APES Chapter #3 Science, System, Matter and Energy
Nature of Science • Science- an organized way of using evidence to learn about the natural world • Observations • Hypothesis • Experiment • Results • Conclusion
Scientific MethodObservations and Hypothesis • 1.Observations/Questions • What you see • Inferences-logical interpretations of what you see. • Questions then arise……. • 2.Hypothesis-scientific and testable explanation for observations • “If……then……”
Scientific MethodExperimental Procedure • 3.Experimental procedure- test the hypothesis • Must be controlled, reproducible Testing effects of only one variable (factor in experiment that is subject to change) Other scientists need to be able to reproduce and prove valid.
Scientific MethodExperimental Procedure • Subjects you are testing are split into groups: • Experimental Group-given the experimental factor • Control Group:-what you’re comparing experimental group to. Experimental Group Fertilizer Control Group No Fertilizer
Scientific MethodExperimental Procedure • Testing ONE variable while keeping others the same • Independent (manipulated) variable- factor in experiment that’s purposely changed—???? • Dependent (responding) variable —factor that a scientist observes for responses (changes) in—????
Scientific MethodResults and Conclusion • 4. Results • Record data—tables, graphs • Qualitative data- physical traits (qualities) described • Quantitative data- measurements (quantities) • 5.Conclusions • Hypothesis is either supported or rejected. NEVER “PROVEN!” • Can be partly true • Findings always useful!!!
Scientific MethodHypothesis vs. Theory • Hypothesis- educated, testable explanation for an observation • Theory • Verified, credible and widely accepted hypothesis • Make future predictions • Law- mathematical description of what a theory explains
Models and Behavior of SystemsSystem • Scientists determine the behavior of a system by developing a model of it in regards to matter and energy • Set of components that function and interact in regular, understandable way Throughputs(rates of flow) Outputs(to environment) Inputs(from environment) Energy Heat Human Body(inputs may be stored for different lengths of time) Ideas and actions Information Waste and pollution Matter
Models and Behavior of SystemsFeedback Loops • Feedback loops are found in a system • Output fed back into system leads to changes • Positive feedback- AMPLIFICATION • i.e. global warming • Negative feedback- CORRECTIVE • System changes in opposite direction • i.e. thermostat in house • crime and punishment
Models and Behavior of SystemsTime Delays and Synergy • Time delays -delay b/t input and output • Allows problems to build slowly so corrective action may come too late • i.e. smoking and population • Synergy- 2 or more processes interact so their combined effect is > than the sum of separate effects • i.e. drugs and alcohol, people picking up object
MatterAtoms • Matter-anything that has mass and takes up space • Atom--basic unit of matter • Protons—positive, nucleus • Neutrons—neutral, nucleus • Electrons—negative, orbits
MatterParts of Atoms • Protons and Neutrons • Together make up an atom’s atomic mass. • Electrons • 1/1840 of the mass of p’s and n’s • Moving in orbitals surrounding the nucleus • Responsible for chemical properties of atoms (how they react) • Atoms--Something to Think About!
MatterElements • Element-pure substance that consists of just one type of atom • 114 in the periodic table • Atoms have a one or two letter symbol • Atomic number • Unique to that element • #p’s-- and b/c normally atoms are uncharged also = # e’s • Atomic mass • How much mass an atom has • #p’s + #n’s 6 C Carbon 12.011
MatterIsotopes 6 Isotopes-atoms of the same element with different # of neutrons Atomic number same, atomic mass different Isotopes of Carbon Nonradioactive carbon-13 Radioactive carbon-14 Nonradioactive carbon-12 6 electrons 6 protons 6 neutrons 6 electrons 6 protons 7 neutrons 6 electrons 6 protons 8 neutrons
MatterRadioactive Isotopes • Radioactive isotopes- atoms with unstable nuclei • Break down at constant rate and can give off dangerous radiation (type of energy) • Beneficial uses: • C-14 dating can help geologists date fossils • Cancer treatment • U-235 in nuclear reactors
MatterBonding • Bonding- atoms gain, lose, or share e’s to be stable • Compound- formed by chemical combination of 2 or more elements • Bond formation involves outermost e’s • Two types of bonds • Ionic • Covalent
Chemical Bonds • Ionic bonds • Ionic bond -one or more e’ are transferred • Results in formation of ions, or charged atoms that attract to form an ionic compound Chloride ion (Cl-) Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na+) Transfer of electron Protons +11 Electrons -11 Charge 0 Protons +17 Electrons -17 Charge 0 Protons +11 Electrons -10 Charge +1 Protons +17 Electrons -18 Charge -1
Chemical BondsCovalent Bonds • Covalent bonds- formed by atoms sharing valence electrons • Stronger than ionic bonds • Molecule--forms when atoms are joined in a covalent bond
Compounds • Organic- contain C-C bonds • Can also have H, O, P, S, N and others • Natural or synthetic • Inorganic- don’t have C-C or C-H covalent bonds • NaCl, H2O C C
Organic Compounds • Some simple organic molecules can link up, forming C—C bonds- polymerization • Amino acids Proteins (meats, enzymes) • Fatty Acids and glycerol Lipids (fats, oils) • Sugars Carbohydrates (sugar, starches) • Nucleotides Nucleic acids (DNA or RNA)
Inorganic Compounds • No C-C bonds • Earth’s crust is mostly inorganic minerals and rock • Various combinations of only eight elements make up the bulk of most minerals.
