1. Naming and Writing Formulas for Molecular Compounds Names and Formulas Chapter 9 Section 3

2. Key Questions What guidelines are used to write the name and formula of a binary molecular compound? 2

3. Naming Binary Molecular Compounds To name a binary molecular compound, use the following guidelines. 1.Write the name of the elements in the order listed in the formula. 2.Use prefixes appropriately to indicate the number of each kind of atom. 3.End the name of the second element with the suffix –ide. 3

4. Naming Binary Molecular Compounds 4

5. 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. 5

6. Ionic or Molecular Compounds PBr 3 and CrBr 3 – CrBr 3 is ionic – CrBr 3 chromium bromide – PBr 3 is molecular – Phosphorous tribromide 6

7. Ionic or Molecular Compounds N 2 O and Na 2 O – Na 2 O is ionic – Sodium oxide – N 2 O is molecular – Dinitrogen oxide 7

8. Ionic or Molecular Compounds Cl 4 and PbI 4 – PbI 4 is ionic – Lead (IV) iodide – CI 4 is molecular – Carbon tetraiodide 8

9. Ionic or Molecular Compounds P 2 O 3 and Fe 2 O 3 – Fe 2 O 3 is ionic – Iron (III) oxide – P 2 O 3 is molecular – Diphoshorous trioxide 9

10. Summary 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 subscripts of each element. Write the symbols for the elements with the subscripts. 10