Chapter 2: Science, Matter, Energy, and Systems

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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

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