Transcript Ch. 2

Science. Models, systems
“Scientific knowledge is a body
of statements of varying
degrees of certainty – some
most unsure, some nearly sure,
and none absolutely certain” –
Richard Feynman
Science and Technology
Science – knowledge of
how the world works
Technology – creation of
new processes intended to
improve the quality of life
Scientific method
HYPOTHESIS – proposed to
explain observed patterns
Critical experiments
Analysis and conclusions
Scientific law and Theory
Law – certain phenomena
always act in a predictable
manner
Theory – rational
explanation for numerous
observations of a certain
phenomena – global
warming due to greenhouse
effect
Accuracy Vs Precision
Accuracy – measurement agrees
with the accepted correct value
Precision – measure of
reproducibility
Types of reasoning
Inductive - using
observations and facts to
arrive at generalizations
Deductive - using logic to
arrive at a specific
conclusion
Feedback loop
Change in one part of a
system influences another
part of the system
Positive feedback loop
Exponential growth of
population – more individuals
lead to increased number of
births
Negative feedback loop
Temperature regulation in humans –
increased temperature leads to
decrease in temperature by sweating
Important Terms
Inputs - matter, energy,
information
Throughput - flow of input
Output - matter, energy,
information flowing out
Matter and Energy
Resources
Nature’s Building Blocks
anything that has mass and
takes up space
Forms of matter
elements – single type of atoms
110 elements – 92 natural +18
synthesized
compounds - 2 or more elements,
held together by chemical bonds
Building Blocks
atoms - smallest units of matter-
protons,neutrons,electrons
ion - electrically charged atoms
molecules - combinations of
atoms of the same or different
elements
Definitions
Atomic Number - number of protons
Isotopes - same atomic number,
different mass number
Ions - atoms can gain or lose one or
more electrons
Mass Number - protons + neutrons
Isotope
Elements
with same
atomic
number but
a different
mass
number
Some Important elements- composition
by weight – only 8 elements make up
98.5% of the Earth’s crust
Organic Compounds
with carbon
sugar, vitamins, plastics, aspirin
Environmental Organic
Compounds
Hydrocarbons = methane gas
Chlorinated hydrocarbons =.
DDT, PCB
Chlorofluorocarbons (CFC)Freon 12
Polymers
larger and more complex
organic compounds made up of
monomers
complex carbohydrates
proteins - 20 amino acids
nucleic acids - nucleotides
Inorganic compounds
no carbon,not originating from a
living source
Earth’s crust – minerals,water
water, nitrous oxide, nitric oxide,
carbon monoxide, carbon dioxide,
sodium chloride, ammonia
Matter quality
Measure of how useful a matter
is for humans based on
availability and concentration
Energy
capacity to do work and transfer
heat
Kinetic Energy -energy in action
electromagnetic radiation, heat,
temperature
Potential energy - stored energy
that is potentially available
Electromagnetic radiation
different wave lengths shorter –
high energy, disrupts cells with
long term exposure
Energy sources
97% solar
without it earth’s temperature 240 C
1% - non commercial(wood,
dung, crops) + commercial (
burning mineral resources)
Energy quality
Measure of
how useful an
energy source
is in terms of
concentration
and ability to
perform useful
work
Law of Conservation of Matter
elements and compounds
changed from one form to
another, can never be
destroyed
no “away” in “throw away”
Nuclear Changes
nuclei of certain isotopes spontaneously
change (radioisotopes) or made to change
into one or more different isotopes
Alpha particles – fast moving (2
protons+2neutrons); Beta particles – high
speed electrons ; Gamma particles - high
energy electromagnetic radiation
radioactive decay, nuclear fission,
nuclear fusion
Use….radioisotopes
Estimate age of rocks and fossils
Tracers in pollution detection and
medicine
Genetic control of insects
Half - Life
time needed for one-half of the nuclei
in a radioisotope to decay and emit
their radiation.
Goes through 10 half –lives before it
becomes a non-radioactive form
certain isotopes
(uranium 235)
split apart into
lighter nuclei
when struck by
neutrons
chain reaction
releases energy
needs critical
mass of
fissionable nuclei
Nuclear Fission
Nuclear fusion
two isotopes (hydrogen) forced
together at extremely high
temperatures (100 million C)
uncontrolled nuclear fusion
thermonuclear weapons
1st Law of Energy or 1st Law of
Thermodynamics
in all physical and chemical
changes energy is neither
created or destroyed
energy input always equal to
energy output
2nd Law of Energy or 2nd Law of
Thermodynamics
when energy is changed from
one form to another some of
the useful energy is always
degraded to lower quality, more
dispersed, less useful
energy(heat)
Implications for the environment –
High waste society
Implications for the environment
– Low waste society