Nomenclature Hint Sheet

Transcription

1 Nomenclature Hint Sheet The nomenclature for four different classes of compounds is covered in CH101: ionic, covalent, acid/base, and organic compounds. This document will cover ionic (chapter 4) and covalent (chapter 5) nomenclature. Acid/base (chapter 12) and organic (chapter 13) nomenclature will be added to this document as we encounter them in the semester (I hope). Ionic Nomenclature They key to naming ionic compounds is understanding that there is no need to specify how many of each type of atom. One must simply define the oxidation state of an ion, if the oxidation state is unclear. The number of each type of ion is then inferred from the number of cations and anions required to make a neutral compounds. There are three sub-types of ionic compounds: main group metal-non-metal, transition metal-non-metal, and those that contain polyatomic ions. Main Group Metal Bound to Non-Metal The main group metals include any cation from Group 1A (alkali metals), Group 2A (alkaline earth metals) and aluminum. The oxidation states of these species is clear: Group 1A cations have a +1 charge Group 2A cations have a +2 charge Al has a +3 charge The name of the cation would simply be the name of the atom. The non-metals in such complexes would be anions. Therefore, the name of the nonmetal would simply be the atom name (with some shortening) + IDE. An example is that Cl (chloride) with a negative charge, Cl, becomes chloride. The total name is simply: Main Group Metal + non-metal-ide Examples: Li 2 S is lithium sulfide (It s obvious that it s 2 Li 1+ to 1 S 2-. It has to be to make a neutral compound) Al 2 O 3 is aluminum oxide (It s obvious that it s 2 Al 3+ to 3 O 2-. It has to be to make a neutral compound) CaF 2 is calcium fluoride (It s obvious that it s 1 Ca 2+ to 2 F. It has to be to make a neutral compound) Transition Metal Bound to Non-Metal Transition metals include any ion from the middle of the periodic table or d block. Examples are scandium, zirconium or rhenium ions. Most transition metals have a 2+ Page 1 9/9/03 L.M. Petrovich

2 charge, but not all. Therefore, we have to specify the transition metal oxidation state with a Roman numeral, in order to make it obvious how many anions and cations are in the ionic compound. The name is simply: Transition metal (oxidation state in Roman numerals) + non-metal-ide (There are a few transition metals that are considered to have only one oxidation state: Ag 1+, Zn 2+ and Cd 2+. These transition metals do not require Roman numerals to specify the oxidation state.) Examples: V 2 S 3 is vanadium(iii) sulfide (Vanadium is a transition metal. Oxidation state unknown. Therefore, we need to specify that it is V 3+ Sulfur is S 2-. It must be V 2 S 3 to make a neutral compound) Naming Polyatomic Ions FeO is iron(ii) oxide (Iron is a transition metal. Oxidation state unknown. Therefore, we need to specify that it is Fe 2+ Oxygen is S 2-. It must be FeO to make a neutral compound) TlF 3 is thallium(iii) fluoride (OK, I know Tl is NOT a transition metal. However, it s oxidation state is still iffy. Therefore, we need to specify that it is Tl 3+ Fluoride is F.) SnCl 4 is tin(iv) chloride (OK, I know Sn is NOT a transition metal. However, it s oxidation state is again iffy. Therefore, we need to specify that it is Sn 4+ Chloride is Cl.) Polyatomic ions are covalently bound atoms with an overall charge on the molecule. There is only one positively charge polyatomic(pa) ion in CH101: NH 4 1+ = ammonium ion There are many negatively charged polyatomic ions. Some require memorization. Others ions, that are composed of a central atom surrounded by oxygen, have a predictable nomenclature. PA Anions to memorize: C 2 H 3 O 2 = CH 3 COO = acetate ion CN = cyanide ion OH = hydroxide ion MnO 4 = permanganate ion PO 4 3- = phosphate ion Page 2 9/9/03 L.M. Petrovich

