Chemistry and bio apes ppt chaper 2Presentation Transcript
Chapter 2 Science, Systems, Matter, and Energy
Chapter Overview Questions What is science, and what do scientists do? What are major components and behaviors of complex systems? What are the basic forms of matter, and what makes matter useful as a resource? What types of changes can matter undergo and what scientific law governs matter?
Chapter Overview Questions (cont’d) What are the major forms of energy, and what makes energy useful as a resource? What are two scientific laws governing changes of energy from one form to another? How are the scientific laws governing changes of matter and energy from one form to another related to resource use, environmental degradation and sustainability?
Updates Online The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles. InfoTrac: Underwater Microscope Finds Biological Treasures in Subtropical Ocean. Ascribe Higher Education News Service, June 26, 2006. InfoTrac: In Bacterial Diversity, Amazon Is a 'Desert'; Desert Is an 'Amazon'. Ascribe Higher Education News Service, Jan 9, 2006. InfoTrac: Making MGP wastes beneficial. Bob Paulson. Pollution Engineering, June 2006 v38 i6 p20(5). NASA: Nitrogen Cycle Environmental Literacy Council: Phosphorous Cycle National Sustainable Agriculture Information Service: Nutrient Cycles
Video: The Throw Away Society This video clip is available in CNN Today Videos for Environmental Science, 2004, Volume VII. Instructors, contact your local sales representative to order this volume, while supplies last.
Core Case Study: Environmental Lesson from Easter Island Thriving society 15,000 people by 1400. Used resources faster than could be renewed By 1600 only a few trees remained. Civilization collapsed By 1722 only several hundred people left. Figure 2-1
THE NATURE OF SCIENCE What do scientists do? Collect data. Form hypotheses. Develop theories, models and laws about how nature works. Figure 2-2
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 Fig. 2-2, p. 29
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
Scientific Theories and Laws: The Most Important Results of Science Scientific Theory Widely tested and accepted hypothesis. Scientific Law What we find happening over and over again in nature. Figure 2-3
Research results Scientific paper Peer review by experts in field Paper rejected Paper accepted Paper published in scientific journal Research evaluated by scientific community Fig. 2-3, p. 30
Testing Hypotheses Scientists test hypotheses using controlled experiments and constructing mathematical models. Variables or factors influence natural processes Single-variable experiments involve a control and an experimental group. Most environmental phenomena are multivariable and are hard to control in an experiment. Models are used to analyze interactions of variables.
Scientific Reasoning and Creativity Inductive reasoning Involves using specific observations and measurements to arrive at a general conclusion or hypothesis. Bottom-up reasoning going from specific to general. Deductive reasoning Uses logic to arrive at a specific conclusion. Top-down approach that goes from general to specific.
Frontier Science, Sound Science, and Junk Science Frontier science has not been widely tested (starting point of peer-review). Sound science consists of data, theories and laws that are widely accepted by experts. Junk science is presented as sound science without going through the rigors of peer-review.
Limitations of Environmental Science Inadequate data and scientific understanding can limit and make some results controversial. Scientific testing is based on disproving rather than proving a hypothesis. Based on statistical probabilities.
MODELS AND BEHAVIOR OF SYSTEMS Usefulness of models Complex systems are predicted by developing a model of its inputs, throughputs (flows), and outputs of matter, energy and information. Models are simplifications of “real-life”. Models can be used to predict if-then scenarios.
Feedback Loops: How Systems Respond to Change Outputs of matter, energy, or information fed back into a system can cause the system to do more or less of what it was doing. Positive feedback loop causes a system to change further in the same direction (e.g. erosion) Negative (corrective) feedback loop causes a system to change in the opposite direction (e.g. seeking shade from sun to reduce stress).
Feedback Loops: Negative feedback can take so long that a system reaches a threshold and changes. Prolonged delays may prevent a negative feedback loop from occurring. Processes and feedbacks in a system can (synergistically) interact to amplify the results. E.g. smoking exacerbates the effect of asbestos exposure on lung cancer.
TYPES AND STRUCTURE OF MATTER Elements and Compounds Matter exists in chemical forms as elements and compounds. 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.
