Chapter 2: Science, Matter, Energy, and

Systems

Is an endeavor to discover how nature works and to use that knowledge to make predictions about what is likely to happen in nature.

Science assumes that events in the natural world follow orderly patterns and that, through observation, measurements, experimentation and modeling, these patterns can be understood.

Curiosity is what motivates scientists.

What is science?

Identify a problem Find out what is known about the problem Ask a question to be investigated Collect data to answer the question Propose an hypothesis to explain data Make testable predictions Test the predictions with further

experiments, models or observations Accept or reject the hypothesis

Scientific Method (not always in the order listed)

A scientific theory is a verified, believable, widely accepted scientific hypothesis.

Scientific Theory

Curiosity, skepticism, peer review, reproductivity and openness to new ideas.

Features of the scientific process

Scientists use deductive and inductive reasoning and critical thinking skills but also use intuition, imagination, and creativity.

a. Inductive reasoning uses specific observations and measurements to arrive at a general conclusion.

b. Deductive reasoning uses logic to arrive at a specific conclusion based on a generalization.

A scientific theory has been tested widely, is supported by extensive evidence and is accepted by most scientists in a particular field or related fields of study.

A scientific law or law of nature is a well-tested and widely accepted description of what we find happening over and over again.

Theory/Law

Paradigm shifts occur when new discoveries overthrow well-accepted scientific theory.

Paradigm Shifts

is scientific results that have not been confirmed.

Some of these results will be validated and classified as reliable and some as unreliable

Tentative Science or Frontier Science

Consists of data, hypothesis, theories, and laws that are widely accepted by scientists who are considered experts in the field under study.

Reliable Science

Scientific hypothesis and results that are presented as reliable without having undergone the rigors of peer review or that have been discarded as a result of peer review.

Unreliable Science

a. Scientists can disprove things, but not prove anything absolutely.

b. Scientists are sometimes biased. However bias can be minimized.

c. Environmental scientists often rely on estimates.

d. Environmental phenomena often involve a multitude of interacting variables.

Environmental science has limitations

Matter consists of elements and compounds, which are in turn made up of atoms, ions, or molecules.

Matter is anything that has mass and takes up space.

What is matter?

Matter is made up of elements, each of which is a fundamental substance that has a unique set of properties and cannot be broken into simpler substances by chemical means

Compounds are combinations of two or more different elements held together in fixed proportions.

Elements/Compounds

1. An atom is the smallest unit of matter that exhibits the characteristics of an element.

2. An ion is an electrically charged atom or combinations of atoms.

3. A molecule is a combination of two or more atoms of elements held together by chemical bonds.

Atoms, Ions and Molecules

Types of subatomic particles:◦ Protons: Positively charged◦ Neutrons: No electrical charge◦ Electrons: Negatively charged

Each atom consists of :1. Nucleus2. Electron probability cloud

Atoms

Atomic number: number of protons Mass number: number of protons + number

of neutrons Isotopes: are various forms of an element

that have the same atomic number, but different mass number.

An ion is an electrically charged atom or combinations of atoms.

It is form when an atom gains or losses one or more electrons.

Ionic compounds are ions containing atoms of more than one element.

Nitrate ion is a nutrient essential for plant growth.

Ions are also important for measuring a substance´s acidity.

Ions

A molecule is a combination of two or more atoms of the same or different elements held together by chemical bonds.

Molecules

According to the usefulness of matter as a resource, it is classified as having high or low quality.

1. High-quality matter is concentrated with great potential for usefulness and is usually found near the earth’s surface.

2. Low-quality matter is dilute and found deep underground and/or dispersed in air or water.

 

Classification of matter

When matter has a physical change, its chemical composition is not changed; the molecules are organized in different patterns.

In a chemical change, the chemical composition of the elements/compounds change.

The Law of Conservation of Matter states that no atoms are created/destroyed during a physical or chemical change.

How can matter change?

B.

Radioactive decay

Nuclear fission

Nuclear fusion.

Nuclear Change in matter

Radioactive isotopes emit high-energy radiation at a fixed rate until the original unstable isotope is changed into a stable isotope.

Nuclei of certain isotopes with large mass numbers (uranium-235) are split apart into lighter nuclei. When struck by neutrons. This is nuclear fission.

Nuclear fusion occurs at extremely high temperatures and involves the fusion of two isotopes of light elements (H).

Is the capacity to do work or transfer heat.

Work is done when something is moved.

Work = Force x distance

Energy

Moving energy (kinetic energy)

Stored energy (potential energy)

Types of energy

Another form of kinetic energy Is the total kinetic energy of all moving

atoms, ions, or molecules within a given substance.

Heat can be transferred by different methods:

Radiation (electromagnetic energy) Conduction Convection

Heat

Energy travels in form of a wave. There are different types:

Short wavelengths: such a gamma rays, X rays, and UV (have a higher energy content)

Long wavelengths: such a visible light and IR radiation (less energy content)

Visible light makes up most of the spectrum of electromagnetic radiation emitted by the sun

Electromagnetic Radiation

Is a measure of an energy source’s capacity to do useful work.

High-quality energy is concentrated and has a high capacity to do useful work. Ex. Very high temperature heat, nuclear fission, gasoline, coal,…

Low-quality energy is dispersed and has little capacity to do useful work. Ex. Heat in the ocean

Energy quality

Also known as law of conservation of energy.

When energy is converted from one form to another in a physical or chemical change, no energy is created or destroyed.

First Law of Thermodynamics

Converting energy from one form to another with no energy being destroyed or created in the process.

What is changing is the energy quality (the amount of energy available that can perform useful work)

Energy consumption

When energy changes from one form to another, we always end up with lower-quality or less usable energy than we started with.

Usually this lower-quality energy takes the form of heat given off at a low temperature to the environment.

Second Law of Thermodynamics

Is a measure of how much useful work is accomplished by a particular input of energy into a system.

Scientists estimate that only 16% of the energy used in the US ends up performing useful work.

Energy Efficiency or Energy Productivity

Is a set of components that function and interact in some regular way. Ex. The human body, a river, the earth,…

Most systems have the following key components:◦ Inputs from the environment, ◦ flows or throughputs of matter and energy within

the system at certain rates.◦ Outputs to the environment

Systems

Most systems are affected one way or another by feedback, any process that increases (positive feedback) or decreases (negative feedback) a change to a system.

Feedback loop occurs when an output of matter, energy or information is fed back into the system as an input and leads to changes in that system.

Feedback

Positive Feedback Loop:Causes a system to change further in the same direction.

Negative or corrective feedback loop:Causes a system to change in the opposite direction from which is it moving

Feedback Loops

Complex systems often show time delays between the input of a feedback stimulus and the response to it.

Time delays can also allow an environmental problem to build slowly until it reaches a tipping point.

Tipping point: Threshold level at which an environmental problem causes a fundamental and irreversible shift in the behavior of a system.

Time Delays

Population growth

Leaks from toxic waste dumps

Global climate change

Degradation of forests

Tipping Points

A synergistic interaction, or synergy, occurs when two or more processes interact so that the combined effect is greater than the sum o their separate effects.

The combine or synergistic efforts of people working together can be more effective than the efforts of each person acting alone.

Synergy

Most of the environmental problems we face today are unintended results of activities designed to increase the quality of human life.

One factor that can lead to an environmental surprise is a discontinuity or abrupt change in a previously stable system when some environmental threshold or tipping point is crossed.

Human activities can have unintended harmful results