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.