3 PA Oxyanions of Groups 4,5, and 6: If the central atom is in the highest oxidation state, the name of the ion is: ATOM NAME + ATE If the central atom is two less than the highest oxidation state, the name of the ion is: ATOM NAME + ITE Example: NO 3 is nitrate ion. (N is in Group 5 on the periodic table, therefore it s highest oxidation state is +5. The oxidation state of N in NO 3 is +5. The N is in it s highest oxidation state. The suffix is therefore ATE ) Example: SO 3 2- is sulfite ion. (S is in Group 6 on the periodic table, therefore it s highest oxidation state is +6. The oxidation state of S in SO 3 2- is +4. The S two less than it s highest oxidation state. The suffix is therefore ITE ) Group 4 Group 5 Group 6 CO 3 2- NO 3 SO 4 2- carbonate nitrate sulfate NO 2 Nitrite SO 3 2- sulfite PA Oxyanions of Group 7: For polyatomic oxyanions of group 7, there are 4 possible oxidation states: , +3, +1. The chart below has the prefixes and suffixes for each oxidation state. Central atom PA ion Oxidation State Naming Convention Name BrO 4 +7 PER + central atom INE + ATE perbromate BrO 3 +5 central atom INE + ATE bromate BrO 2 +3 central atom INE + ITE bromite BrO +1 HYPO + central atom INE + ITE hypobromite Example: IO 3 is the iodate ion. (The I is in oxidation state +5) Example: ClO is hypochlorite ion. (The Cl is in oxidation state +1) Page 3 9/9/03 L.M. Petrovich

4 PA Oxyanions with Hydrogen: When the polyatomic ion has a hydrogen associated with it, simply add the prefix hydrogen to the front of the ion name. Sometimes the prefix bi is used instead of hydrogen. If two hydrogens are present, and the material is still an ion, use the prefix dihydrogen. Example: HSO 4 is the hydrogen sulfate ion or the bisulfate ion. Example: H 2 PO 4 is the dihydrogen phosphate ion. Naming Ionic Compounds with PA Ions Use the rules from the previous section for naming man group metals and transition metals with polyatomic anions or the single polyatomic cation. Example: AlPO 4 is aluminum phosphate. (Al is a main group cation. It s always +3. PO 4 3- is the phosphate ion. It s always 3 charge.) Example: Al(NO 2 ) 3 is aluminum nitrite. (Al is a main group cation. It s always +3. NO 2 is the nitrite ion. It s always 1 charge.) Example: Ti(BrO 3 ) 4 is titanium(iv) bromate. (Ti is a transition metal cation. It s oxidation state has variety. We have to specify that the oxidation state is +4. BrO 3 is the bromate ion. It s always 1 charge. Because there are 4 bromate s at 1 charge, we know the Ti must be +4 in order for the compound to be neutral.) Example: Y 2 (SO 4 ) 3 is yttrium(iii) sulfate. (Y is a transition metal cation. It s oxidation state has variety. We have to specify that the oxidation state is +3. SO 4 2- is the sulfate ion. It s always 2 charge. Because there are 3 sulfate s at 2 charge, we know the two Y must be +3 in order for the compound to be neutral.) Example: (NH 4 ) 2 S is ammonium sulfide. (NH 4 1+ is the ammonium ion. S is a simple non-metal anion of 2 charge. Therefore, it is the sulfide ion.) Page 4 9/9/03 L.M. Petrovich

5 Ionic Naming Exercise Question Formula Name 1 Ni(CN) 2 2 NH 4 Cl 3 KH 2 PO 3 4 FeCO 3 5 SnO 2 6 TiBr 4 7 NaHCO 3 8 Na 2 CO 3 9 Fe(OH) 3 10 Hg 2 Cl 2 11 KClO 2 12 Ni(NO 3 ) 3 13 CuCl 14 MgO 15 NaH Ionic Formula Exercise. Give the empirical formula for each of the following: Question Name Formula 16 Copper(II) oxide 17 Mercury (II) sulfide 18 Potassium oxide 19 Ammonium periodate 20 Aluminum oxide 21 Cadmium phosphate 22 Tin(IV) hydroxide 23 Ammonium phosphate 24 Iron (III) oxide 25 Cobalt(III) carbonate 26 Calcium hydroxide 27 Uranium(VI) fluoride 28 Zinc acetate 29 Silver bromide 30 Calcium phosphate Page 5 9/9/03 L.M. Petrovich

