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Science, Systems, Matter, and Energy
Chapter 3
Science as a process for understanding
Components and regulation of systems
Matter: forms, quality, and how it changes; laws of matter
Energy: forms, quality, and how it changes; laws of energy
Objectives
ScienceScientific Data
Hypothesis – based on observations
Scientific Theories - verified, widely accepted hypothesis
Scientific Laws - happens over and over in nature (Thermodynamics)
Ask a question
Do experimentsand collect data
Formulatehypothesis
to explain data
Do moreExperiments totest hypothesis
Revise hypothesisif necessary
Well-tested andaccepted
hypothesesbecome
scientific theories
Interpret data
Well-tested andaccepted patternsIn data becomescientific laws
Scientists Use ReasoningInductive
- specific observations to arrive at a general conclusion
Example: drop several objects and conclude that all objects fall to the earth’s surface when dropped
Deductive - generalizations to arrive at a specific
conclusion Example: all birds have feathers, therefore
eagles have feathers
Two Types of ScienceFrontier Science
- not widely tested and acceptedExample: herbal remedies
Consensus Science- widely accepted by expert scientists
Example: gravity, thermodynamics, etc.
SystemsSet of components that …
1. function and interact in a predictable manner.
2. can be isolated for observation.
Components of systems are …1. Inputs – what is put into the system.2. Flows – what is within the system.3. Stores – what is accumulating
within the system.4. Outputs – what flows out of the
system.
How are Systems Regulated?Positive Feedback
- Change in one direction causes further change in the same direction.
Example: money in the bank accumulating interest
Negative Feedback- Change leads to lessening of that change.Example: recycling aluminum cans
How do Time Delays affect Systems?
Can allow a problem to build up slowly until it reaches a threshold.
Can cause a fundamental shift in the system.
Examples:- leak from toxic waste dump- lung cancer 20 years after smoking
cessation
How can Synergy affect Systems?
Synergy1 + 1 = 3?- Combined affect is more than the
sum of their separate effects.
- Example: Moving a 300 lb. logPerson 1 = 100 lbs.Person 2 = 100 lbs.
Matter: Forms, Structure, and Quality■ Element:
building blocks of matter
■ Compound:two or more elements combined
■ Atom:smallest units of matter
■ Ion:charged atom
■ Molecule:two or more atoms combined
What’s in an Atom?Protons
+ positive charge Neutrons
no charge Electrons - negative
chargeAtomic Number
number of protons
Fig. 3-4 p. 48
Examples of Atoms
Chemical Bonds
Covalent – “sharing”
Chemical Bonds
Ionic - “transfer of electrons”
Hydrocarbons – natural gas (CH4) Chlorinated Hydrocarbons –
DDT (C14H9Cl5) Chlorofluorocarbons – aerosals
and AC Coolant Carbohydrates – glucose, sucrose,
fructose, galactose Proteins – amino acids with
carbon backbones
Organic Compounds
Solid
Liquid
Gas
Plasma
The Four States of Matter
Which State of Matter is the Most Abundant?
PlasmaPlasma- sun and stars- high energy mix of + and –
particles- formed when electrons are
taken from the nuclei of atoms (high energy process)
Matter Matter Quality - Measure of how useful a form of matter is to us as a resource, based on its availability and concentration.
High Quality Matter1. Fairly easy to extract and concentrated.2. Found near the Earth’s
surface.3. Great potential for use as a
resource.
Matter Continued Low Quality Matter
1. Dilute2. Deep underground or dispersed
in the ocean (difficult to extract).3. Little potential use as a
resource.
Material Efficiency- Amount of material needed to produce
each unit of goods or services.
Forms of Energy Kinetic - energy in motionExamples: Wind, Flowing Streams, Electricity
Potential - stored energyExamples: Unlit Stick of Dynamite, Rock in Hand
Convection Conduction Radiation
Heat from a stove burner causes atoms or molecules in the pan’s bottom to vibrate faster. The vibrating atoms or molecules then collide with nearby molecules, causing them to vibrate faster. Eventually, molecules or atoms in the pan’s handle are vibrating so fast it becomes too hot to touch.
As the water boils, heat from the hot stove burner and pan radiates into the surrounding air, even though air conducts very little heat.
Heating in the bottom of a pancauses the water to vaporizeinto bubbles. Because they are lighter than the surrounding water, they rise. Water then sinks from the top to replace the rising bubbles. This up and down movement (convection) eventually heats all of the water.
Transfer of Heat Energy
Energy Energy Quality - Energy source’s ability to do useful work.
