Science, Systems, Matter, and Energy Ch 2

A. The Nature of Science Science assumes that events in the natural world follow orderly patterns and that these patterns can be understood Based on observations of phenomenon, scientists form a scientific hypothesis Hypothesis — an unconfirmed explanation of an observed phenomenon to be tested A scientific theory is a verified, believable, widely accepted scientific hypothesis or a related group of scientific hypotheses

Scientists use both inductive reasoning and deductive reasoning Theories are the most reliable knowledge we have about how nature works A scientific/natural law describes events/actions of nature that reoccur in the same way, over and over again They always include a degree of uncertainty. Scientists use both inductive reasoning and deductive reasoning Inductive reasoning uses specific observations and measurements to arrive at a conclusion Deductive reasoning uses logic to arrive at a specific conclusion

Stepped Art Ask a question Do experiments and collect data Interpret data Well-tested and accepted patterns In data become scientific laws Formulate hypothesis to explain data Do more experiments to test hypothesis Revise hypothesis if necessary Well-tested and accepted hypotheses become scientific theories Stepped Art Fig. 2-3, p. 30

Frontier science is scientific results that have not been confirmed; Sound science results from scientific results that have been well tested and are widely accepted. Media people mislead us, consider the reliability of the individuals presenting the data.

B. Models and Behavior of Systems Scientists project the behavior of complex systems by developing a model of its inputs, throughputs (flows), and outputs of matter, energy, and information. Mathematical models consist of one or a series of equations used to describe behavior of a system (e.g. Hurricane behavior)

Sustainable low-waste economy Matter Feedback Energy Feedback Inputs (from environment) System Throughputs Outputs (into environment) Energy Conservation Low-quality Energy (heat) Energy Sustainable low-waste economy Waste and pollution Waste and pollution Pollution control Matter Recycle and reuse Matter Feedback Figure 2.16 Solutions: lessons from nature. A low-throughput economy, based on energy flow and matter recycling, works with nature to reduce the throughput of matter and energy resources (items shown in green). This is done by (1) reusing and recycling most nonrenewable matter resources, (2) using renewable resources no faster than they are replenished, (3) using matter and energy resources efficiently, (4) reducing unnecessary consumption, (5) emphasizing pollution prevention and waste reduction, and (6) controlling population growth. Energy Feedback Fig. 2-16, p. 47

Feedback loops can cause a system to do more positive feedback (what it was doing) or negative feedback (in opposite direction)

Animation: Feedback Control of Temperature PLAY ANIMATION

A synergistic interaction results in the combined effects interact to amplify the results smoking magnify the effect of asbestos exposure on lung cancer

C. Types and Structure of Matter Matter is anything that has mass and takes up space Elements (represented on the periodic table) are the distinctive building blocks of matter Compounds: two or more different elements held together in fixed proportions by chemical bonds

The building blocks of matter are atoms Each atom has a nucleus containing protons and neutrons and one or more electrons orbit the nucleus. A proton (p) is positively charged. A neutron (n) is uncharged. The electron (e) is negatively charged Isotopes of an element are various forms of an element that have the same atomic number, but different mass number. May need to show the difference in atomic number versus atomic mass i.e. Carbon is #6 but mass is 12 and it’s isotope is mass of 14 a two neutron difference.

Atoms Figure 2-4

Animation: Subatomic Particles PLAY ANIMATION

Animation: Atomic Number, Mass Number PLAY ANIMATION

An ion is an atom or group of atoms with one or more net positive or negative electrical charges. e.g. Hydrogen ions (H+), Hydroxide ions (OH- ) Elements known, as metals tend to lose one or more electrons Elements known, as nonmetals tend to gain more electrons

Animation: Ionic Bonds PLAY ANIMATION

Hydrogen ions (H+) in a solution are a measure of how acidic or basic the solution The amount of a substance in a unit volume of air, water, or other medium is its concentration The pH (potential of Hydrogen) is the concentration of hydrogen ions in one liter of solution

Figure 2-5

Animation: pH Scale PLAY ANIMATION

Chemical formulas are a type of shorthand to show the type and number of atoms/ions in a compound Ionic compounds are made up of oppositely charged ions, (Na+ and Cl-). Compounds made of uncharged atoms are called covalent compounds (CH4).

Organic compounds contain carbon atoms combined with one another and with various other atoms such as H+, N+, or Cl-. Contain at least two carbon atoms combined with each other and with atoms. Methane (CH4) is the only exception. All other compounds are inorganic. Hydrocarbons: compounds of carbon and hydrogen atoms Chlorinated hydrocarbons: compounds of carbon, hydrogen, and chlorine atoms Simple carbohydrates: specific types of compounds of carbon, hydrogen and oxygen atoms. (e.g. sugars)

Animation: Carbon Bonds PLAY ANIMATION

Large, complex organic molecules (macromolecules) make up the basic molecular units found in living organisms; four major types: Complex carbohydrates contain two or more monomers of simple sugars Proteins are formed by linking monomers of amino acids Nucleic acids are made of sequences of nucleotides Lipids large organic compounds that are non-polar ex; fats, oils, steroids, and hormones.