6 Key: 1 Nickel(II) cyanide 2 Ammonium chloride 3 Potassium dihydrogen phosphite 4 Iron(II) carbonate 5 Tin(IV) oxide 6 Titanium(IV) bromide 7 Sodium hydrogen carbonate or sodium bicarbonate 8 Sodium carbonate 9 Iron(III) hydroxide 10 Mercury(I) chloride 11 Potassium chlorite 12 Nickel(III) nitrate 13 Copper(I) chloride 14 Magnesium Oxide 15 Sodium hydride 16 CuO 17 HgS 18 K 2 O 19 NH 4 IO 4 20 Al 2 O 3 21 Cd 3 (PO 4 ) 2 22 Sn(OH) 4 23 (NH 4 ) 3 PO 4 24 Fe 2 O 3 25 Co 2 (CO 3 ) 3 26 Ca(OH) 2 27 UF 6 28 Zn(C 2 H 3 O 2 ) 2 29 AgBr 30 Ca 3 (PO 4 ) 2 Page 6 9/9/03 L.M. Petrovich

7 Covalent Nomenclature Covalent compounds are composed of non-metals. They key to naming covalent compounds is recognizing that since the electrons are being shared, there are many possible molar ratios for the atoms in a covalent compound. One must specify the number of each type of atom using Greek prefixes. The less electronegative atom is always written and named first in a binary pair. If there is only one of the first atom, the prefix mono is not used. Number of Atoms Greek Prefix 1 mono 2 di 3 tri 4 tetra 5 penta 6 hexa 7 hepta 8 octa 9 nona 10 deca Example: CO 2 is carbon dioxide Example: CO is carbon monoxide Example: PF 5 is phosphorus pentafluoride Covalent Naming Exercise Question Formula Name 31 S 2 F CSe 2 33 PCl 3 34 S 4 N 4 35 SO 3 36 AsP 37 PBr 5 38 Cl 2 O 7 39 SCl 2 40 CS 41 NI 3 42 TeBr 2 43 Si 2 Br 6 44 SO 2 45 CF 4 Page 7 9/9/03 L.M. Petrovich

8 Key Question Formula Name 31 S 2 F 10 Disulfur decafluoride 32 CSe 2 Carbon diselenide 33 PCl 3 Phosphorus trichloride 34 S 4 N 4 Tetra sulfur tetra nitride 35 SO 3 Sulfur Trioxide 36 AsP Arsenic phosphide 37 PBr 5 Phosphorus pentabromide 38 Cl 2 O 7 Dichloro heptoxide 39 SCl 2 Sulfur dichloride 40 CS Carbon monosulfide 41 NI 3 Nitrogen triiodide 42 TeBr 2 Tellurium dibromide 43 Si 2 Br 6 Disilicon hexabromide 44 SO 2 Sulfur dioxide 45 CF 4 Carbon tetrafluoride Page 8 9/9/03 L.M. Petrovich

9 Acid Nomenclature Materials with acidic hydrogens will have the hydrogen written first in the molecular formula. They key to naming acids is recognizing and naming the ion from which the acid is derived. The suffix of the ion determines the name of the acid, according to the chart below. Polyatomic ion suffix ide ate ite Acid Name Hydro ic acid ic acid ous acid Example: HBr comes from Br Bromide! Hydrobromic acid Example: H 2 CO 3 comes from CO 3 2- Carbonate! Carbonic acid Example: HNO 2 comes from NO 3 Nitrite! Nitrous acid Acid Naming Exercise Question Formula Name 46 HNO 3 47 HC 2 H 3 O 2 48 HCl 49 H 2 SO 4 50 HClO NH 4 52 HNO 2 53 H 2 S Name Formula 54 perchloric acid 55 ammonia 56 phosphoric acid 57 hydroiodic acid 58 bromous acid 59 chloric acid 60 sulfurous acid Page 9 9/9/03 L.M. Petrovich

10 Acid Naming Exercise Key Question Formula Name 46 HNO 3 nitric Acid 47 HC 2 H 3 O 2 acetic acid 48 HCl hydrochloric Acid 49 H 2 SO 4 sulfuric Acid 50 HClO hypochlorous Acid NH 4 ammonium 52 HNO 2 nitrous Acid 53 H 2 S hydrosulfuric acid Name Formula 54 perchloric acid HClO 4 55 ammonia NH 3 56 phosphoric acid H 3 PO 4 57 hydroiodic acid HI 58 bromous acid HBrO 2 59 chloric acid HClO 3 60 sulfurous acid H 2 SO 3 Page 10 9/9/03 L.M. Petrovich