1. Chapter I Into to chem

2. What is Chemistry? Chemistry is defined as the study of matter and the changes that s undergoes. That being said chemistry is every part of your life From cooking your dinner To texting you friend Keeping your food cold and fresh To maintaining this room temperature so that we are not all sweating to death So lets take a look at two discovers that had an effect on each other Refrigeration and solar energy

3. The Ozone Layer As we know the earths atmosphere is made up of layers. The stratosphere is where the ozone layer resides The ozone layer protects the earths from UV rays UVB rays are more harmful then UVA rays Too much exposer to this radiation leads to things like Sunburn Skin cancer Poor crop YIELDS And is used to sterilize So what is Ozone Ozone is a substance that is made up of oxygen and absorbed the most harmful radiation before it reaches earth’s surface A substance, which is also known as a chemical, is matter that has a definite and uniform composition.

4. Ozone formation Oxygen gas (O 2 ) is exposed to ultraviolet radiation in the upper region of the stratosphere Oxygen particles are formed from the oxygen gas. These particles then react with oxygen gas to form ozone (O 3 ) The ozone can break apart to reform Oxygen gas (O 2 ) thus forming a balanced system. Ozone was identified in the late 1800’s In the 1920’s a British scientist G.M.B. Dobson began to measuring the amount of ozone in the atmosphere. Dobson figure out the a normal amount of ozone in the stratosphere is three hundred DU DU= Dobson Units In 1981-83 scientists in Antarctica found that the amount of ozone was surprisingly low. As low as 160 DU In 1985 they declared a thinning of the ozone in this part of the world later to become known as the Hole in the Ozone Now the question became, What caused the Hole?

5. CFC’s In the 1970’s scientists noticed that the amount of CFC’s in the atmosphere were rising. But since CFCs are so stable it was of no concern but they continued to monitor the levels By 1990 CFC’s levels were at an all time high. So science found this safe substance and all was great with the world again But we know the world doesn’t work this way. End 1-1

6. Chemistry and Matter Matter Makes up everything in the universe Mass This is the amount of matter that an object is made up of Weight Is a measure of both the matter in an object but also the effect of Earth’s gravitational pull on that matter This means that things on the moon have different weights but the same mass Weight actually changes on earth based on sea level You weigh less the higher above sea level you are

7. What can we learn by looking We as scientists call what you can see as observations When we look at something we know that more is going on then what we can see. Some times we need a microscope to observe more Sometimes it requires x-rays or means of detection In chemistry we try to explain things in terms of submicroscopic events Chemists use models to try to describe what is going on A model is a visual, verbal, or mathematical explanation of experimental data.

8. Chemistry: the Central Science All science needs chemistry So chemistry is broken into different branches that focus on different areas Organic chemistryMost carbon-containing chemicals Pharmaceuticals, plastics Inorganic chemistryMatter that does not contain carbon Minerals, martials and nonmetals, semiconductors Physical chemistryThe behavior and changes of matter and the related energy changes Reaction rates, reaction mechanisms Analytical chemistryComponents and composition of substances Food nutrients, quality control BiochemistryMatter and processes of living organisms Metabolism, fermentation

9. More branches end 1- 2 Environmental chemistryMatter and the environmentPollution, biochemical cycles Industrial chemistryChemical processes in industryPaints, coatings Polymer chemistryPolymers and plasticsTextiles, coatings, plastics Theoretical chemistryChemical interactionsMany areas of emphases ThermochemistryHeat involved in chemical processes Heat of reaction

10. The Scientific Method Scientists use a designed way to come up and test new ideas that involves several steps Observation Hypotheses Experiments Conclusion Revise hypothesize Re-experiment Revise conclusion

11. Observation Observations are things we all do everyday. We call this data The desk is hard, black. But what about how long? Tall? Two types of data Qualitative Color, odor, shape, or some other physical characteristic Using your senses Quantitative How much, how little, how big, how fast, how tall? These use numbers Or quantities

12. Chlorofluorocarbons In the 1920’s refrigerators used toxic gases sush as ammonia as coolants Problem with these is they would leak and harm members of the household so the chemists started a search for better coolants. Thomas Midgley, Jr. synthesized the first chlorofluorocarbons in 1928 Chlorofluorocarbon or CFC is made from chlorine, fluorine and carbon. Lots of different substances are classified as CFC’s They don’t occur naturally They are nontoxic and stable Don’t react with other substances So it seemed that they were safe the answer to all the cooling problems They were so safe the were also used in plastic foams and propellants in spray cans

13. Hypothesis A hypothesis is a tentative explanation for what has been observed Think about the ozone and CFC’s From what we know the hypothesis that CFC’s are destroying ozone can be made however unless there is good evidence this is only a guess. Ex. Claypool walks with a limp therefore he has a bad hip. Claypool’s classroom is full of penguins therefore he likes birds.

14. Experiments An experiment is a set of controlled observations that test the hypothesis When we want to test something the more things we can control the better. These are called variables Not controlling these leads to bad results In a well set up experiment there is only two changing variables The independent variable is the on the that we change Salt dissolves better in hot water, the independent variable is how hot the water is The dependent variable is the one that changes based on the changes to the independent variable How fast the salt dissolves? In order to tell the difference we need to know how fast salt will dissolve in room temperature water. This is called the control Without a control we have nothing to compare

15. Conclusion After the experiment and the results are known if these results support the hypothesis or not a conclusion can be made. If the results support the hypothesis this does not mean that its true. If the results disprove the hypothesis then the hypotheses is either discarded or modified. Time does not have a factor a hypothesis can be disproven an hour after it is purposed or 100 years after it was purposed There is a saying in science “Nothing can ever be proven only disproven.

16. Theory and Scientific law Once a hypothesis has been tested many times and there are experimental and natural phenomenon that supports it then it becomes a theory. Once a theory has been tested and scientists agree apon the validity of it, it becomes a scientific law Law of gravity Newtons laws of motion End 1-3

17. Scientific Research Pure research is done to gain knowledge for the sake of knowledge itself Done just to figure things out Applied research is done to solve a specific problem The amount of CFC’s in the atmosphere effect the amount of ozone Applied research was done to find a replacement for CFC’s This leads to chance discoveries Teflon Penicillin