CHAPTER 9 Chemical Names and Formulas 9.1 Naming Ions Monatomic Ions: a single atom with a positive or negative charge Cation (rules): listed first Anion (rules): ide ending Transition Metals have a varying Charge Naming Ionic Compounds Cu 3 P 2 Writing Formulas Chromium (III) oxide Copper (II) phosphide Cr 2 O 3 Ions of Transition Metals The charges of the cations of many transition metal ions must be determined from the number of electrons lost. You must memorize the transition metals that form variable charges. Cu, Fe, Sn, Cr, Mn, Hg, Pb, Co, Au Ions of Transition Metals However, all transition metals do not have variable charges. If they can become pseudo stable, they usually have one charge only. Zn 2+, Cd 2+, Ag + Naming Transition Metals When these have a variable charge, the Stock system or common name system is used. Variable charges exist for certain transition metals that lose a varying number of electrons. 1
Stock System Transition metals with variable charge. Roman numerals identify the charge. Cu + = Copper (I), Cu 2+ = Copper (II) Pb 2+ = Lead (II), Pb 4+ = Lead (IV) Fe 2+ = Iron (II), Fe 3+ = Iron (III) Au + = Gold (I), Au 3+ = Gold (III) Common Name System Transition metals with variable charge. Latin name is used for each version. ( ous or ic endings) Cu + = Cuprous, Cu 2+ = Cupric Pb 2+ = Plumbous, Pb 4+ = Plumbic Fe 2+ = Ferrous, Fe 3+ = Ferric Au + = Aurus, Au 3+ = Auric 9.2 Ionic Compounds Naming and Writing Formulas Ionic compounds are composed of positive cations and negative anions. Electrically neutral, meaning the net charge is zero. Formed from metal and nonmetal Binary Ionic Compounds Binary compounds are composed of two elements. The positive charge of the cation must exactly balance the negative charge of the anion Naming Binary Ionic Compounds ide ending Stock System Roman numerals used on an as needed basis 2
4 Big Mistakes in Chapter 9 Nitride Sulfide Phosphide Chloride 1. Don't know charges Nitrite Sulfite Phosphite Chlorite 2. Does it end in... ide, ite, or ate 3. Recognizing metals with variable charges Nitrate Sulfate Phosphate Chlorate 4. Recognizing polyatomic ions Lithium Oxide Chromium (III) bromide Mg 3 P 2 Fe 2 S 3 Polyatomic Ions Polyatomic ions are tightly bound groups of atoms that behave as a unit and carry a charge. ite or ate means oxygen is involved. Polyatomic vs. Monoatomic Must be named differently!!!! Monoatomic anions always end with ide. Polyatomic anions end with ide, ite, or ate. Always look for a polyatomic ion when naming compounds. Compounds with Polyatomic Ions Ionic compounds containing three or more different elements Parentheses used as needed 3
Naming Ionic Compounds Identify the polyatomic ion or monoatomic ion ide, ite, ate Is there a metal with variable charge? (II) (III) (IV) What is the charge? Calcium nitrate Manganese (II) phosphate Al 2 (CO 3 ) 3 Pb(SO 4 ) 2 Variably Charged metal with a polyatomic ion... Cuprous sulfite Cobaltic chromate Mn 2 (CO 3 ) 3 Co 3 (PO 4 ) 2 SnC 2 O 4 Au(ClO 3 ) 3 9.3 Molecular Compounds Naming and Writing Formulas Composed of two nonmetallic elements Ionic charges not used Use table of prefixes ide ending Nonmetals Carbon Silicon Oxygen Chlorine Fluorine Nitrogen Hydrogen Bromine Iodine Selenium Boron Sulfur Phosphorus Arsenic 4
C 2 H 4 S 3 O 6 H 2 O CO CO 2 C 2 H 4 Dicarbon tetrahydride S 3 O 6 Trisulfur hexaoxide H 2 O Dihydrogen monoxide CO Carbon Monoxide CO 2 Carbon dioxide Chemical Naming Rules Is there a polyatomic ion? Yes it is ionic. No go to step 2. Is it metal to nonmetal? Yes it is ionic. No it is molecular. Molecular Formula A molecular formula shows the number and kinds of atoms present in a molecule of a compound. 5
