Chapter 2: Science, Matter, Energy, and Systems

2.1 What is science?

Science Is a Search for Order in Nature * Science: Understanding how nature functions and then using that understanding to forecast what is likely to occur in nature. * Scientific Process: * Identify a problem * Find out what is known about the problem (literature search) * Ask a question to be investigated * Perform an experiment to answer the question and collect data * Analyze data (check for patterns) * Propose a hypothesis to explain the data * Use the hypothesis to make testable predictions * Perform an experiment to test predictions * Accept hypothesis * Revise hypothesis * Make testable predictions * Test prediction * Scientific Hypothesis * A possible or testable explanation. * Experiment * Tests are done under controlled conditions and can be used to gather information and test ideas. * Model * An approximate representation or simulation of a system being studied. * Scientific Theory: A well-tested and widely accepted scientific hypothesis or a group of related hypotheses * Peer Review * Other scientists/people review the experiment and the data or repeat the experiment to see if the hypothesis is reasonable.
Important features of the scientific process * Curiosity * Skepticism * Peer review * Reproducibility •Openness to new ideas
Scientists Use Reasoning, Imagination, and Creativity to Learn How Nature Works * Inductive reasoning: Involves using specific observations and measurements to arrive at a general conclusion or hypothesis * Example: After dropping multiple objects from different heights we can conclude that objects will drop to the ground when we let them go. * Deductive reasoning: Using logic to get to a certain conclusion. * Example * Generalization or premise: all birds have feathers * Eagles are birds * Deductive conclusion: Eagles have feathers
Scientific Theories and Laws Are the Most Important Results of Science * Difference between Scientific Theory and Hypothesis * If many observations and studies support a hypothesis then it becomes a theory. * Theories must be supported by a multitude of tests and evidence from multiple scientists * A hypothesis is a tentative explanation that still requires more evidence to support it. * Scientific law or law of nature: A well-tested and widely accepted description of what we find happening over and over against in the same way in nature. * Paradigm shift: When new ideas overturn old ideas or theories.
The Results of Science Can Be Tentative, Reliable, or Unreliable * A fundamental part of science is testing * Tentative science or frontier science: Ideas that haven’t been peer-reviewed or widely tested and aren’t reliable. * Reliable science: Ideas that have data to support them and are accepted by scientists. * Unreliable science: Ideas that have not been tested widely or by others. It can also be ideas that have been tested but proven wrong so they are discarded.
Environmental Science Has Some Limitations * Scientists can disprove things but cannot prove things with 100% certainty * There can be bias in the experiments/tests * Things cannot be 100% accurately measured statistically. There is more estimation present. * There are many variables in the environment which can make experimenting with each thing expensive * The scientific process is only for natural-world questions but not ethical or moral questions. * Scientists cannot prove or disprove anything absolutely * Scientists are not free of bias about their own hypotheses and results * Systems in the natural world involve a huge number of variables and complex interactions
Tentative science, frontier science * Not yet considered reliable by the scientific community
Reliable science * Widely accepted by experts
Unreliable science * Has not been through peer review or has been discredited

2.2 What is Matter?

Matter consists of Elements and Compounds * Matter: Anything that has mass and takes up space * Elements: Each one of which is a fundamental material with a distinct set of qualities that cannot be chemically broken down into smaller chemicals. * Compounds: Combinations of two or more different elements held together in fixed proportions
Atoms, Ions, and Molecules Are the Building Blocks of Matter * Atom: The most basic building block of matter * Atomic theory: The idea that all elements are made up of atoms * Atomic number: Equal to the number of protons in the nucleus of its atom. * Mass number: The total number of neutrons and protons in its nucleus * Subatomic Particles: * Subatomic particles * The nucleus of the atom * Protons have a positive charge * Neutrons have a negative charge * Negatively charged electrons orbit the nucleus * Nucleus: Contains one or more protons and, in most cases, one or more neutrons * Isotopes: Forms of an element having the same atomic number but different mass numbers * Ion: Second building block of matter. Atoms or groups of atoms with one or more net positive or negative electrical charges * Acidity: A chemical property that influences how an object dissolved in water will interact with and change its surroundings. * pH: Measure of acidity * Below 7: Acidic solution * Exactly 7: Neutral solution * Above 7: Base solution * Molecule: A combination of two or more atoms of the same or different element held together by a chemical bond. * Chemical formula * Show the number of each type of atom or ion in a compound. (ex. NO3) * Important Elements * Hydrogen: H * Carbon: C * Oxygen: O * Nitrogen: N * Phosphorus: P * Sulfur: S * Chlorine: Cl * Fluorine: F * Bromine: Br * Sodium: Na * Calcium: Ca * Lead: Pb * Mercury: Hg * Arsenic: As * Uranium: U * Important Ions * Hydrogen ion: H+ * Sodium ion: Na+ * Calcium ion: Ca2+ * Aluminum ion: Al3+ * Ammonium ion: NH4+ * Chloride ion: Cl- * Hydroxide ion: OH- * Nitrate ion: NO3- * Sulfate ion: SO4^2- * Phosphate ion: PO4^3- * Important Compounds * Sodium chloride: NaCl * Carbon monoxide: CO * Carbon dioxide: CO2 * Nitric oxide: NO * Nitrogen dioxide: NO2 * Nitrous oxide: N2O * Nitric acid: HNO3 * Methane: CH4 * Glucose: C6H12O6 * Water: H2O * Hydrogen sulfide: H2S * Sulfur dioxide: SO2 * Sulfuric acid: H2SO4 * Ammonia: NH3
Organic Compounds are the Chemicals of Life * Organic compounds: Contain at least 2 carbon atoms and combine with atoms of one or more elements. * Types * Hydrocarbons and chlorinated hydrocarbons * Simple carbohydrates * Macromolecules: complex organic molecules * Complex carbohydrates, proteins, nucleic acids, and lipids * Inorganic compounds: Any other compounds that do not classify under an organic compound are put under this classification. * Macromolecules: Larger and more complex organic compounds are composed of this. Essential for life. * Polymers: Created when multiple monomers come together through chemical bonds. * Monomers: Simple organic molecules * Complex carbohydrates: Such as cellulose and starch, consist of two or more monomers of simple sugars such as glucose. * Proteins: Created by monomers called amino acids * Nucleic acids: Formed by monomers called nucleotides (DNA/RNA) * Lipids: Include fats and waxes, essential for life.
Matter Comes to Life through Genes, Chromosomes, and Cells * Cells and molecules are the fundamental structural units of life * Genes: Sequences of nucleotides in DNA molecules. They contain genetic information that allows us to create specific proteins * Trait: Each code of genetic information creates this and it’s a characteristic that’s given to the offspring by the parent. * Chromosome: Thousands of genes make one of these. Genetic information in this makes you unique and different from other species. * Relationship between genetic material to cells * A human body contains trillions of cells, each with an identical set of genes. * Each cell except for red blood cells contains a nucleus * Each has an identical set of chromosomes that are in pairs * A pair of chromosomes have 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.
Matter Occurs in Various Physical Forms * Atoms, ions, and molecules have 3 physical states * Solid * Most compact and orderly arrangement * Liquid * Somewhere in between solids and gases * Gas * Has the least compact and orderly arrangement
Some Forms of Matter Are More Useful Than Others * Matter quality: The usefulness of a resource to us based on its availability and concentration * Concentration: Amount that is contained in a given area/volume * High-quality matter: High concentrations and is very available. High potential to be used as a resource

