Science. Models, systems “Scientific knowledge is a body of statements of varying degrees of certainty – some most unsure, some nearly sure, and none absolutely certain” – Richard Feynman

Science and Technology Science – knowledge of how the world works Technology – creation of new processes intended to improve the quality of life

Scientific method HYPOTHESIS – proposed to explain observed patterns Critical experiments Analysis and conclusions

Scientific law and Theory Law – certain phenomena always act in a predictable manner Theory – rational explanation for numerous observations of a certain phenomena – global warming due to greenhouse effect

Accuracy Vs Precision Accuracy – measurement agrees with the accepted correct value Precision – measure of reproducibility

Types of reasoning Inductive - using observations and facts to arrive at generalizations Deductive - using logic to arrive at a specific conclusion

Models Mental models –perception, unreliable Conceptual – general relationships among components of a system Graphic – display data Physical – miniatures Mathematical – use of equations

Feedback loop Change in one part of a system influences another part of the system

Positive feedback loop Exponential growth of population – more individuals lead to increased number of births

Negative feedback loop Temperature regulation in humans – increased temperature leads to decrease in temperature by sweating

Complex systems Time lags – change in a system leads to other changes after a delay – lung cancer Resistance to change – built in resistance – political, economic Synergy-when two or more processes interact so that the combined effect is greater Chaos – unpredictable behavior in a system

Gaia Hypothesis (1970) James Lovelock and Lynn Marguilis proposes that organisms interact with their inorganic surroundings on Earth to form a self-regulating, complex system that contributes to maintaining the conditions for life on the planet

Important Terms Inputs - matter, energy, information Throughput - flow of input Output - matter, energy, information flowing out

Matter and Energy Resources Nature’s Building Blocks anything that has mass and takes up space

Forms of matter elements – single type of atoms 110 elements – 92 natural +18 synthesized compounds - 2 or more elements, held together by chemical bonds

Building Blocks atoms - smallest units of matter- protons,neutrons,electrons ion - electrically charged atoms molecules - combinations of atoms of the same or different elements

Definitions Atomic Number - number of protons Isotopes - same atomic number, different mass number Ions - atoms can gain or lose one or more electrons Mass Number - protons + neutrons

Isotope Elements with same atomic number but a different mass number

Some Important elements- composition by weight – only 8 elements make up 98.5% of the Earth’s crust

Organic Compounds with carbon sugar, vitamins, plastics, aspirin

Environmental Organic Compounds Hydrocarbons = methane gas Chlorinated hydrocarbons =. DDT, PCB Chlorofluorocarbons (CFC)- Freon 12

Polymers larger and more complex organic compounds made up of monomers complex carbohydrates proteins - 20 amino acids nucleic acids - nucleotides

Inorganic compounds no carbon,not originating from a living source Earth’s crust – minerals,water water, nitrous oxide, nitric oxide, carbon monoxide, carbon dioxide, sodium chloride, ammonia

Matter quality Measure of how useful a matter is for humans based on availability and concentration

Energy capacity to do work and transfer heat Kinetic Energy -energy in action electromagnetic radiation, heat, temperature Potential energy - stored energy that is potentially available

Electromagnetic radiation different wave lengths shorter – high energy, disrupts cells with long term exposure

Energy sources 97% solar without it earth’s temperature C 1% - non commercial(wood, dung, crops) + commercial ( burning mineral resources)

Energy quality Measure of how useful an energy source is in terms of concentration and ability to perform useful work

Law of Conservation of Matter elements and compounds changed from one form to another, can never be destroyed no “away” in “throw away”

Nuclear Changes nuclei of certain isotopes spontaneously change (radioisotopes) or made to change into one or more different isotopes Alpha particles – fast moving (2 protons+2neutrons); Beta particles – high speed electrons ; Gamma particles - high energy electromagnetic radiation radioactive decay, nuclear fission, nuclear fusion

Use….radioisotopes Estimate age of rocks and fossils Tracers in pollution detection and medicine Genetic control of insects

Half - Life time needed for one-half of the nuclei in a radioisotope to decay and emit their radiation. Goes through 10 half –lives before it becomes a non-radioactive form

Nuclear Fission certain isotopes (uranium 235) split apart into lighter nuclei when struck by neutrons chain reaction releases energy needs critical mass of fissionable nuclei

Nuclear fusion two isotopes (hydrogen) forced together at extremely high temperatures (100 million C) uncontrolled nuclear fusion thermonuclear weapons

1st Law of Energy or 1st Law of Thermodynamics in all physical and chemical changes energy is neither created or destroyed energy input always equal to energy output

2nd Law of Energy or 2nd Law of Thermodynamics when energy is changed from one form to another some of the useful energy is always degraded to lower quality, more dispersed, less useful energy(heat)

Implications for the environment – High waste society

Implications for the environment – Low waste society