Ch 2.1: What is Science? Chapter 2: Science, Matter, Energy, and Systems

Objectives Utilize the steps of the scientific method to conduct research Differentiate between theories and laws Identify limitations in science and research

Laws vs. Theories Scientific Law  Well tested widely accepted description of occurrences that happen over and over  Ex: Law of gravity  Scientific Theories  Overwhelming body of observation and measurements that support a hypothesis  Ex: Theory of Evolution

Science Is a Search for Order in Nature Identify a problem Find out what is known about the problem Ask a question to be investigated Gather data Hypothesize Make testable predictions Keep testing and making observations Accept or reject the hypothesis Peer Review

Scientists Use Reasoning, Imagination, and Creativity to Learn How Nature Works Inductive ReasoningDeductive Reasoning Specific observations, measurements General conclusion “bottom-up” or specific to general Ex: All swans we have seen have been white; therefore all swans are white. Logic, generalizations “top down” or general to specific Ex: All dogs are mammals. All mammals have kidneys. Therefore all dogs have kidneys.

Now what…the results Tentative science or frontier science Preliminary results Controversial Ex: Global Warming Reliable Science Based on ample data, hypothesis, theories, laws Peer reviewed Unreliable Science Not reviewed Bias

What are some limitations to science? 1. Scientists can disprove some things but they cannot prove anything absolutely due to uncertainty 2. Scientists cannot be unbiased but can minimize bias via peer review 3. Use of statistical tools and estimates 4. Involve many variables

Ch 2.2: What is Matter?

Concept 2-2 Matter consists of elements and compounds, which are in turn made up of atoms, ions, or molecules.

Matter Consists of Elements and Compounds 2. Matter Has mass and takes up space 3. Elements Unique properties Building blocks of any substance Cannot be broken down chemically into other substances Compounds Two or more different elements bonded together in fixed proportions

3. Atoms, Ions, and Molecules Are the Building Blocks of Matter (1) Atom--basic unit of matter Ion: electrically charged atom Molecule: combination of 2+ atoms/ions held together by chemical bonds

#4 Protons — positive, nucleus Neutrons — neutral, nucleus Electrons — negative, orbits

Matter Parts of Atoms Protons and Neutrons Major part of atom’s mass and 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)

Atomic Number Number of protons in nucleus Mass number Protons plus neutrons in nucleus Isotopes Element with same atomic number but different mass number Nonradioactive carbon-12 6 electrons 6 protons 6 neutrons Nonradioactive carbon-13 6 electrons 6 protons 7 neutrons Radioactive carbon-14 6 electrons 6 protons 8 neutrons

Matter Elements Element-pure substance that consists of just one type of atom 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 C Carbon

Ions Gain or lose electrons Nonmental: gain electrons, become more - Metal: lose electrons, become more + Form ionic compounds 5. Atoms, Ions, and Molecules Are the Building Blocks of Matter (1)

pH Measure of acidity H + and OH -

Chemical Formulas

Atoms, Ions, and Molecules Are the Building Blocks of Matter (3)

Bonding Ionic compounds are made up of oppositely charged ions Ex: Na+ and Cl- Compounds of uncharged atoms (shared) are covalent compounds CH 4

#8-9. Organic Compounds Are the Chemicals of Life Organic compounds At least 2 C atoms with 1 or more other atoms Hydrocarbons and chlorinated hydrocarbons Ex: methane (CH 4 ), DDT (C 14 H 9 Cl 5 ) Simple carbohydrates (C, H, O) Ex: Glucose (C 6 H 12 O 6 Macromolecules: complex organic molecules Complex carbohydrates, Proteins, nucleic acids, Lipids

Polymers Larger and more complex compounds that have molecular subunits Carbohydrates (sugar, starches): sugar subunits link Proteins (meats, enzymes): amino acid subunits link Nucleic acids (DNA or RNA) : nucleotides link

Matter Comes to Life through Genes, Chromosomes, and Cells Genes: sequences of nucleotides within the DNA give rise to traits Chromosomes: composed of many genes that are packaged DNA Genome: complete DNA sequence of base pairs that combine to make chromosomes in each individual species

Inorganic Compounds No C-C bonds Earth’s crust is mostly inorganic minerals and rock (Si & O) Various combinations of only eight elements make up the bulk of most minerals.

