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CH 5 NOTES Section 5.1 Objectives: #1 ~ Apply ionic charge to writing formulas for ionic compounds. #2 ~ Apply formulas to name ionic compounds. #3 ~ Interpret the information in a chemical formula. Section Focus Transparency What are the names of some useful ionic compounds? Binary Ionic Compounds Contain only two elements, but may contain more than one ion of each element! **Subscripts NaCl AlCl3 Naming: 1. Write the name of the + ion (usually a metal) 2. Write the name of the – ion (usually a nonmetal), but change the ending on the ending to “-ide” Formula Unit: the simplest ratio of ions in an ionic compound Predicting Charge: You can already do this! Oxidation Number: the charge on the ion…See Table 5.1 **When a compound forms, these charges MUST add up to zero! The compound will be NEUTRAL, right? Ex. Mg 2+ and O 2- combine to form MgO Practice Problems: p. 156 Polyatomic Ions : an ion with 2 or more different elements covalently bonded, but with a charge; See Table 5.2 (p. 157) **The charge is associated with the whole ion…the individual atoms do not have charge! **Subscripts Practice Problems: p. 160 Writing Formulas with Polyatomic Ions Examples: Compounds of Transition Elements: Groups 3-12 When naming, you must use Roman Numerals to identify the oxidation number of the metal! Ex. FeCl3 is iron (III) chloride FeCl2 is iron (II) chloride *** Elements in Group 3-12 (like iron) can have multiple oxidation numbers *** As a result, the transition elements can form a wide variety of compounds…with very different properties Zinc, Cadmium and Silver are exceptions! Zinc and Cadmium are always 2+ and Silver is always 1+ Naming and Writing Formulas for Compounds with Transition Elements Practice Problems: p. 163 DEMO: Iron (II and III) Ammonium Sulfate DEMO: Variable Oxidation States HYDRATES DEMO: Copper (II) sulfate pentahydrate CuSO4 ∙ 5H2O Hydrates : Ionic compounds that have water molecules chemically bonded to them. Ex. CuSO4 ∙ 5H2O; Copper (II) sulfate pentahydrate Anhydrous : all the water is removed (with heat) from a compound. (Blue to white in our demo) Hygroscopic : can become a hydrate by absorbing the water vapor in the air. Deliquescent : can take up enough water from the air that the compounds dissolves completely and forms a liquid. DEMO: A Deliquescent Compound, Sodium Hydroxide, NaOH Naming Hydrates: See Table 5.5 for Prefixes Practice Problems, p. 813 #s 18 and 19 Section 5.2 Objectives: #1 ~ Compare the properties of molecular and ionic substances. #2 ~ Distinguish among allotropes of an element. #3 ~ Apply formulas to name molecular compounds. Section Focus Transparency What are some names of useful molecular substances? Molecular Substances: have atoms held together by covalent bonds General Properties: lower melting points; less soluble in water; not electrolytic; not as hard as ionic compounds Distillation : process which uses the differences between ionic and covalent compounds to separate them from one another…remember the apparatus? (p. 171) Molecular Elements: when atoms of the same elements bond together to form a molecule…NOT compounds Diatomic Elements: What are the 7? How do they bond? Allotropes: molecules made up of a single type of element that differ in their molecular structure. O2 (oxygen) and O3(ozone); Graphite, Coal, Diamonds (all carbon) Hole in the Ozone Organic v. Inorganic Compounds: Naming Molecular Binary Inorganic Compounds 1. Write the name of the first nonmetal if it occurs only once a. If the first nonmetal occurs more than once, you must use the appropriate prefix b. Ex. H2O ~ dihydrogen 2. Write the name of second nonmetal and no matter how many times it occurs in the formula, use the appropriate prefix AND change the ending of the nonmetal name to “ide” a. Ex. H2O ~ dihydrogen monoxide Table 5.5 Prefixes (You must know mono- through deca-) Practice problems p. 179 Common Names Acids & Bases: You must know these by heart: HCl hydrochloric acid H2SO4 sulfuric acid HNO3 nitric acid NH3 ammonia Hydrocarbons: organic compounds made up of only hydrogen and carbon Ex. Methane (natural gas) is CH4 Table 5.8, p. 183 has the rest