1. compare the information provided by a molecule’s chemical formula to the information provided by its structural formula.

2. what is the major difference between the two-dimensional and three- dimensional models of propane and ethene? when might you choose to use a two-dimensional model rather than a three-dimensional model when representing one of the molecules?

3. use the internet to research how chemists know that an oxygen molecule has unpaired electrons. summarize the reason in at least 2-3 sentences.