Transcript Science
Science. Matter. Energy. Systems. Chapter 2 1 Important Definitions to Review Science – knowledge of how the world works Technology – creation of new processes intended to improve the quality of life 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 – measurement agrees with the accepted correct value Precision – measure of reproducibility Inductive reasoning- using observations and facts to arrive at generalizations Deductive reasoning - using logic to arrive at a specific conclusion 2 Scientific method identify question/problem HYPOTHESIS – proposed to explain observed patterns Complete experiment and collect data Analysis and conclusions (results tentative, reliable or unreliable) Experiments subject to peer review identify biases Identify limitations 3 Systems system: set of components that interact in some regular way Open system: systems the exchange both energy and matter across their boundaries most environmental systems open Inputs - matter, energy, information Throughput - flow of input Output - matter, energy, information flowing out Closed system: exchange energy but not matter across their boundaries ex. water cycle feedback loop: Change in one part of a system influences another part of the system 4 5 Positive feedback loop causes a system to change further in the same direction. (farther from normal) Exponential growth of population – more individuals lead to increased number of births Precipitation causes erosion. Erosion causes plants to die. More precipitation causes more erosion and more vegetation death. 6 Negative feedback loop system to change in the opposite direction from which it is moving (closer to normal) Temperature regulation in humans – increased temperature leads to decrease in temperature by sweating 7 Implications for the environment – High waste society 8 Implications for the environment – Low waste society 9 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 Can be beneficial or harmful Chaos – unpredictable behavior in a system 10 Matter and Energy Resources Nature’s Building Blocks anything that has mass and takes up space 11 Forms of matter elements – single type of atoms 110 elements 92 natural, 18 synthesized table 2.1 (important elements) compounds - 2 or more elements, held together by chemical bonds table 2.3 (important compounds) 12 Atomic Theory Definitions atoms - smallest units of matter- protons (+), neutrons (0), electrons (-) protons/neutrons in nucleus of atom atomic # = # of protons isotope: same atomic number but different mass number (different form of the same element) Carbon-14; Uranium-235 ion - electrically charged atoms Table 2.2 (important ions) molecules - combinations of atoms of the same or different elements 13 Some Important elements composition by weight – only 8 elements make up 98.5% of the Earth’s crust 14 Organic Compounds with 2 or more atoms of carbon hydrocarbons: carbon and hydrogen atoms methane CH4 (only exception to 2 C rule) Octane C8H18 chlorinated hydrocarbons: carbon, hydrogen and chlorine DDT C14H9Cl5 Simple carbohydrates: carbon, hydrogen and oxygen glucose C6H12O6 Also includes Polymers. complex carbohydrates (made of simple sugars), nucleic acids (made of nucleotides), proteins (made of amino acids) and lipids 15 Inorganic compounds no carbon, not originating from a living source Earth’s crust – minerals, water water, nitrous oxide, nitric oxide, sodium chloride, ammonia 16 Matter quality Measure of how useful a matter is for humans based on availability and concentration 17 Energy capacity to do work and transfer heat Kinetic Energy -energy in action electromagnetic radiation (energy in waves resulting from electrical/magnetic fields), heat (energy in moving atoms) Potential energy - stored energy that is potentially available; may be changed to kinetic 18 Electromagnetic radiation different wave lengths Shorter wavelength= high energy disrupts cells with long term exposure 19 Energy sources 99% of the energy that supports earth comes from the sun without it earth’s temperature -240 C or -400 F allows for wind, hydro and biomass sources of renewable energy 1% - commercial sources. Burning oil, coal and natural gas. 20 Energy quality Measure of how useful an energy source is in terms of concentration and ability to perform useful work 21 Energy Changes energy changes governed by 2 scientific laws law of conservation of energy (first law of thermodynamics) no energy is created or destroyed as it changes from one form to another energy input = energy output can lose energy quality (converted to a less useful form) second law of thermodynamics as energy changes form we end up with a lower quality or less usable energy source (heat) 22 Nuclear Changes nuclei of certain isotopes spontaneously change (radioisotopes) or made to change into one or more different isotopes Occurs with one of the following particles: Alpha particles – fast moving (2 protons+2 neutrons) Beta particles – high speed electrons Gamma particles - high energy electromagnetic radiation radioactive decay, nuclear fission, nuclear fusion 23 Use….radioisotopes Estimate age of rocks and fossils Tracers in pollution detection and medicine Genetic control of insects 24 Half – Life (radioactive decay) time needed for one-half of the nuclei in a radioisotope to decay and emit their radiation. ranges from fraction of a second to millions of years 25 certain isotopes (uranium-235) split apart into lighter nuclei + neutrons when struck by neutrons chain reaction releases energy Releases an enormous amount of energy very quickly Nuclear Fission 26 Nuclear fusion two isotopes (hydrogen) forced together at extremely high temperatures (100 million C) Fuse to form a heavy nucleus and release a tremendous amount of energy 27