2.3 How can matter change?

Matter Undergoes Physical, Chemical, and Nuclear Changes * Physical changes: The arrangement of its atoms or ions does not change when change happens. * Chemical change/reaction: There is a change in the arrangement of atoms or ions within molecules of the substances involves. * Nuclear changes: Changes in the nuclei of its atoms. * Natural radioactive decay: Isotopes spontaneously emit fast-moving subatomic particles, high energy radiation such as gamma rays, or both. * Radioactive isotopes/radioisotopes: Unstable isotopes * Nuclear fission: When hit by neutrons, the heavy nuclei of some isotopes are broken up into lighter ones. Each process produces two or three neutrons as well as energy. * Nuclear fusion: Nuclear change in which two isotopes of light elements are forced together at high temperatures until they make a heavier nucleus.
We Cannot Create or Destroy Matter * Law of conservation of matter: No atoms are generated or destroyed during a physical or chemical change.

2.4 What is energy and how can it be changed?

Energy Comes in Many Forms * Energy: Is the capacity to transfer heat * Kinetic energy: Moving matter/energy * Heat: The total kinetic energy of all moving atoms, ions, or molecules within a given substance. * 3 methods of heat transportation * Radiation: The emission of electromagnetic energy * Conduction: The transfer of kinetic energy between substances in contact with one another. * Convection: The movement of heat within liquids and gases from warmer to cooler portions. * Electromagnetic radiation: Another form of kinetic energy. It travels in waves. * Radio waves, telewaves, etc. * Wavelength: Distance between successive peaks or troughs in the wave. * Potential energy: This is stored and potentially available for use.
Some Types of Energy Are More Useful Than Others * Energy quality: Measure of an energy source’s capacity to do useful work. * High-quality energy: Concentrated and has a high capacity to do useful work. * Low-quality energy: It disperses and has little capacity to do useful work.
Energy Changes Are Governed by Two Scientific Laws * Law of conservation of energy or The first law of thermodynamics: When energy is converted from one form to another in a physical or chemical change, no energy to created or destroyed * Energy consumption: Transferring energy across forms without causing any energy to be created or destroyed. * The second law of thermodynamics: We always end up with lower-quality or less useable energy than we did when energy transforms from one form to another. * Energy efficiency or energy productivity: This is a measurement of how much productive work is carried out by a specific energy input into a system.

2.5 What are systems and how do they respond to change?

Deforested areas turning to desert * Coral reefs dying * Glaciers melting * Sea levels rising
Systems Have Inputs, Flows, and Outputs * System: Set of components that function and interact in some regular way * Inputs: Come from the environment * Flows or throughputs: Matter and energy within the system of certain rates * Outputs: Goes to the environment
Systems Respond to Change through Feedback Loops * Feedback: Any process that increases (positive feedback) or decreases (negative feedback) a change to a system * Feedback loop: When a system's output of matter, energy, or information is sent back into it as an input, the system is changed. * Positive feedback loop: Causes a system to change further in the same direction * Negative or corrective feedback loop: Causes a system to change in the opposite direction from which is it moving
Time Delays Can Allow a System to Reach a Tipping Pointe * Time delays: Complex systems often show time delays between the input of a feedback stimulus and the response to it. * Threshold level or tipping point: Time delays can also allow an environmental problem to build slowly until it reaches a tipping point.
System Effects Can Be Amplified through Synergy * Synergistic interaction or synergy: This happens when two or more processes work together to produce an effect that is bigger than the sum of the effects of each process acting alone