Chapter 2 Chemistry

1. Chapter 2 Chemistry

2. It is important to know the chemistry that is involved in the cycling of nutrients, resource use, and pollution. • Some of our chemicals are naturally occurring and some anthropogenic (manmade)

3. The Chemistry of Carbon, Nitrogen, Oxygen, Phosphorus, & Sulfur • Carbon= Backbone of all organic compounds including all of the important molecules found in living organisms Fossil Fuels and Carbon dioxide (important green house gas)

4. Nitrogen= Most abundant element in the earth’s atmosphere at 78 %. Found in the amino group of every amino acid, the building block of protein Nitrogen runoff from agricultural land is an important contributor to nutrient pollution in waterways. Nitrous oxide is an important greenhouse gas

5. Oxygen= The second most abundant element in the atmosphere at 21 % • Most abundant element in the earth’s crust • Oxygen was added later into the atmosphere through photosynthesis of green plants • Necessary for cellular respiration

6. Phosphorus= Component of nucleic acids and phospholipids • Sulfur is a major constituent of volcanic eruptions and a contaminant of coal that contributes to acid rain

7. Defining Matter • Matter is anything that has mass • Found in 2 chemical forms elements & compounds • Matter Quality= is a measure of how useful a form of matter is to humans as a resource based on its availability.

8. High Quality Matter= easier to extract and is concentrated. Found near earth’s surface & has greater potential for use • Low Quality matter=located deep underground or dispersed in ocean or atmosphere. Has little potential for use.

9. Physical & Chemical Changes • Physical change is when the chemical composition does not change. (Solid ice melting into liquid) • Chemical change is when rearrangement of atoms occurs and get a different product (Chemical reaction) Coal + Oxygen = Carbon dioxide + energy With chemical reactions energy is released

10. Law of Conservation of Matter • When a physical or chemical change occurs, no atoms are created or destroyed • There is no “away” in to throw “away” • Everything remains with us in some form • We can remove harmful substances but cannot get rid of it

11. Types of Pollutants • We can always produce some pollutants but we can always produce much less and clean up. • Persistence is the measure of how long the pollutant stays in the air, water, soil, or body • 4 Categories

12. Degradable= broken down completely • Biodegradable= Living organisms break down • Slowly Degradable= takes decades to degrade Example includes insecticide DDT and most plastics • Nondegradable= Cannot be broken down Examples include mercury, lead, arsenic Law of Conservation of Matter means we will always face the problem of what to do with some quantity of wastes and pollutants

13. Nuclear Changes: Radioactive Decay, Fission & Fusion • Natural Radioactive Decay: Unstable isotopes release chunks of matter (particles) • Decay continues until it produces a stable isotope that is not radioactive • Each isotope decays at a specific rate (This rate is called half life) • It can be used to estimate how long a sample must be stored before it decays to a safe level.

14. Experimental Design • Most common type of experiment= controlled experiment • Don’t forget the control! • Write a testable hypothesis (If… then…..because) • Isolate one variable to measure and one variable to manipulate

15. Experimental Design • Independent Variable is manipulated during the experiment • Dependent Variable is measured during the experiment Example: Design an experiment to determine how soil pollution affects elderberry bushes. 1. Select two variables, one you can manipulate and one you can measure

16. Experimental Design • Manipulate the concentration of a pollutant (salt) • Pick something you measure (the number of elderberries produced by each bush) • Hypothesis: Increased salt concentration in soil result in a decrease in the number of berries

17. Experimental Design • Don’t forget the control! • Collect and analyze data • Draw Conclusions

18. FRQ Practice • Unit #1- APES- FRQ • For thousands of years, clams have been dug up along the beaches of California for food, first by Native Americans, and these days often by tourists. Today, the clam population is at an all-time low, and many scientists agree that several species of clams will inevitably become extinct in California. Dr. Kim, a marine biologist, believes that DDT dumped into the ocean during the 1950’s and 60’s could be another factor in the dramatic decrease in the clam population.

19. Write an argument to explain why the decline in the clam population could be considered an example of a tragedy of the commons. • Identify and describe two strategies that could be employed to prevent any decline in the clam population due to a tragedy of the commons. • Design a controlled experiment to support or refute the claim by Dr. Kim that DDT is playing a role in the clam’s demise. Include a detailed description of the experiment that includes the hypothesis being tested, a description of the data being collected, and identification of the dependent and independent variables in the experiment.