Fig. 2-5, p. 38 A human body contains trillions of cells, each with an identical set of genes. Each human cell (except for red blood cells) contains a nucleus. 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.

Some Forms of Matter Are More Useful than Others High-quality matter Highly concentrated, near earth’s surface, great potential as a resource Low-quality matter Not concentrated, deep underground resources, little potential for human use Aluminum can High Quality Solid Salt Coal Gasoline Aluminum ore Low Quality Solution of salt in water Gas Coal-fired power plant emissions Automobile emissions

When matter undergoes a physical or chemical change, no atoms are created or destroyed Ch 2.3: How Can Matter Change?

Law of Conservation of Matter Physical or chemical changes can’t create or destroy but only rearrange atoms No “away”!!!! -Law tells us there will always be wastes and pollutants

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

Chemical Changes Reactant(s) carbon + oxygen C + O 2 CO 2 + energy carbon dioxide + energy + energy Product(s) black solidcolorless gas C O O OOC

Nuclear Changes Matter can undergo physical, chemical OR nuclear changes Nuclear change--nucleus of certain isotopes spontaneously change or are made to change into nuclei of different isotopes Matter  Energy 3 types of nuclear change Radioactive decay Nuclear fission Nuclear fusion

Nuclear Changes Radioactive Decay Radioactive isotopes with unstable nuclei decay Gamma rays Genetic damage to DNA Somatic damage to tissues

Radioactive Isotopes Matter Elements Radioactive Isotopes Radioactive isotopes decay at a characteristic fixed rate called a half-life (t 1/2 ) Beneficial uses: C-14 dating can help geologists date fossils Cancer treatment U-235 in nuclear reactors

Table 3-1 Half-Lives of Selected Radioisotopes Isotope Potassium-42 Iodine-131 Cobalt-60 Hydrogen-3 (tritium) Strontium-90 Carbon-14 Plutonium-239 Uranium-235 Uranium-238 Radiation Half-Life 12.4 hours 8 days 5.27 years 12.5 years 28 years 5,370 years 24,000 years 710 million years 4.5 billion years Emitted Alpha, beta Beta, gamma Beta Alpha, gamma

Nuclear Changes Nuclear Fission Fission—splitting of atoms Nuclei of isotopes with large masses split into lighter nuclei when struck by neutrons Release energy and more neutrons setting off a chain reaction Atomic bomb and nuclear power plants

Fission fragment Energy n n n n Uranium-235 nucleus Unstable nucleus Energy

n U Kr Ba n n n Kr U U Ba Kr Ba Kr Ba n n n n n n n n U U U U n

Nuclear Changes Nuclear Fusion Fusion—joining atoms Isotopes of light elements are forced together at high T’s until they fuse into a heavier nucleus Harder to accomplish than fission, but releases more energy Fusion of H nuclei to form He nuclei is a source of energy for sun and stars

FuelReaction ConditionsProducts D-T Fusion Hydrogen-2 or deuterium nucleus Hydrogen-3 or tritium nucleus + + Neutron Energy + + Helium-4 nucleus million ˚C Neutron Proton +

The Laws of Thermodynamics Chapter 2.4: What is Energy and How Can It Be Changed?

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 1 o C Work is movement of matter (pump gas through pipe, move book) ESRT Specific Heat…

Energy Two types Kinetic Energy in motion Potential Stored energy Potential to be changed into kinetic energy

Energy Electromagnetic radiation Two types of EM radiation Ionizing EM radiation High energy  knock 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.

