Binary Covalent Compounds Composed of two nonmetals –can be same or different
Two naming systems Stock system: – learned for ionic compounds – “official” Traditional: – what hear on news – what see on ingredient lists
Both Traditional & Stock LeastLeast electronegative of two elements goes first REMINDER: – electronegativity values in table S
Stock System 1st element must have Roman Numeral Have to figure out oxidation number
Stock System & Oxidation Number N’Tmolecular substances DON’T contain ions use concept of oxidation number for electron bookkeeping –pretend all shared electrons go to atom with higher electronegativity value –oxidation number would be: atom with higher electronegativity value has (-) oxidation number atom with lower electronegativity value is (+)
7 Rules for Oxidation Numbers # for free, uncombined element = 0 Na He O 2 N 2 S 8 Cl 2 P # for monatomic ion = charge on ion2. Fluorine is always -1 3. Ca +2 = +2 Cl -1 = -1 Al +3 = +3 CF 4 1.
Oxygen is nearly always -2 EXCEPT when its: Hydrogen is nearly always +1, except when bonded to a metal-then it’s -14.5. LiH CaH 2 NaH OF 2 O 2 2- -Bonded to fluorine, where O is +2 -In the peroxide ion, where O is -1
The sum of oxidation numbers in a neutral compound is 0 The sum of oxidation numbers in a polyatomic ion = charge of the ion 6.7. H 2 O CO 2 NO SO 3 Sum in SO 4 2- = -2 Sum in NO 3 1- = -1
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