All living things are composed of cells Cells of eukaryotic organisms have a membrane, nucleus, and organelles Cells of prokaryotic organisms have a membrane but no defined nucleus or organelles Organic molecules are the building blocks of life

Animation: Prokaryotic and Eukaryotic Cells PLAY ANIMATION

Matter exists in four states, solid, liquid, gaseous and as plasma Water can exist in all three forms Plasma is a high-energy mixture of positively charged ions and negatively charged electrons. Scientists make artificial plasmas in fluorescent lights, TV and computer screens.

Matter can be classified as having high or low quality depending on how useful it is to us as a resource. High quality matter is concentrated and easily extracted. low quality matter is more widely dispersed and more difficult to extract. Figure 2-8

Material efficiency/resource productivity describes the total amount of material needed to produce a unit of good/service.

D. Changes in Matter The Law of conservation of matter states that no atoms are created/destroyed during a physical or chemical change In a physical change, the molecules are organized in different patterns. In a chemical change, the chemical composition of the elements/compounds change Chemical equations are used to verify that no atoms are created or destroyed in a chemical reaction

Changes in Matter 3 minutes

Reactant(s) Product(s) energy energy energy carbon carbon dioxide + oxygen + C + O2 CO2 + energy + + energy black solid colorless gas colorless gas p. 39

Pollutants are classified based on their persistence: We will always have some pollutants, but can produce less and clean up some that we do produce Factors that determine the severity of a pollutant’s effects: chemical nature, concentration, and persistence. Pollutants are classified based on their persistence: Degradable pollutants Biodegradable pollutants Slowly degradable pollutants Nondegradable pollutants

Three types of nuclear change are radioactive decay, nuclear fission, and nuclear fusion. Radioactive decay is the change of a radioisotope to different isotope by spontaneously emitting fast moving chunks of matter The rate of decay is expressed as a half-life (the time needed for one-half of the nuclei to decay to form a different isotope) Exposure to ionizing radiation from this damages cells in two possible ways: genetic damage (mutation of DNA molecules), body cell damage to tissues. Common half lives : Carbon14 5,760 yrs, U235 7.04 x 108 , Listing of Half-lifes; http://www.iem-inc.com/toolhalf.html

Animation: Half-Life PLAY ANIMATION

Nuclear Changes: Fission Nuclear fission: nuclei of certain isotopes with large mass numbers are split apart into lighter nuclei when struck by neutrons. Critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction. Figure 2-9

Stepped Art Fig. 2-6, p. 28 Uranium-235 Energy Fission fragment n Neutron Stepped Art Fig. 2-6, p. 28

Nuclear Changes: Fusion Nuclear fusion: two isotopes of light elements are forced together at extremely high temperatures until they fuse to form a heavier nucleus. Figure 2-10

Video: Nuclear Energy PLAY VIDEO From ABC News, Environmental Science in the Headlines, 2005 DVD.

E. Energy & Energy Laws: Energy is the capacity to do work and transfer heat; it moves matter Kinetic energy has mass and speed Potential energy is stored energy, ready to be used Potential energy can be changed to kinetic energy

Animation: Martian Doing Mechanical Work PLAY ANIMATION

Electromagnetic radiation is energy that travels as a wave, a result of changing electric and magnetic fields The electromagnetic spectrum describes the range of electromagnetic waves that have different wavelengths and energy content Organisms vary in there ability to sense different parts of the spectrum.

Original Energy Source

Solar ejection

Sun Ionizing radiation Nonionizing radiation Cosmic rays Gamma Rays Far ultra- violet waves Near ultra- violet waves Near infrared waves Far infrared waves X rays Visible Waves Micro- waves TV waves Radio Waves Figure 2.11 The electromagnetic spectrum: the range of electromagnetic waves, which differ in wavelength (distance between successive peaks or troughs) and energy content. High energy, short Wavelength Wavelength in meters (not to scale) Low energy, long Wavelength Fig. 2-11, p. 43

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The first law of thermodynamics: we cannot create or destroy energy. We can change energy from one form to another. The second law of thermodynamics: energy quality always decreases. When energy changes from one form to another, it is always degraded to a more dispersed form. Energy efficiency is a measure of how much useful work is accomplished before it changes to its next form.t

Animation: Total Energy Remains Constant PLAY ANIMATION

Mechanical energy (moving, thinking, living) Chemical energy (photosynthesis) Chemical energy (food) Solar energy Waste Heat Waste Heat Waste Heat Waste Heat Figure 2.14 The second law of thermodynamics in action in living systems. Each time energy changes from one form to another, some of the initial input of high-quality energy is degraded, usually to low-quality heat that is dispersed into the environment. Fig. 2-14, p. 45

F Sustainability and Matter and Energy Laws Resource use automatically adds some waste heat/waste to the environment Advanced industrialized countries have high-throughput (high waste) economies Eventually consumption will exceed capacity of the environment to dilute/degrade wastes Recycling and reusing more of earth’s matter resources slows depletion of nonrenewable resources,

Shifting to a more sustainable, low-throughput (low-waste) economy is the best long-term solution to environmental/resource problems Waste less matter, live more simply, slow population growth.