1. © Copyright Pearson Prentice Hall Slide 1 of 15 Naming and Writing Formulas for Molecular Compounds One milligram of gold is worth only about one cent, but one kilogram of gold is worth approximately $12,500. The correct prefix ( milli- or kilo-) makes quite a difference! Prefixes are important in chemistry, too. The prefixes in the name of a binary molecular compound tell you its composition. 9.3

2. © Copyright Pearson Prentice Hall Naming and Writing Formulas for Molecular Compounds > Slide 2 of 15 Naming Binary Molecular Compounds What does a prefix in the name of a binary molecular compound tell you about the compound’s composition? 9.3

3. Slide 3 of 15 © Copyright Pearson Prentice Hall Naming and Writing Formulas for Molecular Compounds > Carbon and oxygen combine to form carbon monoxide (CO) and carbon dioxide (CO 2 ), but these two invisible gases are very different. 9.3 Naming Binary Molecular Compounds

4. Slide 4 of 15 © Copyright Pearson Prentice Hall Naming and Writing Formulas for Molecular Compounds > Sitting in a room with small amounts of CO 2 in the air would not present any problems. If the same amount of CO were in the room, you could die of asphyxiation. A naming system that distinguishes between these two compounds is needed. 9.3 Naming Binary Molecular Compounds

5. Slide 5 of 15 © Copyright Pearson Prentice Hall Naming and Writing Formulas for Molecular Compounds > A prefix in the name of a binary molecular compound tells how many atoms of an element are present in each molecule of the compound. 9.3 Naming Binary Molecular Compounds

6. Slide 6 of 15 © Copyright Pearson Prentice Hall Naming and Writing Formulas for Molecular Compounds > Some guidelines for naming binary molecular compounds: Name the elements in the order listed in the formula. Use prefixes to indicate the number of each kind of atom. 9.3 Naming Binary Molecular Compounds

7. Slide 7 of 15 © Copyright Pearson Prentice Hall Naming and Writing Formulas for Molecular Compounds > Omit the prefix mono- when the formula contains only one atom of the first element in the name. The suffix of the name of the second element is -ide. 9.3 Naming Binary Molecular Compounds

8. Slide 8 of 15 © Copyright Pearson Prentice Hall Naming and Writing Formulas for Molecular Compounds > Writing Formulas for Binary Molecular Compounds How do you write the formula for a binary molecular compound? 9.3

9. Slide 9 of 15 © Copyright Pearson Prentice Hall Naming and Writing Formulas for Molecular Compounds > 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. 9.3 Writing Formulas for Binary Molecular Compounds

10. Slide 10 of 15 © Copyright Pearson Prentice Hall Naming and Writing Formulas for Molecular Compounds > Silicon carbide is a hard material like diamond. The name silicon carbide has no prefixes, so the subscripts of silicon and carbon must be one. Thus, the formula for silicon carbide is SiC. 9.3 Writing Formulas for Binary Molecular Compounds

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