Molecular Compounds Tend to have low melting and boiling points Exist as gases or liquids at room temperature Composed of two or more nonmetals 4 step Naming Process 1. Is there a Polyatomic Ion? (Ionic or Acid) 2. Is there a Metal? (Yes = Ionic) Fixed or Variable charge 3. Is Hydrogen at beginning? (If so, its an acid.) 4. If not an Acid or Ionic... Use prefixes, its molecular Must Memorize for Ch 9. Test 16 Polyatomic Ions 9 metals with variable charge Cr, Mn, Au, Co, Hg, Fe, Cu, Sn, Pb 3 Transition Metals with a fixed charge Zn 2+, Ag +, Ni 2+, Cd 2+ 10 Prefixes used in molecular compounds ous and ic endings Must Memorize for Ch 9. Test 16 Polyatomic Ions 10 Prefixes used in molecular compounds ous and ic endings Acid naming rules When naming Formulas... 1. Ionic (Metal present) 2. Molecular (Nonmetals only) 3. Acids (Begins with hydrogen) exceptions: H 2 O H 2 O 2 (Molecular) 9.4 Naming and Writing Formulas for Acids and Bases Acids are a group of compounds that are given special treatment in naming MEMORIZE!!!! 6
Acids & Bases Acids: compound containing hydrogen atoms producing H + when dissolved in water. Bases: compound producing OH when dissolved in water. Rules for Naming Acids On page 272 Rules for Naming Bases On page 273 Naming Acids: Rule # 1 ide ending (HCl, HF, HBr) Monoatomic anion Hydro (stem) ic HCl: HF: HBr: H 3 P: HCl: Hydro chlor ic HF: Hydro fluor ic HBr: Hydro brom ic H 3 P: Hydor phosphor ic Naming Acids: Rule # 2 Polyatomic anion with ite ending (Sulfite, Nitrite, Phosphite) (stem) ous 7
H 2 SO 3 : HNO 2 : H 3 PO 3 : HClO 2 : H 2 SO 3 : Sulfurous Acid HNO 2 : Nitrous Acid H 3 PO 3 : Phoshorous Acid HClO 2 :Chlorous Acid Naming Acids: Rule # 3 H 2 SO 4 : Polyatomic anion with ate ending (Sulfate, Nitrate, Phosphate) (stem) ic HNO 3 : H 3 PO 4 : HClO 3 : H 2 SO 4 : Sulfur ic acid HNO 3 : Nitr ic acid H 3 PO 4 : Phosphor ic acid HClO 3 :Chlor ic acid Sulfuric Acid Hydrochloric Acid Phosphorous Acid 8
5 Big Mistakes in Chapter 9 1. Charge mistakes, which lead to formula mistakes 2. Does it end in... ide, ite, or ate 3. Metals with variable and fixed charges 4. Recognizing polyatomic ions 5. Using prefixes incorrectly Carbonic Acid Hydrosulfuric Acid Chlorous Acid Acetic Acid 9.5 The Laws Governing Formulas and Names Rule Rule Rule Rule Law of Definite Proportions: 1 compound H 2 CO 3 H 2 S HClO 2 HC 2 H 3 O 2 In samples of any chemical compound, the masses of the elements are always in the same proportions Law of Definite Proportions 50 grams of H 2 O. 100 grams of H 2 O. No matter how much you have, the ratio of hydrogen to oxygen is always the same. The Law of Multiple Proportions When two elements form more than one compound Different masses of one element combine with the same mass of another element. The element with different masses is in the ratio of small whole numbers in their respective compounds. 9
The Law of Multiple Proportions CO: carbon monoxide CO 2 : carbon dioxide Even though you have different amounts of oxygen in each compound, the amount of oxygen is still a whole number. Summary of Naming and Formula Writing In an ionic compound, the net ionic charge is zero 4 step Naming Process 1. Is there a Polyatomic Ion? (Ionic or Acid) 2. Is there a Metal? (Yes = Ionic) Fixed or Variable charge 3. Is Hydrogen at beginning? If so, its an acid. (Except for H 2 O & H 2 O 2 ) 4. All nonmetals, but not and acid. Use prefixes, its molecular An ide ending generally indicates a binary compound An ite or ate ending usually means there is a polyatomic anion in the formula. Most polyatomic ions contain oxygen! Prefixes in the name generally indicate that the compound is molecular. They show the number of each atom in the formula 10