1. Introduction to Chemistry Chapter 1

2. 1.1: A Story of Two Substances  Chemistry is the study of matter and the changes it undergoes How is chemistry important in our lives?

3. 1 st Substance - The Ozone Layer  The substance that absorbs most harmful radiation before it reaches Earth’s surface is a substance called ozone. A substance is matter with definite and uniform composition.  When oxygen gas is exposed to ultraviolet radiation in the upper stratosphere, the oxygen atoms split apart and react with other molecules of oxygen gas to form ozone.

4. The Ozone Layer  Ozone can also break apart to reform oxygen gas.  In the early to mid-1980s scientist confirmed that the ozone layer above Antarctica was thinning.  What could be causing this “hole”?

5. 2 nd Substance - Chlorofluorocarbons  Coolants such as ammonia were originally used in refrigerators  toxic!  Chlorofluorocarbons (CFCs) were developed to solve this problem and were used in AC units, refrigerators, plastic foams, solvents, and propellants.  Between 1970-1990 scientists confirmed an increase in CFCs in the atmosphere.  Why weren’t they concerned?

6. 1.2 – Chemistry and Matter  Matter and it’s Characteristics Matter is everything that has mass and takes up space.  Mass versus Weight Why is it important to think of matter in terms of mass instead of weight? Macroscopic versus Submicroscopic  Models

7. Chemistry – The Central Science  A basic understanding of chemistry is central to all sciences – biology, physics, Earth science, ecology, and others. Organic chemistry Inorganic chemistry Physical chemistry Analytical chemistry Biochemistry Environmental chemistry Industrial chemistry Polymer chemistry Theoretical chemistry Thermochemistry

8. 1.3 – Scientific Methods  Observation Qualitative and Quantitative Data  Hypothesis  Experiments Independent and Dependent Variables Control  Conclusion  Theory and Scientific Law

9. Hypothesis, Theory, and Law  A hypothesis can never be proven. It can be supported by data in an experiment or it can be discarded or modified if data does not support it.  A theory is an explanation of a natural phenomenon based on many observations and investigations over time.  A scientific law summarizes a relationship in nature supported by many experiments.

10. 1.4 Scientific Research  Pure research  Applied research  Chance Discoveries

11. The 2 Substances – CFCs and Ozone  Mario Molina and F. Sherwood Rowlands were curious about how long CFCs could exist in the atmosphere.  They hypothesized that CFCs break down in the atmosphere due to interactions with UV light and that chlorine products from this reaction would break down ozone. What part(s) of the scientific method is/are described? What type of scientific research is this?

12. The 2 substances – CFCs and Ozone  Molina and Rowland gathered data that supported their hypothesis.  They developed a model in which chlorine products would react repeatedly with ozone. Another research group confirmed this data but did not know the source of the chlorine. Molina and Rowland’s model predicted a source of the chlorine. What part of the scientific method is described above?

13. The 2 substances – CFCs and Ozone  Molina and Rowland determined that ozone in the stratosphere could be destroyed by CFCs. They published their discovery and won the Nobel Prize in 1995.  Scientists continue to monitor the amount of CFCs and annual ozone changes in the atmosphere. Researchers are working to find replacement chemicals for CFCs. What part of the scientific method is described above? What type of scientific research is described above?