Energy Heat Heat- total kinetic energy of all moving atoms, ions or molecules Temperature—average speed of motion of the atoms, ions or molecules in matter Heat energy flows hot  cold Hot air/water less dense so rises.

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 Laws 1 st Law of Thermodynamics 1 st 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

Energy Laws 2 nd Law of Thermodynamics 2 nd Law of Thermodynamics (Law of disorder) When energy changed from one form to another, useful energy is degraded to lower quality, more dispersed, less useful energy Light bulb---95% lost as waste heat Energy stored in food---most lost as waste heat **We can never recycle or reuse high- quality energy to perform useful work

Solar energy Waste heat Chemical energy (photosynthesis) Waste heat Waste heat Waste heat Chemical energy (food) Mechanical energy (moving, thinking, living)

Matter and Energy Laws Environmental Problems Law of conservation of matter and 1 st and 2 nd law of thermodynamics together mean individual resource use adds waste matter and heat to the environment US 16% energy performs useful work, 41% lost as heat, 43% lost unnecessarily

Do Now: 1. What happens when you overheat? Why does this happen? 2. Who is at a higher risk for lung cancer…a miner, a smoker, a miner who smokes? Why? Ch 2.5 What are systems and how do they respond to change

2-5 What Are Systems and How Do They Respond to Change? Concept 2-5A Systems have inputs, flows, and outputs of matter and energy, and their behavior can be affected by feedback. Concept 2-5B Life, human systems, and the earth’s life support systems must conform to the law of conservation of matter and the two laws of thermodynamics.

Systems Have Inputs, Flows, and Outputs System- set of components that interact Inputs from the environment Flows, throughputs of matter & energy Outputs to environment

High-throughout Economy Matter and Energy Laws Environmental Problems High-throughout Economy Developed countries with ever increasing growth Increased one-way flow of matter through systems and out to planetary “sinks”--air, water, soil, and organisms Pollutants and wastes accumulate Output will exceed environment’s capacity to dilute and degrade waste matter and absorb heat UNSUSTAINABLE!

Low-Throughout Economy Matter and Energy Laws Environmental Problems Low-Throughout Economy Decrease matter and energy flow Don’t waste matter and energy resources Recycle and reuse Stabilize population

Core Case Study: Carrying Out a Controlled Scientific Experiment F. Herbert Bormann, Gene Likens, et al.: Hubbard Brook Experimental Forest in NH (U.S.) Compared the loss of water and nutrients from an uncut forest (control site) with one that had been stripped (experimental site)

Watershed The drainage basin that includes a major river and all of its tributaries Tributary Smaller rivers & streams that feed into larger rivers

What did they find? Deforested valley  30-40% increase in water flow  Increased Erosion  Increased Nutrient loss

Loss of NO 3 − from a Deforested Watershed

Systems Respond to Change through Feedback Loops Positive feedback loop Causes changes in system in same direction Ex: Hubbard Brook (deforestation, loss of nutrients) Ex: melting of polar ice caps (increasing temps, increasing melting, water absorbs more heat than ice…)

Negative, or corrective, feedback loop Changes in opposite direction Thermostat Ex: recycling of aluminum cans and reduction of mining How could Hubbard Brook scientists employed a negative feedback loop?

Time Delays Can Allow a System to Reach a Tipping Point Time delays vary Between the input of a feedback stimulus and the response to it Reforestation effects Tipping point, threshold level Causes a shift in the behavior of a system Can’t “rebound” Ex: population growth, toxic waste dumps leaking, global climate change

System Effects Can Be Amplified through Synergy Synergistic interaction, synergy Two or more processes interact so the combined effect is greater than sum of their parts Helpful Group dynamics vs. individuals for laws and regulations Harmful E.g., Smoking and inhaling asbestos particles

Human Activities Can Have Unintended Harmful Results Deforested areas turning to desert Coral reefs dying Glaciers melting Sea levels rising