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Chapter Four Nomenclature… TOPICS: 1. Name and write formulas of BINARY compounds of a metals and a nonmetal (Ionic Compounds) 2. Name and Write Formulas for BINARY Compounds containing only nonmetals (Covalent Molecules) 3. Name and write formulas for Ionic Compounds containing polyatomic ions 4. Name and write formulas for acids 1. Name and write formulas of BINARY compounds of a metals and a nonmetal (Ionic Compounds) Writing Formulas: Metal and a nonmetal -Look up charges for each ion using periodic table and/or table of common ions. (note Roman Numeral on + ion corresponds to + charge) -Write each symbol with the charge as a superscript (+ ions always goes first) -Criss-cross charges so that they become subscripts and erase + and – -erase 1’s …not needed -If possible reduce to lowest whole number ratio (not often necessary) examples:p 119 #25 Naming Compounds: metal and a non-metal -positive ion (cation) is named first, take the name of the element, if the cation can have more than one charge use a Roman Numeral to indicate what charge - negative anion (anion) is the first part of element name followed by -ide (example: chloride, oxide, sulfide…etc) examples:p 118 #6,#8 2. Name and Write Formulas for BINARY Compounds containing only non-metals (Covalent Molecules) non-metal and non-metal use prefixes 1 mono (only with 2 di second) 4 tetra 5 penta 7 hepta 8 octa 3 tri 6 hepta Naming Covalent Compounds: -name the first element using the element name -second element is modified with –ide -use prefixes to denote number of atoms present (mono is never used with first element -double vowels are dropped for easier pronunciation examples: p 104 exercise 4.4 and 4.5 Writing Formulas for Covalent Compounds: -use prefixes to denote number of each atom and write as subscript examples: p 119 #26 3. Name and write formulas for Ionic Compounds containing polyatomic ions polyatomic ions : several atoms bound together that exist as an ion. (see table p 109 and handout) These formulas ion cannot be altered, when you need more than one of them you must enclose the formula in ( ) and write a subscript outside on the lower left to indicate how many!!!!! You do not have to memorize these, but the more you use them the more familiar you SHOULD become!!! Writing Formulas: Metal and polyatomic anion or two polyatomic ions -Look up charges for each ion using periodic table and/or table of common polyatomic ions. (note Roman Numeral on + ion corresponds to + charge) -Write each symbol or ions with the charge as a superscript (+ ions always goes first) -Criss-cross charges so that they become subscripts and erase + and – - Use ( ) around polyatomic ion if there is more than one -erase 1’s …not needed -If possible reduce to lowest whole number ratio (not often necessary) examples: p 119 #27 Naming Compounds: Metal and polyatomic anion or two polyatomic ions -positive ion (cation) is named first, take the name of the element, if the cation can have more than one charge use a Roman Numeral to indicate what charge or take name of positive polyatomic cation - negative polyatomic anion name goes second-refer to table!!!! examples:p 111 ex 4.7 4. Name and write formulas for acids acid formulas begin with H - acids are formed when molecules dissolve in water to produce H+ ions - an acid can be viewed as one or more H+ ions attached to a negative ion RULES for naming acids: -When the anion does not contain oxygen use prefix hydro- and suffix – ic attached to root name of anion examples: - When the anion contains oxygen -ate- ion becomes –ic acid -ite ion becomes –ous acid examples: Writing formulas for acids: When writing formulas acids the same rules apply only in reverse and H always comes first with a + 1 charge examples: p 119 # 24,28 In review, writing formulas and naming compounds is easy enough when working with one type….however in the “real world” you have to be able to distinguish what rules apply….so I will ask you Repeatedly 1) is it a metal and a nonmetal (ionic) 2) is it 2 non-metals (molecule-covalently bonded) 3) is it metal and poly anions or 2 polyatomic ions (ionic) 4) does it begin with H….is it an acid