Four States of Matter • Differ in spacing and orderliness of atoms, ions or molecules • Solid • Liquid • Gas • Plasma • Most abundant of all states of matter! • Forms when enough energy applied to strip away e’, so it’s a mixture of ions and e’ • Natural forms: sun, stars, lightning and flame • Artificial forms: TV, neon signs
Matter Quality • High quality • Easily accessible • High concentration • Great potential for use as resource • Low quality • Deep underground or difficult to collect • Low concentration • Low potential as a resource
High Quality Low Quality Gas Solid Salt Solution of salt in water Coal Coal-fired power plant emissions Gasoline Automobile emissions Aluminum can Aluminum ore
Law of Conservation of Matter • Physical changes in matter • Molecules organized differently but no change in chemical composition • Cutting foil, melting water • Chemical changes • Bonds made or broken • Burning coal, rusting
ChemicalChanges Reactant(s) Product(s) carbon + oxygen carbon dioxide+ energy C + O2 CO2+ energy O C O C O + energy O black solid colorless gas colorless gas
Law of Conservation of Matter • Law of Conservation of Matter- physical or chemical changes can’t create or destroy the atoms involved. They’re just rearranged • Chemical equations must be balanced • No “away”!!!! -Law tells us there will always be wastes, pollutants, and toxins
Toxicology Toxicology -the study of the adverse effects of chemicals or pollutants on living organisms’ health, specifically humans. Toxicity -a measure of how harmful a substance is and it depends on: -Amount of a potentially harmful substance that is ingested, inhaled, or absorbed through the skin is called the dose -Frequency of exposure -Who is exposed (adult or child) -How well the body’s detoxification system (liver, kidneys, etc.) work © Brooks/Cole Publishing Company / ITP
Toxicology The resulting type and amount of damage to health arecalled the response Two types of responses: • Acute- immediate or rapid harmful reaction (dizziness, rash, death) • Chronic- permanent or long–lasting consequence (asthma, kidney damage, heart disease)
Toxicology Factors • Six major characteristics of a substance determines its toxicity: • 1. Concentration • 1ppm= 1 part pollutant per million parts of gas, solid or liquid it is in • Can ↓ pollutant concentration by dumping in larger volume, but there are limits • 2. Solubility • Water-soluble- move through the environment and get in the water supply • Fat-soluble- penetrate cell membranes and accumulate in body tissue
Toxicology Factors • 3. Persistence • Some chemicals are resistant to breakdown so have long-lasting harmful effects • Degradable (nonpersistent)—broken down by natural, physical, chemical or biological processes • Biodegradable—broken down by living organisms • Slowly degradable (persistent) • Decades • Plastics, DDT • Nondegrading—lead, mercury, arsenic
Toxicology Factors • 4. Bioaccumulation results when the concentration of a chemical in tissues of an organism is higher than would normally be expected. • 5. Biomagnification involves magnification of concentrations as they pass through the food chains and webs. © Brooks/Cole Publishing Company / ITP
Toxicology Factors • 6. Chemical Interactions • Antagonistic interactions reduce harmful effects • Vitamin A, D and E apparently reduce some cancer-causing chemicals • Synergistic interactions multiplies harmful effects • Asbestos workers have a 20-fold increased chance of getting lung cancer, but if they smoke they have a 400-fold increase
Determining Toxicity • Determining toxicity: • Case reports (usually to physicians) • Epidemiology- studies of populations exposed • Laboratory investigations (usually with test animals) • LD50 (median lethal dose) -amt of a chemical that kills 50% of animals (rats) in a test population (60–200 animals) in 2 weeks • A poison is legally defined as a chemical that has an LD50≤50 mg chemical/kg body weight • ***Higher LD50, less toxic the substance is
Toxicity ToxicityLD50Lethal DoseExamples Super < 0.01 less than 1 drop dioxin, botulism mushrooms Extreme <5 less than 7 drops heroin, nicotine Very 5-50 7 drops to 1 tsp. morphine, codeine Toxic 50-500 1 tsp. DDT, H2SO4, Caffeine Moderate 500-5K 1 oz.-1 pt. aspirin, wood alcohol Slightly 5K-15K 1 pt. ethyl alcohol, soaps Non-Toxic >15K >1qt. water, table sugar ***Higher LD50, less toxic the substance is (LD50 measured in mg/kg of body weight)
