Naming Covalent/ Molecular Compounds

Hydrogen compounds are handled differently and will be looked at first. Nomenclature: 1) Name the hydrogen that appears in the formula. 2) Name the second element that appears in the formula, changing its ending to –ide. (Similar to ionic compounds) Examples: HCl hydrogen chloride HIhydrogen iodide Naming Covalent Compounds

Covalent Bonds use prefixes to indicate the number of atoms involved in the compounds 1= mono6 = hexa 2 = di7= hepta 3 = tri8 = octa 4 = tetra9 = nona 5 = penta10 = deca

RULES 1- The name of the first element does not get changed, only a prefix is added if it is more than one. Ex: Trisulfur tetrafluoride S 3 F 4 2- The second element gets a different ending, as well as a prefix. Ex : phosphorus trichloride PCl 3 (NOT: phosphorus trichlorine)

RULES continued.. 3- If the first element in the compound is single you do not write mono: ex. CO 2 - carbon dioxide (NOT monocarbon dioxide) 4- If the element’s name starts with a vowel, and the prefix ends with a vowel, you can drop the last vowel on the prefix: ex. S 5 O 10 - pentasulfur decoxide (NOT pentasulfur decaoxide)

RULES continued.. 5- Covalent compounds do not get simplified. Name the compound exactly as you see it: Ex. H 2 F 2 = dihydrogen difluoride (NOT hydrogen monofluoride HF)

7 What is the name of SO 3 ? STEP 1 The first nonmetal is S sulfur. STEP 2 The second nonmetal is O, named oxide. STEP 3 The subscript 3 of O is shown as the prefix tri. SO 3 → sulfur trioxide The subscript 1(for S) or mono is understood. Naming Covalent Compounds

8 Name P 4 S 3 STEP 1 The first nonmetal P is phosphorus. STEP 2 The second nonmetal S is sulfide. STEP 3 The subscript 4 of P is shown as tetra. The subscript 3 of O is shown as tri. P 4 S 3 → tetraphosphorus trisulfide Naming Covalent Compounds (Continued)

9 Names of Covalent Compounds Remember Prefixes are used  in the names of covalent compounds  because two nonmetals can form two or more different compounds Examples of compounds of N and O: NO nitrogen oxide NO 2 nitrogen dioxide N 2 O dinitrogen oxide N 2 O 4 dinitrogen tetroxide N 2 O 5 dinitrogen pentoxide

10 Select the correct name for each compound. A.SiCl 4 1) silicon chloride 2) tetrasilicon chloride 3) silicon tetrachloride B. P 2 O 5 1) phosphorus oxide 2) phosphorus pentoxide 3) diphosphorus pentoxide C.Cl 2 O 7 1) dichlorine heptoxide 2) dichlorine oxide 3) chlorine heptoxide Learning Check

11 Select the correct name for each compound. A.SiCl 4 3) silicon tetrachloride B. P 2 O 5 3) diphosphorus pentoxide C.Cl 2 O 7 1) dichlorine heptoxide Solution

12 Write the correct formula for each of the following: A. phosphorus pentachloride B. dinitrogen trioxide C. sulfur hexafluoride Learning Check

13 Write the correct formula for each of the following: A. phosphorus pentachloride 1P penta = 5ClPCl 5 B. dinitrogen trioxide di = 2N tri = 3 O N 2 O 3 C. sulfur hexafluoride 1S hexa = 6FSF 6 Solution

TRY THESE: a)Diphosphorus pentoxide b)Nitrogen monoxide c)Xenon hexafluoride d)Tetrarsenic decoxide

a) SiO 2 b) N 2 S 5 c)P 4 O 10 d)BrCl 6 More Examples

16 Formulas, Names and Uses of Some Covalent Compounds

17 Write the name of each covalent compound. CO_____________________ CO 2 _____________________ PCl 3 _____________________ CCl 4 _____________________ N 2 O_____________________ Learning Check

18 Write the name of each covalent compound. CO carbon monoxide CO 2 carbon dioxide PCl 3 phosphorus trichloride CCl 4 carbon tetrachloride N 2 Odinitrogen oxide Solution

HIhydrogen iodide NF 3 nitrogen trifluoride SO 2 sulfur dioxide N 2 Cl 4 dinitrogen tetrachloride NO 2 nitrogen dioxide N2ON2Odinitrogen monoxide Review of Covalent Compounds

20 Ionic and Covalent Identify each compound as ionic or covalent, and give its correct name. A. SO 2 B. BaCl 2 C. (NH 4 ) 3 PO 4 D. Cu 2 CO 3 E. N 2 O 4

21 Solution Identify each compound as ionic or covalent, and give its correct name. A. SO 2 covalent; sulfur dioxide B. BaCl 2 ionic; barium chloride C. (NH 4 ) 3 PO 4 ionic; ammonium phosphate D. Cu 2 CO 3 ionic; copper(I) carbonate E. N 2 O 4 covalent; dinitrogen tetroxide

22 Learning Check Name the following compounds: A. Ca 3 (PO 4 ) 2 B. FeBr 3 C. SCl 2 D. Cl 2 O

23 Solution Name the following compounds: A. Ca 3 (PO 4 ) 2 ionic Ca 2+, PO 4 3− calcium phosphate B. FeBr 3 ionicFe 3+, Br − iron(III) bromide C. SCl 2 covalent 1S, 2Cl sulfur dichloride D. Cl 2 O covalent 2Cl, 1 O dichlorine oxide

Homework Page 249 Problems: 14, 15, 16 and 17 Page 274 Problems: 93, 94 and 95 (a-c)