NAMING COVALENT COMPOUNDS

Naming Covalent Compounds Prefixes SubscriptPrefix 1mono- 2di- 3tri- 4tetra- 5penta- SubscriptPrefix 6hexa- 7hepta- 8octa- 9nona- 10deca- Note: When a prefix ending in ‘o’ or ‘a’ is added to ‘oxide’, the final vowel in the prefix is dropped.

Naming Binary Covalent Compounds: Examples N 2 S 4 dinitrogen tetrasulfide NI 3 nitrogen triiodide XeF 6 xenon hexafluoride CCl 4 carbon tetrachloride P 2 O 5 diphosphorus pentoxide SO 3 sulfur trioxide 1mono 2di 3tri 4tetra 5penta 6hexa 7hepta 8octa 9nona 10deca * Drop –a & -o before ‘oxide’

Writing Formulas for Binary Covalent Compounds: Examples nitrogen dioxide NO 2 diphosphorus pentoxide P2O5P2O5 xenon tetrafluoride XeF 4 sulfur hexafluoride SF 6 1mono 2di 3tri 4tetra 5penta 6hexa 7heptaa 8octa 9nona 10deca * Drop –a & -o before ‘oxide’

Naming Compounds: Practice SiF 4 silicon tetrafluoride Na 2 CO 3 sodium carbonate N 2 O dinitrogen monoxide K 2 O potassium oxide Cu 3 PO 4 copper (I) phosphate CoI 3 cobalt (III) iodide AnalysisIf “Yes” * Is the cation a metal? (If so, does it need a Roman numeral? The compound is ionic: name each ion present (DO NOT USE PREFIXES) * Is there a polyatomic ion present? * Are both elements nonmetals? The compound is covalent: use prefixes (NO CHARGES EXIST) PI 3 phosphorus triiodide two nonmetals  covalent  use prefixes metal present  ionic  no prefixes Na  group I  no Roman numeral two nonmetals  covalent  use prefixes metal present  ionic  no prefixes K  group I  no Roman numeral metal present  ionic  no prefixes Cu  not group I, II, etc.  add Roman numeral (PO 4 is 3-, each Cu must be 1+) metal present  ionic  no prefixes Co  not group I, II, etc.  add Roman numeral (I is 1-, total is 3-, Co must be 3+) two nonmetals  covalent  use prefixes NH 4 Cl ammonium chloride NH 4  polyatomic ion present  ionic  no prefixes

Writing Formulas: Practice carbon tetrafluorideCF 4 Na 3 PO 4 sodium phosphate Cu 2 SO 4 copper (I) sulfate AnalysisIf “Yes” The compound is covalent: the prefixes give the subscripts. * Are there prefixes present The compound is ionic: subscripts must be determined by balancing charges prefixes  covalent  prefixes indicate subscripts metal  ionic  balance charges  3 Na 1+ needed for 1 PO 4 3- metal present  ionic  balance charges  2 Cu 1+ needed for 1 SO 4 2- Al 2 S 3 aluminum sulfide metal present  ionic  balance charges  2 Al 3+ needed for 3 S 2- N 2 O 5 dinitrogen pentoxide prefixes  covalent  prefixes indicate subscripts NH 4 NO 3 ammonium nitrate polyatomic ion present  ionic  balance charges  1 NH 4 1+ needed for 1 NO 3 1- PbO 2 lead (IV) oxide metal present  ionic  balance charges  1 Pb 4+ needed for 2 O 2- Fe 2 (CO 3 ) 3 iron (III) carbonate metal present  ionic  balance charges  2 Fe 3+ needed for 3 CO 3 2-