Introductory Chemistry, 3 rd Edition Nivaldo Tro Molecules and Compounds (Part 2) Roy Kennedy Massachusetts Bay Community College Wellesley Hills, MA 2009, Prentice Hall
5.6 Nomenclature: Naming Compounds This will be on quiz 5 2
Formula-to-Name Step 1 Is the compound one of the exceptions to the rules? 3
Common Names Exceptions H 2 O = Water, steam, ice. NH 3 = Ammonia. CH 4 = Methane. NaCl = Table salt. C 12 H 22 O 11 = Table sugar. 4
Formula-to-Name Step 2 What major class of compound is it? Ionic or Molecular? 5
Classifying Ionic or Molecular Ionic compounds. Metal + nonmetal(s) Binary ionic Type I cation charge known Type II cation charge must be given Compounds with polyatomic ions. Molecular compounds. 2 or more nonmetals. Binary molecular (or binary covalent) 2 nonmetals.. Acids Formula starts with H combined with a anion either monoatomic or polyatomic ion. Molecular when pure Ionic when dissolved in water. May be binary or oxyacid. 6
Formula-to-Name Step 3 What major subclass of compound is it? Binary Ionic, Ionic with Polyatomic Ions, Binary Molecular, Binary Acid, or Oxyacid? 7
Classifying Compounds Compounds containing a metal and a nonmetal = Binary ionic. Type I and II. Compounds containing a polyatomic ion = Ionic with polyatomic ion. Compounds containing two nonmetals = Binary molecular compounds. Compounds containing H and a nonmetal = Binary acids. Compounds containing H and a polyatomic ion = Oxyacids. 8
Formula-to-Name Step 4 5.7 Ionic Compounds 5.8 Molecular Compounds 5.9 Acids Molecular compounds that behave like ionic compounds in water 9
5.7 Naming Ionic Compounds 10
Types of Ionic Compounds Monoatomic cation (metal) and monoatomic anion (nonmetal) Cations with only one charge Type I Main group and Ag + and Zn 2+ Cations with more than one charge Type II usually transition metals and some heavier main group elements Polyatomic ion present (KNOW THE POLYATOMIC IONS FROM THE WEB) 11
Formula-to-Name Rules for Ionic Made of cation and anion. Name by simply naming the ions. If cation is: Type I metal = Metal name. Type II metal = Metal name (charge). Polyatomic ion = Name of polyatomic ion. If anion is: Nonmetal = Stem of nonmetal name + -ide. Polyatomic ion = Name of polyatomic ion. 12
Monatomic Nonmetal Anion Charge from periodic table To name anion, take the root of the element name and add the suffix ide. Group 5A Group 6A Group 7A N 3- nitride O 2- oxide F - fluoride P 3- phosphide S 2- sulfide Cl - chloride Br - bromide I - iodide 13
Metal Cations Type I one possible charge. 1A, 2A, (Al, Zn, Ag). Charge by position on the periodic table. 1A = +, 2A = 2+, Al = 3+. Some need to be memorized. Zn = 2+, Ag = +. Type II Metals whose ions can have more than one possible charge. Determine charge by charge on anion. 14
Type I Binary Ionic Compounds Formula Cation name Anion name CaF 2 calcium fluoride K 2 S potassium sulfide NaBr sodium bromide Al 2 S 3 aluminum sulfide MgO magnesium oxide Note: no numerical prefixes are used. 15
Type II Binary Ionic Compounds Cation name (charge as Roman numeral) + anion name Charge is determined from anion 16
Determining the Charge on a Variable Charge Cation NiCl 2 and Fe 2 S 3 1. Ni?+ + 2 Cl - 2. The Ni charge must balance the anions total 2 x (-1) = -2 3. Ni is 2+ nickel(ii)chloride 1. Fe 2 S 3 2Fe?+ + 3 S 2-2. The Fe charge balances the anions. 3 x (-2) = =6 3. Fe is 3+, 2 x (+3) = 6 iron(iii)sulfide 17
Another way to work out the charge Reverse the method of crossing the charges Cu 2 O Cu 2 1+ O 2- copper(i)oxide Be careful because a common factor may have been divided out PbO 2 uncrossing the charges leads to Pb 2+ and O - -, but O is actually O 2-. Two O 2- is -4 This compound is actuall Pb 4+ lead(iv)oxide 18
Compounds Containing Polyatomic Ions Name of cation Type I or Type II rules. + name of anion. 19
The polyatomic ions you need to know are on the stuff you must memorize web page Stuff you must memorize 20
Writing Names for an Ionic Compound Containing Polyatomic Ion, Iron(III) phosphate Type I NaNO 2 sodium nitrite Ca(NO 3 ) 2 calcium nitrate Al 2 (PO 4 ) 3 aluminum phosphate Type II Pb(ClO 4 ) 2 lead(ii)perchlorate 2 ClO 4- means Pb is 2+ CuSO 4 copper (II)sulfate 1 SO 2-4 means Cu is 2+ Fe 2 (PO 4 ) 3 iron(iii) phosphate 2 PO 3-4 means Fe is 3+ 21
5.8 Naming Molecular Compounds 22
Formula-to-Name Rules for Molecular Only for 2 elements binary. For binary molecular: numerical first numerical root Prefix + element + prefix + second + -ide (omit if 1) name element 23
Numerical Prefixes 1 = mono- Not used on first nonmetal. 2 = di- 3 = tri- 4 = tetra- 5 = penta- 6 = hexa- Drop last a if name begins with vowel. 24
Binary Molecular Compounds of Two Nonmetals SO 3 CS 2 S 4 N 4 SF 6 P 2 O 5 sulfur trioxide carbon dioxide tetrasulfur tetranitride sulfur hexafluoride diphosphorus pentaoxide
5.9 Naming Acids 26
Formula-to-Name Acids Acids have formulas that start with H and contain an anion either monoatomic or polyatomic Acids are molecular, but when dissolved in water they for ions H + cation(s) and an anion(s). 27
Binary acids monoatomic ion Hydro- prefix + stem of the name of the nonmetal + -ic suffix + acid. HCl HBr HI hydrochloric acid hydrobromic acid hydroiodic acid 28
Polyatomic ion acid Oxyacids: If polyatomic ion ends in ate = Name of polyatomic ion with ic suffix + acid. If polyatomic ion ends in ite = Name of polyatomic ion with ous suffix + acid. Acid anion name HNO 3 nitrate nitric acid H 2 SO 3 sulfite sulfurous acid HClO 4 perchlorate perchloric acis H 2 CrO 4 chromate chromic acid H 3 PO 4 phosphate phosphoric acid H 3 PO 3 phosphite phosphorus acid 29
Naming compounds from formula Decide if common name Classify as Ionic or Molecular Ionic Type I or II cation Monoatomic or polyatomic ion Molecular Binary Acids Binary Oxyacids 30
Naming examples Ca(ClO 4 ) 2 NH 3 P 4 S 5 HClO 3 Na 2 S CoCl 3 HBr calcium perchlorate ammonia tetraphosphorous pentasulfide chlorous acid sodium sulfide cobalt(iii)chloride hydrobromic acid 31
5.10 Nomenclature Summary An excellent summary of naming compounds is Figure 5.17 on page 143. 32