1. 9.3 Naming and Writing Formulas for Molecular Compounds 1 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Chapter 9 Chemical Names and Formulas 9.1 Naming Ions 9.2 Naming and Writing Formulas for Ionic Compounds 9.3 Naming and Writing Formulas for Molecular Compounds 9.4 Naming and Writing Formulas for Acids and Bases 9.5 The Laws Governing How Compounds Form

2. 9.3 Naming and Writing Formulas for Molecular Compounds 2 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. What numerical prefixes are used in chemistry? The word triathlon contains the prefix tri-, indicating the number 3. Prefixes are used in chemistry, too. CHEMISTRY & YOU

3. 9.3 Naming and Writing Formulas for Molecular Compounds 3 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Prefixes used in molecular compounds names. Binary Molecular Compounds Naming Binary Molecular Compounds Prefixes Used in Naming Binary Molecular Compounds PrefixNumber mono-1 di-2 tri-3 tetra-4 penta-5 hexa-6 hepta-7 octa-8 nona-9 deca-10

4. 9.3 Naming and Writing Formulas for Molecular Compounds 4 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Recall that binary ionic compounds are composed of the ions of two elements, a metal and a nonmetal. Binary molecular compounds are also composed of two elements, but both elements are nonmetals and are not ions. Binary molecular compounds are composed of molecules, so ionic charges cannot be used to write formulas or to name them. Binary Molecular Compounds

5. 9.3 Naming and Writing Formulas for Molecular Compounds 5 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Before you apply the steps for naming molecular compounds from their formulas, you must confirm that the compound is a binary molecular (contains only non-metals) compound. That is done by counting CAPITAL LETTERS and MATCHING up symbols. Binary Molecular Compounds Naming Binary Molecular Compounds

6. 9.3 Naming and Writing Formulas for Molecular Compounds 6 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Binary Molecular Compounds What guidelines are used to write the name and formula of a binary molecular compound? Binary Molecular Compounds

7. 9.3 Naming and Writing Formulas for Molecular Compounds 7 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. To name a binary molecular compound, use the following guidelines. 1.Write the names of the elements in the order listed in the formula. Binary Molecular Compounds

8. 9.3 Naming and Writing Formulas for Molecular Compounds 8 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. To name a binary molecular compound, use the following guidelines. 1.Write the names of the elements in the order listed in the formula. 2.Use prefixes appropriately to indicate the number of each kind of atom. Binary Molecular Compounds

9. 9.3 Naming and Writing Formulas for Molecular Compounds 9 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. To name a binary molecular compound, use the following guidelines. 1.Write the names of the elements in the order listed in the formula. 2.Use prefixes appropriately to indicate the number of each kind of atom. If just one atom of the first element is in the formula, omit the prefix mono- for that element. Binary Molecular Compounds

10. 9.3 Naming and Writing Formulas for Molecular Compounds 10 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. To name a binary molecular compound, use the following guidelines. 1.Write the names of the elements in the order listed in the formula. 2.Use prefixes appropriately to indicate the number of each kind of atom. If just one atom of the first element is in the formula, omit the prefix mono- for that element. 3.End the name of the second element with the suffix -ide. Binary Molecular Compounds

11. 9.3 Naming and Writing Formulas for Molecular Compounds 11 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. When two nonmetallic elements combine, they often do so in more than one way. The elements carbon and oxygen combine to form two gaseous compounds, CO and CO 2. It might seem satisfactory to call both of these compounds carbon oxide but they are VERY different. Binary Molecular Compounds

12. 9.3 Naming and Writing Formulas for Molecular Compounds 12 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. CO is a poisonous gas that interferes with your blood’s ability to carry oxygen to body cells. You exhale CO 2 as a product of your body chemistry, and is vital for the production of oxygen gas in green plants. Binary Molecular Compounds

13. 9.3 Naming and Writing Formulas for Molecular Compounds 13 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Prefixes in the names of binary molecular compounds tell how many atoms of an element are present in each molecule of the compound. The prefix mono- would be used for the single oxygen atom in CO. The prefix di- would be used for the two oxygen atoms in CO 2. Binary Molecular Compounds Naming Binary Molecular Compounds

14. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. How does phosphorus trifluoride differ from phosphorus pentafluoride?

15. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. How does phosphorus trifluoride differ from phosphorus pentafluoride? Phosphorus trifluoride is a binary molecular compound that has 1 phosphorus and 3 fluoride atoms, while phosphorus pentafluoride contains 1 phosphorus and 5 fluoride atoms.