Atoms Figure 2-4
Ions An ion is an atom or group of atoms with one or more net positive or negative electrical charges. The number of positive or negative charges on an ion is shown as a superscript after the symbol for an atom or group of atoms Hydrogen ions (H+), Hydroxide ions (OH-) Sodium ions (Na+), Chloride ions (Cl-)
The pH (potential of Hydrogen) is the concentration of hydrogen ions in one liter of solution. Figure 2-5
Compounds and Chemical Formulas Chemical formulas are shorthand ways to show the atoms and ions in a chemical compound. Combining Hydrogen ions (H+) and Hydroxide ions (OH-) makes the compound H2O (dihydrogen oxide, a.k.a. water). Combining Sodium ions (Na+) and Chloride ions (Cl-) makes the compound NaCl (sodium chloride a.k.a. salt).
Organic Compounds: Carbon Rules 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.
Organic Compounds: Carbon Rules Hydrocarbons: compounds of carbon and hydrogen atoms (e.g. methane (CH4)). Chlorinated hydrocarbons: compounds of carbon, hydrogen, and chlorine atoms (e.g. DDT (C14H9Cl5)). Simple carbohydrates: certain types of compounds of carbon, hydrogen, and oxygen (e.g. glucose (C6H12O6)).
Cells: The Fundamental Units of Life Cells are the basic structural and functional units of all forms of life. Prokaryotic cells (bacteria) lack a distinct nucleus. Eukaryotic cells (plants and animals) have a distinct nucleus. Figure 2-6
(a) Prokaryotic Cell DNA(information storage, no nucleus) Cell membrane (transport of raw materials and finished products) Protein construction and energy conversion occur without specialized internal structures Fig. 2-6a, p. 37
(b) Eukaryotic Cell Energy conversion Nucleus (information storage) Protein construction Cell membrane (transport of raw materials and finished products) Packaging Fig. 2-6b, p. 37
Macromolecules, DNA, Genes and Chromosomes Large, complex organic molecules (macromolecules) make up the basic molecular units found in living organisms. Complex carbohydrates Proteins Nucleic acids Lipids Figure 2-7
A human body contains trillions of cells, each with an identical set of genes. There is a nucleus inside each human cell (except red blood cells). Each cell nucleus has an identical set of chromosomes, which are found in pairs. A specific pair of chromosomes contains one chromosome from each parent. Each chromosome contains a long DNA molecule in the form of a coiled double helix. Genes are segments of DNA on chromosomes that contain instructions to make proteins—the building blocks of life. The genes in each cell are coded by sequences of nucleotides in their DNA molecules. Fig. 2-7, p. 38
A human body contains trillions of cells, each with an identical set of genes. There is a nucleus inside each human cell (except red blood cells). Each cell nucleus has an identical set of chromosomes, which are found in pairs. A specific pair of chromosomes contains one chromosome from each parent. Each chromosome contains a long DNA molecule in the form of a coiled double helix. Genes are segments of DNA on chromosomes that contain instructions to make proteins—the building blocks of life. The genes in each cell are coded by sequences of nucleotides in their DNA molecules. Stepped Art Fig. 2-7, p. 38
States of Matter The atoms, ions, and molecules that make up matter are found in three physical states: solid, liquid, gaseous. A fourth state, plasma, is a high energy mixture of positively charged ions and negatively charged electrons. The sun and stars consist mostly of plasma. Scientists have made artificial plasma (used in TV screens, gas discharge lasers, florescent light).
Matter Quality 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
Matter Quality It is the measure of how useful a form of matter is as a resource Based on AVAILABILITY and CONCENTRATION High Quality Easy to extract Found near earth’s surface Great potential for use as a material resource Low Quality Dilute Usually deep underground or dispersed in the ocean or atmosphere Has little potential for use as material resource
Aluminum Can A more concentrated, Higher Quality matter than aluminum ore that contains the same amount of aluminum Less energy, water and energy to recycle an aluminum can compared to making a brand new aluminum can
High Quality Low Quality Solid Gas Solution of salt in water Salt Coal Coal-fired power plant emissions Gasoline Automobile emissions Aluminum can Aluminum ore Fig. 2-8, p. 39
CHANGES IN MATTER Matter can change from one physical form to another or change its chemical composition. When a physical or chemical change occurs, no atoms are created or destroyed. Law of conservation of matter. Physical change maintains original chemical composition. Different spatial arrangement Chemical change involves a chemical reaction which changes the arrangement of the elements or compounds involved. Chemical equations are used to represent the reaction. Rearrangement of atoms
Chemical Change Energy is given off during the reaction as a product.
