Science, Systems, Matter and Energy
Scientific method
Observation
Problem
Possible solution-hypothesis
Test Hypothesis
Analyze data
Conclusion-support or refute hypothesis.
New hypothesis are developed if necessary.
[Repeated observations, averaging data, using accepted standards avoiding bias]
Scientific laws—events that happen over and over again.
Scientific theories—extensively tested hypothesis that can predict future observations.
Paradigm shift When new facts disprove old explanations/theories.
Continental drift
Models
Simulations that describe the different parts of a system and how they interact.
Positive feedback loop causes a system to further change in the same direction
Compound interest in a bank—interest on money--interest on money + interest
Melting of ice caps to water—absorbs more light—more heat—more melt
Negative feedback loop causes a system to to change in the opposite direction
Thermostat turns on furnace—home heats-turn off the heat
Recycling aluminum reduces need for mining for new products
Feedback loops [positive and negative ]
Time delays—sometimes an event does not have an immediate response
Smoking and lung cancer
Synergy—when two actions amplify the effect of each alone. On Easter Island the people used tree
and soil resources faster than they regenerated. [E.G. “Tragedy of the Commons”] Without forests to
absorb and slowly release water springs and streams dried up, soil was lost. Crops lost, all animal life
eaten and warfare broke out between clans.
Elements
Atoms,
Subatomic particles: Proton, neutron, in nucleus, electrons in energy levels surrounding the nucleus.
Filled shells make an atom more stable.
2 electrons fill the first energy level 8 the second and 8 the third.
Isotopes: different forms of the same element. U 235 and U237 are forms of uranium
C12, C13, C14 different forms of carbon, C14 is instable-radioactive.
Covalent bonding-atoms share electrons in order to fill the outer shell.
Ionic bonding-atoms transfer electrons in order to fill the outer shell because sharing is not possible.
Transferring electrons creates charged atoms [ions] that attract by pos. to neg. charges.
Hydrogen bonding-when electrons are not equally shared the H show a slight positive charge. This
positive hydrogen is attracted to any negative molecule.
Water is a polar molecule, oxygen pulls harder than the Hydrogen so the oxygen end is negative and
the hydrogen ends are positive.
pH water will separate into H+ and OH- ions
this means the amount of H+ and OH- are equal called neutral pH7
if H+ is added from the environment H+ > the OH- called an acid pH 6 –
if OH- is added from the environment H+ < the OH- called a base pH 8 +
pH important because it can dissolve metals and once dissolved they can be absorbed by living
organisms with negative effects. pH also determines the shape of proteins in living organisms.
Organic molecules
Contain carbon.
Cell is the basic unit of life.
Prokaryotes, simple ancient, many different types of chemistry
Eukaryotes, have nucleus and organelles, arose well after the prokaryotes.
Macromolecules [large], the molecules that living organisms are made from.
Carbohydrates, sugar, starch, cellulose, glycogen
Lipids, fat, phospholipids, streoids
Protein-cell structures and enzymes [proteins that cause chemical reactions]
Nucleic Acids. DND, RNA
States of matter
Solid, liquid, gas, plasma
Quality matter is concentrated [solid vs. gas, gas vs. exhaust, salt vs. salt water]
Physical change. Ice to water…still water
Chemical change. Water and carbon dioxide becomes sugar and oxygen.
Conservation of matter, no atoms are created or destroyed.
Types of pollutants
Factors determining harmful effects:
Chemical nature
Concentration e.g. ppm parts per million
Persistence how long the pollutant stays in the environment
Degradable-breaks down by natural processes
Biodegradable-organisms break down the pollutant.
Slowly degradable takes decades or longer to degrade DDT, plastics
Nondegradable chemicals that natural processes cannot break down. Toxic elements like mercury,
arsenic.
Nuclear changes—can release energy
Radioactive fission, some element have unstable forms-radioactive isotopes. Nuclear change is
where chunks of the nucleus split off and leave the nucleus. alpha beta and gamma particles can leave
the nucleus.
These particles can damage living organisms.
Nuclear fusion—joining 2 or more nuclei into a single new nucleus. The sun is joining 4 hydrogen
into He with a slight loss in mass. The mass was change into the energy given off by the sun.
Energy the capacity to do work and transfer heat.
Potential-stored. Position-a rock that could fall. Shape in the bonds of sugar and gasoline. Water
behind a dam.
Kinetic energy-the energy in an object because of its speed or velocity. Wind, electricity, flowing
water, [Electromagnetic radiation-different forms of light. X rays, heat, U.V., etc.]
Quality
High quality, energy is concentrated and can do work
Low quality energy is dispersed with little ability to do work.
First law of thermodynamics-in all physical changes energy is neither created not destroyed but it
can be converted to other forms
Second law of thermodynamics when energy changes from one form to another some of the useful
energy is degraded to a lower more dispersed less useful energy.
Systems are highly structured, regular and predictable. Ex. your I phone an automotive plant or a
living cell.
Systems have input, throughput or flow and output.
High throughput = high waste. [industrial societies try to boost their economies by one way flow of
energy and materials] Matter recycling and reuse-more have low-throughput [low waste] economies
and are more sustainable.
Environmental threshold. A forest or field can be harvested for years and it still grows crops.
There is a level [tipping point] at which an effect, overharvesting causes permanent change. Over
harvest a forest, cannot recover—becomes a desert. Ex. People destroyed the environment of Easter
Island.