16. 9.3 Naming and Writing Formulas for Molecular Compounds 16 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Following the guidelines, CO is named carbon monoxide and CO 2 is named carbon dioxide. Cℓ 2 O 8 consists of two chlorine atoms and eight oxygen atoms. The name is therefore dichlorine octoxide. Binary Molecular Compounds Naming Binary Molecular Compounds

17. 9.3 Naming and Writing Formulas for Molecular Compounds 17 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Sample Problem Naming Binary Molecular Compounds Name the following binary molecular compounds. a. N 2 Br b. HCℓ 3 c. C 4 O 4

18. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Sample Problem Analyze Identify the relevant concepts. Confirm that the compound is a binary molecular compound—a compound composed of two nonmetals. To name the compound, name the elements in the order written in the formula. Use prefixes as necessary to indicate the number of each kind of atom. Use the suffix -ide on the name of the second element. 1

19. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Solve Apply the concepts to this problem. Identify the elements in the compound and the number of atoms of each element in a molecule of the compound. a. N 2 Br is composed of two nonmetals, nitrogen and bromine. b. HCℓ 3 is composed of two nonmetals, hydrogen and chlorine. c. C 4 O 4 is composed of two nonmetals, carbon and oxygen. Sample Problem 2

20. 9.3 Naming and Writing Formulas for Molecular Compounds 20 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Sample Problem Solve Apply the concepts to this problem. Write the names of the elements in the order they are written in the formula. Include prefixes to show how many atoms of each element. Use the suffix -ide with the name of the second element. a.Each molecule of N 2 Br has: 2 nitrogen atoms; 1 bromine atom. N 2 Br is dinitrogen monobromide. 2

21. 9.3 Naming and Writing Formulas for Molecular Compounds 21 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Sample Problem Solve Apply the concepts to this problem. Write the names of the elements in the order they are written in the formula. Include prefixes to show how many atoms of each element. Use the suffix -ide with the name of the second element. b. Each molecule of HCℓ 3 has: 1 hydrogen atom; 3 chlorine atoms. HCℓ 3 is hydrogen trichloride. 2 The prefix mono- is not used with the first element.

22. 9.3 Naming and Writing Formulas for Molecular Compounds 22 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Sample Problem Solve Apply the concepts to this problem. Write the names of the elements in the order they are written in the formula. Include prefixes to show how many atoms of each element. Use the suffix -ide with the name of the second element. a.Each molecule of C 4 O 4 has: 4 carbon atoms; 4 oxygen atom. C 4 O 4 is tetracarbon tetraoxide. 2

23. 9.3 Naming and Writing Formulas for Molecular Compounds 23 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Writing Formulas for Binary Molecular Compounds To write the formula of a binary molecular compound, first use the prefixes in the name to tell you the subscript of each element in the formula. Then, write the correct symbols for the two elements with the appropriate subscripts. Binary Molecular Compounds

24. 9.3 Naming and Writing Formulas for Molecular Compounds 24 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Tetraphosphorus trisulfide, which is used in some matches, has the prefixes tetra- and tri-, so the subscripts of phosphorus and sulfur must be 4 and 3, respectively. Thus, the formula for tetraphosphorus trisulfide is P 4 S 3. Binary Molecular Compounds Writing Formulas for Binary Molecular Compounds

25. 9.3 Naming and Writing Formulas for Molecular Compounds 25 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Sample Problem Writing Formulas for Binary Molecular Compounds Write formulas for the following binary molecular compounds. a. nitrogen octafluoride b. disulfur dichloride c. decaboron nonaiodide Note: The number 1 is never used as a subscript in a formula.

26. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Sample Problem Analyze Identify the relevant concepts. The prefixes in the name indicate the subscript of each element in the formula. Write the symbols for the two elements with the appropriate subscripts. 1

27. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Solve Apply the concepts to this problem. Use the prefixes to determine how many atoms of each element are in the compound. Sample Problem 2 a. Each molecule of nitrogen octafluoride has: 1 nitrogen atom; 8 fluorine atoms. b. Each molecule of disulfur dichloride has: 2 sulfur atoms; 2 chlorine atoms. c. Each molecule of decaboron nonaiodide has: 10 boron atoms; 9 iodine atoms.

28. 9.3 Naming and Writing Formulas for Molecular Compounds 28 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Solve Apply the concepts to this problem. Construct the formula using the correct symbols and subscripts. Sample Problem 2 a. 1 nitrogen atom; 8 fluorine atoms NF 8

29. 9.3 Naming and Writing Formulas for Molecular Compounds 29 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Solve Apply the concepts to this problem. Construct the formula using the correct symbols and subscripts. Sample Problem 2 b. 2 sulfur atoms; 2 chlorine atoms S 2 Cℓ 2

30. 9.3 Naming and Writing Formulas for Molecular Compounds 30 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Solve Apply the concepts to this problem. Construct the formula using the correct symbols and subscripts. Sample Problem 2 c. 10 boron atom; 9 iodine atoms B 10 I 9

31. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Compare and Contrast binary molecular compounds from binary ionic compounds?

32. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Compare and Contrast binary molecular compounds from binary ionic compounds? Binary molecular compounds are composed of two elements, which are nonmetals and are not ions. Binary ionic compounds are composed of the ions of two elements, a metal and a nonmetal.

33. 9.3 Naming and Writing Formulas for Molecular Compounds 33 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. To name a binary molecular compound, write the names of the elements in the order listed in the formula. Use prefixes to indicate the number of each atom. End the name of the second element with -ide. To write the formula of a binary molecular compound, use the prefixes to determine the subscript of each element. Write the symbols for the elements with the subscripts. Key Concepts

34. 9.3 Naming and Writing Formulas for Molecular Compounds 34 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. END OF 9.3