Reactant(s) Product(s) energy carbon dioxide carbon + oxygen + energy + O2 C CO2 + energy + + black solid colorless gas colorless gas p. 39
Types of Pollutants Factors that determine the severity of a pollutant’s effects: Chemical nature Concentration ppm-parts per million… One part pollutant to a million parts of liquid, gas, or solid mixture it is part of Persistence How long it stays in water, air, soil, body Pollutants are classified based on their persistence: Degradable pollutants Biodegradable pollutants Slowly degradable pollutants Nondegradable pollutants
Types of Pollutants Degradable pollutants Non - persistent Can be broken down completely or reduced to acceptable levels by natural physical, chemical or biological processes Biodegradable pollutants Complex chemicals that specialized living organisms (certain bacteria) can break down into simpler chemicals (ie human sewage) Slowly degradable pollutants Persistent pollutant that last for a decade or longer (ie DDT pesticide) Nondegradable pollutants Chemical that cannot be broken down by natural processes (lead, mercury, arsenic)
ENERGY Energy is the ability to do work and transfer heat. Kinetic energy – energy in motion heat, electromagnetic radiation Potential energy – stored for possible use batteries, glucose molecules
3 Ways Heat Can Be Transferred Convection When warmer particles rise and the fall as then cool down Conduction Particles move and transfer energy to particles around them, until they are all heated to the point where they are moving so fast they are too hot to touch Radiation When heat from the hot/heated material radiates to the surrounding air
Electromagnetic Spectrum Many different forms of electromagnetic radiation exist, each having a different wavelength and energy content. Figure 2-11
Sun Nonionizing radiation Ionizing radiation Near infrared waves Far infrared waves Near ultra- violet waves Far ultra- violet waves Cosmic rays Gamma Rays Visible Waves TV waves Radio Waves X rays Micro- waves High energy, short Wavelength Wavelength in meters (not to scale) Low energy, long Wavelength Fig. 2-11, p. 43
EM Spectrum Ionizing radiation Cosmic rays, gamma rays, X-rays, UV rays Contain enough energy to knock electrons off of atoms and create positively charged particles Result is highly reactive electrons and ions…DANGEROUS! Genetic damage Cause disruptions in DNA that is passed down to offspring Somatic damage Causes damage to tissue structure Burns, miscarriages, cataracts, cancers Nonionizing radiation Not enough energy to knock off electrons and create ions
Electromagnetic Spectrum Organisms vary in their ability to sense different parts of the spectrum. Figure 2-12
Energy emitted from sun (kcal/cm2/min) Visible Infrared Ultraviolet Wavelength (micrometers) Fig. 2-12, p. 43
Relative Energy Quality (usefulness) Source of Energy Energy Tasks Electricity Very high temperature heat (greater than 2,500°C) Nuclear fission (uranium) Nuclear fusion (deuterium) Concentrated sunlight High-velocity wind Very high-temperature heat (greater than 2,500°C) for industrial processes and producing electricity to run electrical devices (lights, motors) High-temperature heat (1,000–2,500°C) Hydrogen gas Natural gas Gasoline Coal Food Mechanical motion to move vehicles and other things) High-temperature heat (1,000–2,500°C) for industrial processes and producing electricity Normal sunlight Moderate-velocity wind High-velocity water flow Concentrated geothermal energy Moderate-temperature heat (100–1,000°C) Wood and crop wastes Moderate-temperature heat (100–1,000°C) for industrial processes, cooking, producing steam, electricity, and hot water Dispersed geothermal energy Low-temperature heat (100°C or lower) Low-temperature heat (100°C or less) for space heating Fig. 2-13, p. 44
ENERGY LAWS: TWO RULES WE CANNOT BREAK 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.
