1. Chapter 1 Introduction to Chemistry

2. Chemistry is all around you!  Chemistry at home:  Chemistry in the classroom:

3. 1.1 A Story of 2 Substances  Chemistry – the study of matter and the changes it undergoes. Matter:

4. The Ozone Layer  Ozone chemical formula:  Substance in the atmosphere that absorbs harmful UV radiation before it reaches the Earth’s surface Substance  Aka –  Matter that has a definite and uniform composition

5.  Ozone formation:  UV radiation breaks oxygen molecules apart  Individual oxygens react with oxygen molecules to form ozone

6.  Levels of ozone can be measured by balloons, satellites, and rockets.  1980s – scientists realized ozone layer getting thinner

7. Chlorofluorocarbons  Made of chlorine, fluorine, and carbon  Developed in 1928 as refrigerator coolant  Also used in air-conditioners, plastic foams, and as propellants in spray cans

8.  Scientists began to measure CFC levels in 1970s  By 1990 concentrations had reached all time high

9.  Is there a connection between depleting ozone layer and the increase in CFCs?

10. 1.2 Chemistry and Matter  Everything around you is matter  Chemists study matter  Conclusion:

12. Matter and its Characteristics  Matter =  Mass – amount of matter in an object

13.  Weight – the amount of matter in an object and the effect of gravity on that matter  What is the difference between mass and weight?

14.  What happens to your weight if you go to the moon?  What happens to your mass if you go to the moon?

15.  Much of matter and its behavior is macroscopic Macroscopic -

16.  The structure, composition, and behavior of all matter can be described on a submicroscopic (atomic) level  Models are used to observe data that is submicroscopic Model – visual, verbal, or mathematical explanation of experimental data

17. 1.3 Scientific Methods  Scientists use scientific methods to systematically pose and test solutions to questions and assess the results of the tests

18. A Systematic Approach  Scientific method – a systematic approach used in scientific study. Organized process used by scientists to do research Provides method for scientists to verify work of others Steps repeated until hypothesis is supported or discarded

20. Observation  Scientific study usually begins with simple observations  Types of observation: Qualitative – how something looks, feels, sounds, tastes, smells  Ex: Quantitative – uses numbers  Ex:

22. Hypothesis  Tentative explanation for what has been observed  Ex: CFCs break down due to interactions with UV light from the sun & Cl released breaks down ozone

23. Experiments  Set of controlled observations that test the hypothesis  Must be set up carefully in order to change and test only one variable at a time

24. Parts of an experiment  You want to test the hypothesis that a beaker of water under a lamp will evaporate faster than a beaker of water on the counter. You add 50 mL of water to 2 beakers and place one on the counter and one under a lamp. You measure the amount of water in each beaker every 30 minutes.

25.  Independent variable – the thing the scientist is testing the effect of (changes)

26.  Dependent variable – the thing the scientist measures Dependent on the independent variable

27.  Constant – factor that is not allowed to change during the experiment

28.  Control – standard for comparison, does not receive the independent variable

29. Conclusion  Judgment based on the information obtained  Hypothesis can never be proven or disproved, only supported or not supported

30.  Scientists gathered data and developed models that supported the hypothesis that Cl released by CFCs reacts with ozone and depletes it.

31. Theory and Scientific Law  Theory – explanation of a natural phenomenon based on many observations and investigations over time Broad principle of nature that has been supported over time Can be modified Atomic theory

32.  Scientific Law – relationship in nature that is supported by many experiments Gravity

33. 1.4 Scientific Research  Scientific investigations result in the development of technology that can improve our lives and the world around us.

34. Types of Scientific Investigations  Pure research – conducted to gain knowledge for the sake of knowledge itself  Applied research – research done to solve specific problems

35.  Chance discoveries – occur when scientists obtain results that are far different from what they expected  Penicillin – accidentally discovered when a bacterial sample being studied became contaminated with it

36. What ever happened to that ozone?  CFCs and ozone concentrations are continuously monitored  Montreal Protocol – 1987, nations agreed to phase out use of CFCs

37. Ozone hole today  Forms each year over Antarctica during the spring  Scientists use models to predict the ozone will not begin to recover until 2068