carbonate); NaHSO3 is sodium bisulfite (or sodium hydrogen sulfite), etc. NOMENCLATURE 9

10 The formula is written with the more electropositive element (the one further to the left on the periodic table) placed first, then the more electronegative element (the one further to the right on the periodic table). [Important exception: when the compound contains oxygen and a halogen, the halogen is placed first. If both elements are in the same group, the one with the higher period number is named first.] The first element in the formula is given the neutral element name, and the second one is named by replacing the ending of the neutral element name with -ide. A prefix is used in front of each element name to indicate how many atoms of that element are present: 1 mono- 6 hexa- 2 di- 7 hepta- 3 tri- 8 octa- 4 tetra- 9 nona- 5 penta- 10 deca- If there is only one of the first element in the formula, the mono- prefix is dropped. Examples SO2 sulfur dioxide SO3 sulfur trioxide N2O dinitrogen monoxide NO nitrogen monoxide NO2 nitrogen dioxide N2O4 dinitrogen tetroxide N2O5 dinitrogen pentoxide 10 michaelvmontealegre

11 Complete the following table Name Formula Nitrous acid Ni(IO 3 ) 3 Gold(III) sulfide H 2 SO 3(aq) Nitrogen trifluoride BrI 3 Sodium dichromate S 2 Cl 2 Copper(II) hypochlorite Fe 2 O 3 Potassium nitride NOMENCLATURE 11

12 Book References: Chang, Raymond. Chemistry. 9 th edn. Digital Content Manager Manning, Phillip. Essential Chemistry: Chemical Bonds. Infobase Publishing New York NY, USA Masterton, William L. and Hurley, Cecile N. Chemistry Principles and Reactions 6 th edn. Brooks/Cole Cengage Learning. CA USA Silberberg, Martin S. Chemistry: The molecular nature of matter and change. 5 th edn. The McGraw-Hill Companies, Inc. New York, NY USA Internet Resources: michaelvmontealegre