1 Chapter 5 Molecules and Covalent Compounds 5.5 Covalent Compounds and Their Names Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

2 Forming a H 2 Molecule Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

3 H 2, A Covalent Molecule In a hydrogen (H 2 ) molecule Two hydrogen atoms share electrons to form a covalent single bond. Each H atom acquires two (2) electrons. Each H becomes stable like helium (He). Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

4 Diatomic Elements These elements share electrons to form diatomic, covalent molecules. Table 5.9 Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

5 What is the name of each of the following diatomic molecules? H 2______________________ N 2 _______________ Cl 2 _______________ O 2 _______________ I 2 _______________ Learning Check

6 What are the names of each of the following diatomic molecules? H 2 hydrogen N 2 nitrogen Cl 2 chlorine O 2 oxygen I 2 iodine Solution

7 Electron-Dot Formulas Electron-dot formulas show The order of bonded atoms in a covalent compound. The bonding pairs of electrons between atoms. The unshared (lone) valence electrons. A central atom with an octet. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

8 Electron-Dot Formulas and Models of Some Covalent Compounds Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings Table 5.10

9 Names of Covalent Compounds 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 Naming Covalent Compounds STEP 1 Name the first nonmetal as the element. STEP 2 End the name of the second nonmetal with -ide STEP 3 Use prefixes to show the number of atoms (subscripts). Mono is usually omitted. Table 5.11 Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

ON your card Please name the following: N 2 N 2 O N 2 O 4 Please tell me how you feel you are doing this quarter so far 11

Do Now Name the following N 2 O 2 CO CH 4 N 2 O 5 12

13 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

14 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

15 Formulas and Names of Some Covalent Compounds Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings TABLE 4.13

16 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

17 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

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

19 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

20 STEP 1 Write the symbols in the order of the elements in the name. STEP 2 Write any prefixes as subscripts. Example: Write the formula for carbon disulfide. STEP 1 Elements are C and S STEP 2 No prefix for carbon means 1 C Prefix di = 2 Formula: CS 2 Guide to Writing Formulas

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

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

23 Learning Check Identify each compound as ionic or covalent and give its correct name. A. SO 3 B. MnCl 2 C. (NH 4 ) 3 PO 4 D. Cu 2 CO 3 E. N 2 O 4

24 Solution Identify each compound as ionic or covalent and give its correct name. A. SO 3 covalent - sulfur trioxide B. MnCl 2 ionic - manganese(II) chloride C. (NH 4 ) 3 PO 3 ionic - ammonium phosphite D. Cu 2 CO 3 ionic – copper(I) carbonate E. N 2 O 4 covalent – dinitrogen tetroxide

25 Learning Check Identify each compound as ionic or covalent and give its correct name. A. Ca 3 (PO 4 ) 2 B. FeBr 3 C. SCl 2 D. Cl 2 O

26 Solution 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 2 Cl sulfur dichloride D. Cl 2 O covalent 2 Cl 1 O dichlorine oxide