Laws of Thermodynamics Cannot create or destroy energy, only transfer or change form When energy changes form, some energy is always degraded to lower quality, more dispersed, less useful forms of energy (more useful to less useful)
Mechanicalenergy(moving,thinking,living) Chemical energy (photosynthesis) Chemical energy (food) Solar energy Waste Heat Waste Heat Waste Heat Waste Heat Fig. 2-14, p. 45
ISOTOPES! Atoms with the same atomic number but with different atomic masses are called isotopes Changing the # of neutrons in an atom will affect the… MASS NUMBER= protons + neutrons Isotopes of an element have the same # of p+ and e-…so they behave the same CHEMICALLY The average of all the mass #s of the isotopes of an element give us that decimal on the periodic table (Average Atomic Mass)
Radioactive Isotopes As the difference b/t p+ and n. in the nucleus increases, the nucleus becomes more unstable When p=n , nucleus is stable… When n>p or n<p, nucleus is unstable Nucleus will give off tiny amounts of energy to become stable (protons or neutrons) Radiation=energy Radioactive=when something gives off energy
Isotopes of the Element Potassium with a Known Natural Abundance Mass # Natural Abundance Half-life 39 93.2581% Stable 40 0.0117% 1.265×10+9 years 41 6.7302% Stable
Isotopes continued Radiation can be dangerous in large amounts but in small amounts it can be useful in science Geology-determine age of fossils and rocks Medicine-treat cancer and detect cell processes (tracers) PET scans, CT scans, MRI Commercial-kill bacteria that spoils certain foods
Nuclear Changes: Radioactive Decay Natural radioactive decay: unstable isotopes spontaneously emit fast moving chunks of matter (alphaorbeta particles), high-energy radiation (gamma rays), or both at a fixed rate. Radiation is commonly used in energy production and medical applications. 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).
Half-life (HL) Time needed for one-half of the nuclei to decay to form a different isotope Emits radiation to form different isotope Decay continues until stable nuclei is produced…forms various radioactive isotopes Each radioactive isotope has a characteristic HL HL cannot be changed by temperature, pressure, chemical rxns, or other known factors
Half Life continued Use HL to estimate how long a sample radioactive isotope must be stored in a safe container before it decays to what is considered a safe level General rule: takes about 10 half-lives to reach this “safe” level Radioactive Iodine-131 Concentrated in thyroid gland HL= 8 days How long to reach a safe level? 10 x 8 days = 80 days Radioactive Plutonium-239 Produced in nuclear reactors and used as explosive in nuclear weapons HL= 24,000 years How long to reach a safe level? 10 x 24,000= 240,000 years
Nuclear Changes: Fission Nuclear fission: nuclei of certain isotopes with large mass numbers are split apart into lighter nuclei when struck by neutrons. Figure 2-9
Uranium-235 Uranium-235 Uranium-235 Energy Fission Fragment Uranium-235 n n Neutron n n Uranium-235 Energy Energy n n Uranium-235 Fission Fragment Uranium-235 Energy Uranium-235 Uranium-235 Uranium-235 Fig. 2-9, p. 41
Uranium-235 Uranium-235 Uranium-235 Energy Fission fragment Uranium-235 n n n Neutron n Energy Energy Uranium-235 n Uranium-235 n Fission fragment Uranium-235 Energy Uranium-235 Uranium-235 Uranium-235 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
Reaction Conditions Products Fuel Proton Neutron Energy Hydrogen-2 (deuterium nucleus) + 100 million °C + Helium-4 nucleus + + Hydrogen-3 (tritium nucleus) Neutron Fig. 2-10, p. 42
SUSTAINABILITY AND MATTER AND ENERGY LAWS Unsustainable High-Throughput Economies: Working in Straight Lines Converts resources to goods in a manner that promotes waste and pollution. Figure 2-15
System Throughputs Inputs (from environment) Outputs (into environment) Unsustainable high-waste economy High-quality energy Low-quality energy (heat) Matter Waste and pollution Fig. 2-15, p. 46
Sustainable Low-Throughput Economies: Learning from Nature Matter-Recycling-and-Reuse Economies: Working in Circles Mimics nature by recycling and reusing, thus reducing pollutants and waste. It is not sustainable for growing populations.
Mechanicalenergy(moving,thinking,living) Chemical energy (photosynthesis) Chemical energy (food) Solar energy Waste Heat Waste Heat Waste Heat Waste Heat Fig. 2-14, p. 45
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 Energy Feedback Fig. 2-16, p. 47