High Quality Energy 1. Concentrated 2. Provides useful work Examples: Electricity, Concentrated Sunlight
Energy Continued
Low Quality Energy 1. Dispersed
2. Little useful work Example: Heat dispersed in the Atlantic Ocean.
Why is There No “Away”?
Law of Conservation of Matter
We cannot destroy atoms. We can only rearrange
them into different spatial patterns (physical) or into different combinations (chemical).
Everything we think we have “thrown away” is still here in one form or another.
Example DDT - banned, but still residues in imported coffee, tea, fruit, and other foods. - or as fallout from air masses moved long distances by wind.
Law of Conservation of Matter - means we will always face the problem of what to do with wastes and pollutants.
Pollution3 Factors that Determine the Severity of a
Pollutant’s Chemical Effects:1. Chemical Nature2. Concentration
- parts per million (ppm)3. Persistence
- measure of how long the pollutant stays in the air, water, soil, or body.
Classification of Pollutants:1.Degradable (reduced to acceptable levels)2.Slowly Degradable (decades or longer-DDT)3.Nondegradable (natural processes cannot break
down -lead, arsenic)
Nuclear Changes
Matter undergoes a nuclear change:
1. natural radioactive decay2. nuclear fission3. nuclear fusion
Natural Radioactive Decay A nuclear change in which unstable
isotopes spontaneously emit fast- moving particles (matter), high-energy radiation, or both at a fixed rate.
Unstable Isotopes are called “radioactive isotopes” - radioactive decay continues until isotope becomes stable.
Isotopes have a different number of neutrons but the same
number of protons.
Natural Radioactive Decay Continued
Radiation emitted by radioisotopes is damaging ionizing radiation.
Gamma Rays – a form of high-energy electromagnetic radiation emitted from radioisotopes. You do not want to be
exposed to these waves. Alpha/Beta Particles – high-speed
ionizing particles emitted from the nuclei of radioisotopes.
What is Half-Life?
The amount of time needed for one-half of the nuclei in a given quantity of a
radioisotope to decay and emit their radiation to form a different isotope.
Decay continues, often producing a series of different radioisotopes, until a stable, nonradioactive isotope is formed.
The half-life estimates how long a sample ofradioactive isotope must be stored
in a safe container before it decays to a safe level and can be released into the
environment.
Half-Life Continued A general rule is that such decay to a safe
level takes about 10 half-lives. Example: Plutonium-239 has a half-life
24,000 years. It is produced in nuclear reactors and used in nuclear weapon production. It must be stored safely for 240,000 years (10 x 24,000).
Plutonium-239 can cause lung cancer when its particles are inhaled in minute amounts.
Ionizing radiation exposure from alpha particles,beta particles, and gamma rays can damage cells by genetic damage (mutations of DNA) or somatic damage (tissue damage).
Nuclear Fission Neutrons can split apart the nuclei of certain isotopes with large mass numbers and release a large amount of energy.
1. Neutron hits the nucleus of an isotope.
2. Nucleus splits and releases 2 or 3 more neutrons and ENERGY.
3. Each of these neutrons can go on to cause additional fission. Multiple fissions create a chain reaction which releases an ENORMOUS AMOUNT OF ENERGY.
Examples of Nuclear Fission Atomic Bomb – An enormous amount of energy is released in a fraction of a second in an uncontrolled nuclear fission chain reaction. Nuclear Power Plant – The rate at which the nuclear fission chain reaction takes place is controlled. In conventional nuclear fission reactors, the splitting of uranium- 235 nuclei releases energy in form of heat, which produces high-pressure steam to spin turbines and thus generate electricity.
Nuclear Fusion Nuclear fusion is a nuclear change in
which extremely high temperatures force the nuclei of isotopes of some lightweight atoms to fuse together and form a heavier nucleus which in turn releases large amounts of energy.
Extremely high temperatures (at least 100 million oC) are needed to force the positively charged nuclei (protons strongly repel one another) to fuse.
Source of energy in sun and stars.
Sun-hydrogen isotopes fuse to make helium-energy and heat.
What are Nuclear Reactions used for?
Energy Production: nuclear power plants generate electricity for our homes.
Medical Technology: cancer treatment, X-rays.
Nuclear Weapons: atomic bomb, hydrogen bomb.
Nuclear Power Plant
Atomic Bomb
Laws of ThermodynamicsFIRST LAW OF
THERMODYNAMICS In all physical and chemical changes, energy is
neither created nor destroyed, but it may be converted from one form to another.
Energy input always equal energy output. You cannot get something for nothing in terms
of energy quantity.
SECOND 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, usually heat.
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