1 4.6 Covalent Compounds Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings Chapter 4 Forces Between Particles

2 Covalent bonds form when atoms share electrons to complete octets. between two nonmetal atoms. between nonmetal atoms from Groups 4A(14), 5A(15), 6A(16), and 7A(17). Covalent Bonds

3 Hydrogen Molecule A hydrogen molecule is stable with two electrons (helium). has a shared pair of electrons.

4 Forming Octets in Molecules In a fluorine, F 2,, molecule, each F atom shares one electron. attains an octet.

5 Carbon forms 4 covalent bonds In a CH 4, methane, molecule a C atom shares 4 electrons to attain an octet. each H shares 1 electron to become stable like helium.

6 Multiple Bonds In nitrogen molecule, N 2, each N atom shares 3 electrons. each N attains an octet. the bond is a multiple bond called a triple bond. the name is the same as the element.

7 Naming Covalent Compounds To name covalent compounds STEP 1: Name the first nonmetal as an element. STEP 2: Name the second nonmetal with an ide ending. STEP 3: Use prefixes to indicate the number of atoms (subscript) of each element. Table4.12

8 What is the name of SO 3 ? 1. The first nonmetal is S sulfur. 2. The second nonmetal is O named oxide. 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

9 Name P 4 S The first nonmetal P is phosphorus. 2. The second nonmetal S is sulfide. 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

10 Formulas and Names of Some Covalent Compounds Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

11 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 pentaoxide 3) diphosphorus pentaoxide C.Cl 2 O 7 1) dichlorine heptaoxide 2) dichlorine oxide 3) chlorine heptaoxide Learning Check

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

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

14 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 monoxide Solution

15 The prefixes in the name are used to write the formula. 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

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

17 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

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

19 Solution Identify each compound as ionic or covalent and give its correct name. A. SO 3 covalent – sulfur trioxide B. BaCl 2 ionic – barium 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

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

21 Solution Name the following compounds. A. Ca 3 (PO 4 ) 2 ionic Ca 2+ PO 4 3− calcium phosphate B. FeBr 3 ionic Fe 3+ Br − iron(III) bromide C. SCl 2 covalent 1S 2 Cl sulfur dichloride D. Cl 2 O covalent 2 Cl 1 O dichlorine monoxide E. N 2 covalent 2N(element) nitrogen

22 Learning Check Write the formulas for the following. A. calcium nitrate B. boron trifluoride C. aluminum carbonate D. dinitrogen tetroxide E. copper(I) phosphate

23 Solution Write the formulas for the following. A. calcium nitrateCa 2+, NO 3 − Ca(NO 3 ) 2 B. boron trifluoride 1 B, 3 F BF 3 C. aluminum carbonateAl 3+, CO 3 2− Al 2 (CO 3 ) 3 D. dinitrogen tetroxide 2 N, 4 ON 2 O 4 E. copper(I) phosphateCu +, PO 4 3− Cu 3 PO 4

24 Predicting Compounds using Lewis Dot Structures Going back to the idea of Lewis dot configuration as a good way to keep track of valence electrons for predicting structure of ionic/covalent compounds.

25 Ionic Compounds Magnesium Iodide using the crossover method to determine the molecular formula and draw the structure using Lewis dot valence electrons. Step 1: Forming the magnesium cation: Mg 2+ Mg + 2e - Step 2: Forming the iodide anion: I + 1e - I

26 Step 3: Putting the ions together We need 2 iodide anions to balance the +2 charge on the magnesium, as indicated by the formula MgI 2 I Mg 2+ I

27 Covalent Compounds Covalent compounds between oxygen and hydrogen Step 1: Determine how many bonds are formed by oxygen Step 2: Determine how many hydrogen atoms are in the chemical formula (hydrogen forms a single bond) Step 3: Draw the structure

28 Draw the structure for H 2 O O 6 valence e - 2 max bonds O H H O H 2 6 valence e - and 1 valence e - H2OH2O H 1 bond each

29 Covalent Compounds Covalent compounds between carbon and hydrogen Step 1: Determine how many bonds are formed by carbon Step 2: Determine how many hydrogen atoms are in the chemical formula (hydrogen forms a single bond) Step 3: Draw the structure

30 Draw the structure for CH 4 H1 valence e - 1 bond each 4 valence e - 4 max bonds C H 4 4 valence e - and 1 valence e - CH 4 C H H C H H