Science
Attempt to discover order in the natural world and to use that knowledge to make predictions about what is likely to happen in nature
Scientific theory
Widely tested and accepted hypothesis
Scientific / Natural law
What we find happening over and over again in nature
Peer review
(1) publish details of methods, results of experiments and models, reasoning behind hypotheses; (2) other scientists in same field examine and criticize
variables
The changing parts of the experiment
Controlled experiment
Isolate and study one variable at a time
Experimental group
chosen variable is changed in a known way
Control group
no treatment group
Constants
parts of experiment that Stay the Same
Inductive reasoning
specific observations and measurements arrive at a general conclusion or hypothesis
bottom-up reasoning going from
specific to general
Deductive reasoning
logic to arrive at a specific conclusion
top-down approach that goes from
general to specific
Frontier science
has not been widely tested (starting point of peer-review)
Sound science / Consensus science
consists of data, theories and laws that are widely accepted by experts
Junk science
is presented as sound science without going through the rigors of peer-review
Positive feedback loop
System changes further in the same direction
Example: loss of ice caps and global warming
Negative feedback loop
System changes in opposite direction; corrective
Example: aluminum recycling results in less aluminum ore needing to be mined from earth's crust
Synergy
Occurs when two or more processes interact so that the combined effect is greater than the sum of their separate effects
Example: smoking cigarettes and asbestos exposure: fifty times more likely to develop lung cancer
Matter
anything that has mass and takes up space; ex: solids, liquids, gases
Elements
building blocks of matter
Compounds
2 or more different elements held together
Atom
smallest unit of matter that exhibits characteristics of a specific element
Proton
found in nucleus of atom - positive charge
Neutron
found in nucleus of atom - no charge
Electron
floating" around nucleus of atom - negative charge
Nuclues
center of an atom made of protons and neutrons
Atomic number
number of protons in an atom
Mass number
number of protons and neutrons in an atom
Isotope
element with same atomic number (same protons) and different atomic mass due to different number of neutrons
Ion
atom or groups of atoms with net positive or net negative charge
pH
acidity of a solution; hydrogen ion concentration in 1 liter of water; "potential of hydrogen
neutral solution
pH of 7; ex: water
acidic solution
pH less than 7 and possibly as low as 0; ex: lemon juice, vinegar
basic solution
pH more than 7 and possibly as high as 14; ex: soaps, detergents, baking soda
Molecule
Two or more atoms of the same or different elements
Building blocks of compounds
Examples:
C6H12O6
O2
Chemical formula
shorthand ways to show the atoms and ions in a chemical compound.
Organic compound
has carbon and hydrogen; ex: macromolecules, biomass
Inorganic compound
may have carbon or hydrogen or neither; ex: water, minerals, salt, iron
Cells
basic structural and functional units of all forms of life
Macromolecules
organic and necessary for life; ex: carbohydrates, lipids, proteins, nucleic acids
Genes
segment of DNA that codes for a trait
Chromosomes
all the DNA of a cell condensed and found in the nucleus of eukaryotic cells; ex: humans have 46 of them in their body cells and only 23 of them in their sex cells
High-quality matter
is concentrated and easily extracted; ex: coal, gasoline
Low-quality matter
is more widely dispersed and more difficult to extract; ex: exhaust from automobile, air pollution and emissions from a power plant
Physical change
maintains original chemical composition; ex: breaking a piece of ice into smaller pieces of ice
Chemical change / chemical reation
chemical reaction which changes the arrangement of the elements or compounds involved; coal is burned and released into the air as sulfur dioxide and carbon dioxide
Law of conservation of matter
When a physical or chemical change occurs, no atoms are created or destroyed
Persistence
measure of how long it stays in the air, water, soil, or body
Degradable pollutants
broken down completely or reduced to acceptable levels
Biodegradable pollutants
living organisms (usually bacteria) break down matter
Slowly degradable pollutants
takes decades or longer to degrade; ex: DDT
Nondegradable pollutants
cannot be broken down; ex: lead, mercury, arsenic
Natural radioactive decay
unstable isotopes (radioactive isotopes or radioisotopes) spontaneously decay at a constant rate and give off energy
Radioactive isotopes / radioisotopes
unstable isotopes that result from natural radioactive decay
Half-life
time needed for one-half of the nuclei to decay to form a different isotope
Nuclear fission
splitting of atoms; ex: process used at nuclear power plant
Nuclear fusion
atoms being joined together; ex: process used on sun
Kinetic energy
energy in motion
Potential energy
energy at rest
Heat
flows from hotter object to cooler object
High-quality energy
concentrated; can perform much useful work
Low-quality energy
dispersed and has little ability to do useful work
Law of conservation of energy
also 1st law of thermodynamics; energy is not created or destroyed, just changes forms
Second law of thermodynamics
energy quality always decreases; entropy increases