1. Chapter 4 Compounds and Their Bonds 4.5 Covalent Compounds and Their Names 1 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

2. Covalent Bonds Covalent compounds form when atoms share electrons to complete octets between nonmetal atoms from Groups 4A, 5A, 6A, and 7A 2 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

3. Formation of a Hydrogen Molecule A hydrogen molecule, H 2, forms as the atoms move closer and the nucleus of one atom attracts the electron of the other is stable with 2 electrons (helium) has a shared pair of electrons 3 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

4. Formation of a Hydrogen Molecule – H 2 A covalent bond forms as H atoms move close together to share electrons. 4 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

5. Formation of Octets in Molecules – F 2 In a fluorine, F 2,, molecule, each F atom shares one electron to attain an octet. 5 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

6. Writing Electron-Dot Formulas To draw the electron-dot formula for methane, CH 4, we start with the electron-dot symbols for carbon and hydrogen we need four hydrogen atoms to complete carbon’s octet 6 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

7. Double and Triple Covalent Bonds A double bond: occurs when atoms share two pairs of electrons forms when there are not enough electrons to complete octets A triple bond: occurs when atoms share three pairs of electrons forms when there are not enough electrons to complete octets 7 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

8. Guide to Drawing Electron-Dot Formulas 8 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

9. Electron-Dot Formulas for Some Covalent Compounds – CO 2 Step 1Determine the arrangement of atoms. O C O Step 2Determine the total number of valence electrons. C 2(O)= CO 2 4e− + 2(6−) = 16e− 9 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

10. Electron-Dot Formulas for Some Covalent Compounds – CO 2 Step 3 Attach each bonded atom to the central atom with a pair of electrons. Step 4 Place the remaining electrons using single or multiple bonds to complete octets. 10 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

11. Triple Bond – N 2 In a nitrogen molecule, N 2, each N atom shares three electrons to gain an octet the multiple bond formed is called a triple bond the name is the same as the element 11 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

12. Names and Formulas of Covalent Compounds When naming covalent compounds: the first nonmetal in the formula is named by its element name the second nonmetal is named by using the first syllable of its name followed by ide if a subscript is used in the formula a prefix is used in front of its name when vowels o and o or a and o appear together, the first vowel is omitted 12 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

13. Guide to Naming Covalent Compounds 13 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

14. Prefixes Used in Naming Covalent Compounds 14 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

15. Naming Covalent Compounds – NCl 3 Name the covalent compound NCl 3. Step 1 Name the first nonmetal by its element name. The first nonmetal (N) is nitrogen. Step 2 Name the second element by using the first syllable of its name followed by ide. The second nonmetal (Cl) is chloride. 15 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

16. Naming Covalent Compounds – NCl 3 Step 3Add prefixes to indicate number of atoms. Because there is one nitrogen atom, no prefix is needed. The subscript three for the Cl atoms is shown as the prefix tri. NCl 3, nitrogen trichloride 16 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

17. Some Common Covalent Compounds 17 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

18. Learning Check 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 18 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

19. Solution 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 19 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

20. Learning Check Write the name of each covalent compound. A. CO B. NO 2 C. PF 3 D. CCl 4 20 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

21. Solution Write the name of each covalent compound. Step 1 Name the first nonmetal by its element name. A. CO The first nonmetal (C) is carbon. B. NO 2 The first nonmetal (N) is nitrogen. C. PF 3 The first nonmetal (P) is phosphorus. D. CCl 4 The first nonmetal (C) is carbon. 21 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

22. Solution Write the name of each covalent compound. Step 2 Name the second element by using the first syllable of its name followed by ide. A. CO The second nonmetal (O) is oxide. B. NO 2 The second nonmetal (O) is oxide. C. PF 3 The second nonmetal (F) is fluoride. D. CCl 4 The second nonmetal (Cl) is chloride. 22 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

23. Solution Write the name of each covalent compound. Step 3Add prefixes to indicate number of atoms. A.COBecause there is one carbon atom, no prefix is needed. The subscript 1 for the O atom is shown using the prefix mono. CO is carbon monoxide. B.NO 2 Because there is one nitrogen atom, no prefix is needed. The subscript 2 for the O atoms is shown using the prefix di. NO 2 is nitrogen dioxide. 23 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

24. Solution Write the name of each covalent compound. Step 3 Add prefixes to indicate number of atoms. C.PF 3 Because there is one phosphorus atom, no prefix is needed. The subscript 3 for F atoms is shown using the prefix tri. PF 3 is phosphorus trifluoride. D.CCl 4 Because there is one carbon atom, no prefix is needed. The subscript 4 for the Cl atoms is shown using the prefix tetra. CCl 4 is carbon tetrachloride. 24 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

25. Writing Formulas for Covalent Compounds 25 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

26. Writing Formulas for Covalent Compounds – Diboron Trioxide Write the formula for the covalent compound diboron trioxide. Step 1Write the symbols in order of the elements in the name. The first nonmetal is boron (B) and the second nonmetal is oxygen (O). B O Step 2Write any prefixes as subscripts. The prefix di in diboron indicates there are two boron atoms and is shown as a subscript after B. The prefix tri in trioxide indicates there are three oxygen atoms and is shown as a subscript after O. B 2 O 3 26 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

27. Learning Check Write the correct formula for each of the following: A. phosphorus pentachloride B. dinitrogen trioxide C. sulfur hexafluoride 27 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

28. Solution Write the correct formula for each of the following: Step 1Write the symbols in order of the elements in the name. A.phosphorus pentachloride The first nonmetal is phosphorus, (P) and the second nonmetal is chlorine, (Cl). P Cl B.dinitrogen trioxide The first nonmetal is nitrogen, (N) and the second nonmetal is oxygen, (O). N O C.sulfur hexafluoride The first nonmetal is sulfur, (S) and the second nonmetal is fluorine, (F). S F 28 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

29. Solution Write the correct formula for each of the following: Step 2 Write any prefixes as subscripts. A. phosphorus pentachloride: No prefix for phosphorus indicates there is 1 phosphorus atom. The prefix penta in pentachloride indicates there are 5 chlorine atoms, and is shown as a subscript after Cl. PCl 5 B.dinitrogen trioxide: The prefix di in dinitrogen indicates there are 2 nitrogen atoms and is shown as a subscript after N. The prefix tri in trioxide indicates there are 3 oxygen atoms and is shown as a subscript after O. N 2 O 3 29 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

30. Solution Write the correct formula for each of the following: Step 2Write any prefixes as subscripts. C.sulfur hexafluoride: No prefix for sulfur indicates there is 1 sulfur atom. The prefix hexa in hexafluoride indicates there are 6 fluorine atoms and is shown as a subscript after F. SF 6 30 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

31. Summary to Naming Simple Compounds 31 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

32. 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 3 D. Cu 2 CO 3 E. N 2 O 4 32 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

33. Study Tip: Ionic or Covalent A compound is ionic if the first element in the formula or the name is a metal or the polyatomic ion NH 4 + K 2 O K is a metal; compound is ionic; potassium oxide covalent if the first element in the formula or the name is a nonmetal N 2 O N is a nonmetal; compound is covalent; dinitrogen oxide 33 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

34. 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 34 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.