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