Chapter 6 Chemical Names and Formulas Adapted from notes by Stephen Cotton Section 6.1 Introduction to Chemical Bonding Distinguish between ionic and molecular compounds. Define cation and anion and relate them to metal and nonmetal. Molecules and Molecular Compounds Approximately 100+ different elements. Millions of compounds from them. Systematic naming is essential. usually don t make compounds. Monatomic Atoms and ions Atoms are electrically. Same number of and. Ions are atoms, or groups of atoms, with a charge (positive or negative). Gain or lose. Polyatomic Two Types of Compounds 1 Molecular compounds Two or more atoms bond into a molecule. Two Types of Compounds 2 Ionic Compounds and bond into a formula unit. lost by the cation are gained by the anion. 1
Two Types of Compounds Smallest piece Types of elements State Melting Point Ionic Molecular Section 6.2 Representing Chemical Compounds Distinguish among chemical formulas, molecular formulas, and formula units. Use experimental data to show that a compound obeys the law of definite proportions and the law of multiple proportions. Chemical Formulas Shows the and of atoms in the smallest piece of a substance. Molecular formula- number and kinds of atoms in a covalent compound ( ). CO 2 Chemical Formulas More than one atom? use a subscript (H 2 O) 7 diatomic molecules Remember: 7 diatomics form a 7 Remember: BrINClHOF = Br 2 I 2 N 2 Cl 2 H 2 O 2 F 2 C 6 H 12 O 6 Ionic Compounds Formula unit- simplest whole number ratio of ions in an ionic compound ( ). NaCl CaCl 2 NH 4 NO 3 Laws: 1. Law of Definite Proportions- the of elements are always in the same proportions. Ex: CO is always 12.011 : 15.9994 Or: 12.011/15.9994 = 0.75071g C to 1.0000g O. Ex: CO 2 is always 12.011 : 31.9988 Or: 12.011/31.9988 = 0.37536g to 1.0000g O 2
Some Laws: 2. Law of Multiple Proportions- the atoms in a compound are in the ratio of small. Ex: The ratio of oxygen (O) in CO 2 to CO is always 2 : 1 Ex: The ratio of oxygen (O) in H 2 O 2 to H 2 O is always 2 : 1 What is the ratio of carbon (C) in C 6 H 12 O 6 to C 12 H 22 O 11? ANS = 1 : 2 Section 6.3 Ionic Charges Use the periodic table to determine the charge on an ion. Define a polyatomic ion, and give the names and formulas of the most common polyatomic ions. Charges on ions Charge is a. Representative groups of elements all have the same. Use periodic table to determine charge for ions. Ex: Na 1+ =, Sr 2+ =. Naming Transition Metal Ions. metals can form more than one ion charge ex: Pb 4+ and Pb 2+ Stock System Uses a Roman numeral to indicate charge. Cu(I) = Cu 1+, Cu(II) = Cu 2+ Classical System Uses suffixes ous and ic to indicate charge. Cuprous = Cu 1+, Cupric = Cu 2+ Na 1+ Ca 2+ Al 3+ Fe 3+ Fe 2+ Hg 2+ 2 Hg 2+ Sn(II) Sn(IV) Name these 3
Write symbols for these Potassium ion Magnesium ion Copper (II) ion Chromium (VI) ion Barium ion Mercury (I) ion Mercury (II) ion Naming Anions Anions are always one charge Change the element ending to. F 1- = Fluor Cl 1- N 3- Br 1- O 2- Ga 3+ Name these Sulfide Iodide Write symbols for these Phosphide Strontium ion Calcium ion Chloride Polyatomic ions Groups of atoms that are covalently bonded together, but have an overall charge and therefore are considered ions. Learn/Memorize - Table 6.4, p.147 Section 6.4 Ionic Compounds Apply the rules for naming and writing formulas for binary ionic compounds. Apply the rules for naming and writing formulas for ternary ionic compounds. 4
Naming Binary Ionic Compounds 2 ions in an compound. Name the two ions to name compound. NaCl = Na 1+ Cl 1- = MgBr 2 = Mg 2+ Br 1- = CuCl 2 = Cu 2+ Cl 1- = NO PREFIXES!!! Naming Binary Ionic Compounds Name the following: KCl CuO Fe 2 O 3 Na 3 N CrN Ternary Ionic Compounds Have polyatomic ions in compound At least three elements Name the to name the compound Ternary Ionic Compounds Name the following: LiCN Fe(OH) 3 (NH 4 ) 2 CO 3 NiPO 4 NaNO 3 Writing Formulas Charges must add up to. Cations from periodic table (except for NH 41 +) Anions from periodic table or polyatomic. Balance charges with. Put polyatomics in. Cation 1 st anion 2 nd Writing Formulas What is the formula for calcium chloride? Charges must cancel out! Criss-Cross Method! 5
Write the formulas for these Lithium sulfide Copper(II) sulfate Iron(III) carbonate Sodium hydrogen carbonate Ammonium nitrate Section 6.5 Molecular Compounds and Acids Apply the rules for naming and writing formulas for binary molecular compounds. Name and write formulas for common acids. Molecular compounds Consist of all Smallest piece is a Don t use charges Name tells you the number of. Use to indicate number. Memorize prefixes T.6.5, pg.159 End ALL molecular names with ide. Exceptions If there is only one of the first element, drop the prefix mono- and just name the element. Exceptions If there is only one of the first element, drop the prefix mono- and just name the element. Example: CO 2 = monocarbon dioxide N 2 O NO 2 Cl 2 O 7 CCl 4 BaCl 2 Name These 6
Write formulas for these diphosphorus pentoxide tetraiodine nonoxide sulfur hexafluoride dinitrogen monoxide aluminum chloride Acids Compounds that produce hydrogen ions (H + ) when dissolved in water. Will have H before the anion.. determines the name. Naming acids If attached to hydrogen ends in -ide, use prefix hydro- and change -ide to -ic acid HCl - hydrogen ion and chloride ion hydrochloric acid H 2 S - hydrogen ion and sulfide ion hydrosulfuric acid Naming Acids If polyatomic anion has, then it ends in -ate or -ite Change -ate to -ic acid (NO PREFIX!!!) HNO 3 hydrogen ion and nitrate ions Nitric acid Change suffix -ite to -ous acid HNO 2 Hydrogen and nitrite ions Nitrous acid HF H 2 SO 4 H 2 SO 3 HCN HCl Name these Writing Acid Formulas Hydrogen will always be first Name tells you the anion Make charges cancel out. 7
Write formulas for these hydroiodic acid acetic acid carbonic acid phosphoric acid phosphorous acid Section 6.6 Summary of Naming and Formula Writing Use the flowchart in Figure 6.21 to write the name of a compound when given its chemical formula progress to no flowchart needed. Use the flowchart in Figure 6.23 to write a chemical formula when given the name of a compound progress to no flowchart needed. Helpful to remember... 1. In an ionic compound, the net ionic charge is (criss-cross method) 2. An ending generally indicates a binary compound 3. An or ending means there is a polyatomic ion that has oxygen 4. generally mean molecular; they show the number of each atom Helpful to remember... 5. A numeral after the name of a cation shows the of the cation and indicates an ionic compound. 8