Molecular Compounds

1. Molecular Compounds Writing Names and Formulas Section 9.3

2. Objectives Interpret the prefixes in the names of molecular compounds in terms of their chemical formulas Name and write formulas for binary molecular compounds

3. Review - Tell whether each compound is ionic or molecular • NaCl • H2O2 • CO2 • KBr • Ga2O3 • NO

4. Molecular compounds • Composed of molecules, not ions, so ionic charges cannot be used to write formulas or to name them. • When two nonmetallic elements combine, they often do so in more than one way. • For example: Carbon and oxygen can form CO and CO2 • Neither is called “carbon oxide”

5. Molecular Compounds • Because there are many sharing possibilities between two non-metals, the formula cannot be known unless the name reveals the number of atoms involved. • 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.

6. Prefixes – Learn these!! • 6 hexa- • 7 hepta- • 8 octa- • 9 nona- • 10 deca- 1 mono- 2 di- 3 tri- 4 tetra- 5 penta-

7. Naming Binary Molecular Compounds • To write the name, write two words: • Exception- we don’t write mono- if there is only one of the first element. • No aooo double vowels when writing name. • io, oi, ii, and ai are okay. • All names of binary molecular compounds end in – ide. Prefix name Prefix name -ide

8. Name These • N2O • NO2 • Cl2O7 • MgBr2 • CBr4 • CO2 • BaCl2

9. Write formulas for these • diphosphoruspentoxide • tetraiodinenonoxide • sulfur hexafluoride • nitrogen trioxide • carbon tetrahydride • phosphorus trifluoride • aluminum chloride