Dose–Response Curves Dose–response curves- show the adverse effects of various doses of a toxic agent on a test population by plotting harmful effect as a function of dose. The left dose–response curve shows increasing harmful effects with dose, and no dose is considered safe. The right example has a threshold, such that low doses are considered safe. © Brooks/Cole Publishing Company / ITP
Toxicity • Why so little is known of toxicity • Only 10% of at least 75,000 commercial chemicals have been screened • ~2% determined to be carcinogen, teratogen or mutagen • >1000 new synthetic chemicals added per year • >99.5% of US commercial chemicals are NOT regulated
Chemical Hazards • What are toxic vs. hazardous chemicals? • Toxic (poisonous) chemicals- substances that are fatal to over 50% of test animals (LD50) at given concentrations • Hazardous chemicals- cause harm by • Flammable or explosive (e.g., gasoline) • Irritating or damaging the skin or lungs (e.g., strong acids or alkalines such as oven cleaners) • Interfering with or preventing oxygen uptake and distribution (e.g., carbon monoxide, CO) • Inducing allergic reactions © Brooks/Cole Publishing Company / ITP
Hazardous chemicals • Mutagens- cause random mutations, or changes in the DNA • Teratogens- cause birth defects • e.g., PCBs, steroid hormones, heavy metals, rubella, mercury in water, fetal alcohol syndrome and crack babies • Carcinogens- cause cancer • over 100 types of cancer (depending on cells involved) • e.g., cigarette smoke. • Hormone disrupters © Brooks/Cole Publishing Company / ITP
Hormone Disrupters Hormones -molecules that act as messengers in the endocrine system to regulate reproduction, growth and development. Hormone disrupters (mimics and blockers), attach to receptors and disrupt/alter development. © Brooks/Cole Publishing Company / ITP
Hormone Disrupters • 51 chemicals, many widely used, have been shown to be hormone disrupters on wildlife, laboratory animals and humans • i.e. dioxins, certain PCBs, various chemicals in plastics, some pesticides, lead and mercury • 1997 study shows that sperm count of men in U.S. and Europe has declined 50%. © Brooks/Cole Publishing Company / ITP
Energy • Energy- capacity to do work and transfer heat • Measured in calories = amt of heat required to raise the temp of 1.0g of water 1oC • Work is movement of matter (pump gas through pipe, move book)
Energy • Two types • Kinetic • Energy in motion • Possessed by matter b/c of its mass and speed (velocity) • Potential • Stored energy • Potential to be changed into kinetic energy • Rock in hand, unlit match, energy stored in bonds of foodstuff, water behind dam
EnergyElectromagnetic radiation Sun High energy, short wavelength Low energy, long wavelength Nonionizing radiation Ionizing radiation Visible Cosmic rays Far ultraviolet waves Near ultraviolet waves Near infrared waves Far infrared waves Gamma rays TV waves Radio waves X rays Microwaves 10-14 10-12 10-8 10-7 10-6 10-5 10-3 10-2 10-1 1 • Electromagnetic radiation (EM)- energy traveling in waves as • a result of changing electric and magnetic fields • Different forms with different wavelengths and energy content • Electromagnetic Radiation Movie
EnergyElectromagnetic radiation • Two types of EM radiation • Ionizing EM radiation • High energyknock e’s from atoms and change them to + ions • e’s and ions disrupt living cells-cancer • Non-ionizing EM radiation • Low energy Not highly reactive or as dangerous. • Visible light-- makes up most of the spectrum of EM radiation from the sun.
EnergyHeat • Heat- total kinetic energy of all moving atoms, ions or molecules • Temperature—average speed of motion of the atoms, ions or molecules in matter • Atoms move faster when heated • Heat energy flows hot cold • Hot air/water less dense due to energy so rises.
Energy Quality • Energy quality- measure of energy source’s ability to do useful work • High quality • Concentrated • Can perform much useful work • Chemical energy in coal and gas, sunlight • Low quality • Dispersed • Little ability to do work • Heat in atmosphere or heat in oceans
Energy Laws1st Law of Thermodynamics • 1st law of thermodynamics (Law of conservation of energy) • In all physical and chemical changes, energy is not created or destroyed, but changes form • Total energy of system remains constant