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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 worksTechnology – creation of new processes intended to improve the quality of life
Scientific methodHYPOTHESIS – proposed to explain observed patternsCritical experimentsAnalysis and conclusions
Scientific law and Theory
Law – certain phenomena always act in a predictable mannerTheory – rational explanation for numerous observations of a certain phenomena – global warming due to greenhouse effect
Accuracy Vs PrecisionAccuracy – measurement agrees with the accepted correct value
Precision – measure of reproducibility
Types of reasoning
Inductive - using observations and facts to arrive at generalizationsDeductive - using logic to arrive at a specific conclusion
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
Important Terms
Inputs - matter, energy, informationThroughput - flow of inputOutput - matter, energy, information flowing out
Matter and Energy Resources
Nature’s Building Blocksanything that has mass and takes up space
Forms of matter
elements – single type of atoms110 elements – 92 natural +18 synthesizedcompounds - 2 or more elements, held together by chemical bonds
Building Blocks
atoms - smallest units of matter- protons,neutrons,electronsion - electrically charged atomsmolecules - combinations of atoms of the same or different elements
Definitions
Atomic Number - number of protonsIsotopes - same atomic number, different mass numberIons - atoms can gain or lose one or more electronsMass 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 carbonsugar, vitamins, plastics, aspirin
Environmental Organic Compounds
Hydrocarbons = methane gasChlorinated hydrocarbons =. DDT, PCBChlorofluorocarbons (CFC)- Freon 12
Polymers
larger and more complex organic compounds made up of monomerscomplex carbohydratesproteins - 20 amino acidsnucleic acids - nucleotides
Inorganic compounds
no carbon,not originating from a living sourceEarth’s crust – minerals,waterwater, nitrous oxide, nitric oxide, carbon monoxide, carbon dioxide, sodium chloride, ammonia
Matter qualityMeasure 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 actionelectromagnetic radiation, heat, temperaturePotential energy - stored energy that is potentially available
Electromagnetic radiation
different wave lengths shorter – high energy, disrupts cells with long term exposure
Energy sources
97% solarwithout it earth’s temperature - 240 C1% - 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 destroyedno “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….radioisotopesEstimate age of rocks and fossilsTracers in pollution detection and medicineGenetic 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 Fissioncertain isotopes
(uranium 235) split apart into lighter nuclei when struck by neutronschain reaction releases energyneeds 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 destroyedenergy 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