2. Science is built up of facts, as a house is built of stones; but an accumulation of facts is no more a science than a heap of stones is a house. Henri Poincare

3. Chapter 2 Science, Matter, Energy, and Systems

4. Key Concepts
Scientists collect data, develop theories, models and laws
Matter is made up of atoms, elements and molecules
Law of conservation of matter
First law of thermodynamics
Second law of thermodynamics
Systems have inputs, outputs and feedback

5. Science: A Search for Order
Effort to discover how nature works
Uses observations, measurements, experiments
Assumes that natural events follow cause-and -effect

6. The Scientific Method Identify problem Literature search
Ask question to be investigated
Perform experiment
Analyze data (check for patterns)
Formulate hypothesis to explain data
Perform experiment to test hypothesis
Accept hypothesis/ Reject hypothesis
Scientific Theory
Revise hypothesis

7. Elements of the Experiment
Variables: factors that affect processes in the experiment
*independent variable- tested variable
** dependent variable- measured variable
Only I variable is tested at a time
Experimental group has independent variable
Control group lacks tested variable (provides basis for comparison)

8. Features of Scientific Processes
Curiosity
Creativity
Critical thinking
Skepticism
Reproducibility
Peer review

9. Goals of Science
Scientific theories: well-tested, widely accepted related hypotheses
*may be revised with new info
Scientific laws/law of nature: well-tested, widely accepted descriptions of what is found repeatedly in nature
*cannot be broken
Models: simulation of a natural system

10. Results of Science
Tentative/frontier science: results that are not yet reliable (new findings)
Reliable science: accepted by scientific consensus
Unreliable science: rejected by scientific consensus (usually because results were not reproducible)

11. Limits of Science
Scientists cannot prove or disprove anything absolutely
Scientists are not totally free of bias
Natural systems involve too many variables to control (important to environmental science)
Statistical sampling is often used to estimate measurements (think: probability)
Cannot be applied to ethical questions

12. Matter Anything with mass, volume Physical states: solid, liquid, gas
Exists as an element (fundamental) or in compounds (combinations of different elements)

13. Atoms/Elements Basic unit of matter
*atomic theory: atoms make up elements
Internal structures: neutrons (n), protons (p),
electrons (e)
Atomic number: equals number of protons
Mass number: total number of protons and neutrons
Isotopes: same atomic number, but different mass

14. Helium electron proton neutron Atomic Number: 2 Atomic Mass: 4 - - N +

15. Isotopes

16. Molecule/Compound Two or more different element chemical bound
*covalent bond: valence electrons are shared
** ionic bond: movement of electrons
between ions
Covalent bond
Ionic bond

17. Ions Atom/group of atoms with a positive or negative charge
(superscript indicates charge- NH₄⁺)
Important for measuring acidity:
* determines how materials dissolve
** measured by pH:
More H⁺ than OH¯
More OH¯ than H⁺

18. Compounds Organic: contain at least 2 carbons
Inorganic: all other compounds

19. Organic Compounds Hydrocarbons: C, H (methane-CH₄)
Chlorinated hydrocarbons: C, H, Cl (DDT)
Simple carbohydrates: C,H,O (glucose)
Macromolecules: complex carbohydrates, porteins, nucleic acids and lipids

20. Macromolecules Compound Composed of: Function Examples Carbohydrate
C,H,O
Releases energy for cells
Sugar
Starch
Cellulose

21. (made up of amino acids)
Macromolecules
Compound
Composed of:
Function
Examples
Protein
(made up of amino acids)
C,H,O,N
Building blocks of cell, enzymes
lactase

22. Macromolecules Compound Composed of: Function Examples Lipids
C,H,O
Stores and releases energy for cell
(more than carbs)
Fats, waxes, oils

23. Macromolecules Compound Composed of: Function Examples Nucleic Acids
C,H,O,N,P
Stores hereditary material
DNA, RNA

24. Living Matter Cell: basic functioning unit of life (cell theory)
Genes: sequences of nucleotides that code for specific traits
Chromosome: made up of thousands of genes

25. Matter Quality Measure of how useful matter is to humans;
based on availability, concentration
* high quality matter: high concentration,
great resource, usually found near Earth’s
surface
** low quality matter: low concentration,
resource, deep underground or dispersed

27. Types of Change in Matter
Physical change: no change in chemical
composition (ice melting)
Chemical change/reaction: change in chemical composition

28. Types of Change in Matter (cont’d)
Nuclear change: change in the nuclei of atoms
Radioactive decay: unstable isotope sheds
fast-moving particles
- half life: time needed for ½ of nuclei to decay
into a more stable form
Nuclear fission: nuclei of isotopes with large
mass split into lighter nuclei
Nuclear fusion: two isotopes of light
elements fuse to form a heavier nucleus

29. Nuclear Changes
Radioactive Half-Lives

30. Nuclear Changes
Fission
Fusion

31. Law of Conservation of Matter
No atoms are created or destroyed when matter undergoes physical or chemical changes
(This law means we really cannot “throw” away anything. Pollution changes form, but never goes away)

32. Energy Capacity to do work or to transfer heat
Kinetic energy: associated...
1. motion
2. heat (moving atoms; flow from cold to hot)
3. electromagnet radiation
a. travels in waves
b. wavelength reflects energy (shorter
waves = greater energy)

33. Energy (cont’d)
Electromagnetic Radiation

34. Energy (cont’d)
Potential energy: stored (potential for us)

35. Natural/Commercial Energy Sources
Sun is source for most energy on Earth
Solar energy produces wind, hydropower, biomass fuels
Fossil fuels (oil, coal, natural gas) produces commercial energy

36. Energy Quality High-quality energy: concentrated, high work capacity
ex.s- high temperatures, direct sunlight, burning coal
Low-quality energy: dispersed, low work capacity
ex.s- low temperatures, indirect sunlight, burning crop wastes

37. Energy Quality

38. Laws of Energy Transfer
First law of thermodynamics: no energy is created or destroyed when energy is converted from one form to another
Second law of thermodynamics: energy
conversions always result in a less useful form of energy due to loss in form of heat
(we can never reuse/recycle energy to do work)

39. Systems
Set of components that function and interact in a regular way. Made up of:
Inputs from the environment
Flows/throughputs of matter or energy within system
Outputs to the environment
ex.s- human body, an economy, a river

40. Outputs: Work/Products Waste
Systems
Inputs:
Energy
Matter Information
Throughputs
Outputs: Work/Products Waste
Heat

41. System Changes
Feedback: process that increases (positive) or decreases (negative) a change to a system
Feedback loop: output is fed back into a system as input; results in change to the system

42. Positive Feedback Loop
Causes system to increase change in same direction
Ex:
Decreasing Vegetation
Erosion
Nutrient Loss

43. Negative Feedback Loop
Causes a system to move in the opposite direction from which it is moving
ex:
Warm house causes thermostat to turn furnace off
House Cools
Temperature drop triggers thermostat to turn furnace on
House Warms

44. System Regulations
Time delay: time between the input of a feed- back stimulus and the system’s response to it
ex. Replanting a forest to slow erosion
Tipping point: point at which a system is changed irreversibly
ex. Erosion results in so much nutrient loss that land can no longer support trees

46. Synergy
Synergistic interaction (synergy): interaction of two or more processes to create a greater effect than each process separately
(ex. Nonsmoker exposed to asbestos is 5 х more likely to get cancer than a smoker; a smoker exposed to asbestos is 50 х more likely to get cancer than a nonsmoker)