Living in the Environment – Ch.3
Science, Systems, Matter, Energy
3-1 The Nature of Science
Science is an attempt to discover order in the natural world and to use that knowledge to describe what
is likely to happen in nature. (See text for diagram) Scientists are involved in a never-ending cycle of
asking questions and trying to answer them in a logical and unbiased manner.
- Ask a question
- Do experiments and collect data > interpret data > Well-tested and accepted patters in data
become scientific laws
- Formulate hypothesis to explain data
- Do more experiments to test hypothesis
- Revise hypothesis if necessary
- Well-tested and accepted hypothesis become scientific theories
Variables or factors influence most parts of nature that scientists seek to understand.
Controlled experiment is isolating and studying the effect of a single variable.
- Experimental group: the chosen variable in changed in a known way
- Control group: the chosen variable in not changed
Inductive reasoning: using specific observations and measurements to arrive at a general
conclusion/hypothesis (bottom up = specific to general)
ex. Items dropped at various heights, inductive reasoning is that all objects fall to the Earth’s surface
Deductive reasoning: using logic to arrive at a specific conclusion based on a generalization or premise.
(top-down = general to specific)
ex. Generalization or premise: All birds have feathers.
Example: Eagles are birds.
Deductive conclusion: All eagles have feathers.
Syllogism is a series of logically connected statements.
Scientists can disprove things, and can establish that a theory etc. has a very high probability of certainty
of being true.
Frontier science: results that is controversial because they have not been widely tested/accepted.
Sound science: consists of data/theories/laws that are accepted by scientists who are experts in the field
Junk science: results/hypothesis that have been presented as sound science but not having undergone
the peer review process. 3-2 Models and Behaviour of Systems
System: a set of components that function and interact in some regular and theoretically
Inputs, from environment (energy, info, matter) > Throughputs, rates of flow (Human body) > Outputs,
to environment (heat, ideas and actions, waste and pollution)
Feedback loop occurs when output of matter/energy/information is fed back into the system as an
input, leads to changes in that system.
- Positive feedback loop: causes system to change further in the same direction
ex. Depositing money in bank at compound interest and leaving it there, interest increases
balance, positive feedback loop leads to more interest and higher balance.
- Negative feedback loop: causes system to change in opposite direction.
ex. Recycling aluminum cans, melting and feeding back into economic system to make new
aluminum products, negative feedback loop reduces need to find/extract/process virgin
aluminum ore, reduces flow of waste matter.
Any action in a complex system has multiple and often predictable results, try to anticipate and plan for
unintended results and surprises.
Matter: anything that has mass and takes up space.
Elements: the building blocks of matter that makes up every material substance.
Compounds: two or more different elements held together in fixed proportions by attractive forces
called chemical bonds.
Natural capital degradation: human activities > intentions > unintended results
Atom: smallest unit of matter that exhibits the characteristics of an element.
Ion: an electrically charged atom, or combination of atoms.
Molecule: a combination of two or more atoms of the same or different elements held together by
What atoms are made of…
Protons: positively charged
Electrons: negatively charged
Nucleus: extremely small center
Protons are inside nucleus, electrons are outside nucleus. Each has a certain number.
Atomic number: each element has its own, equal to number of protons in the nucleus
Mass number: total number of protons and neutrons in nucleus.
ex. Protons+Neutrons=Mass Number
Isotopes: Elements with the same atomic number but with different mass number. Atoms of some elements can lose or gain one or more electrons to form ions with positive or negative
electrical charges. Thus, ions form when an atom of an element loses or gains one or more electrons.
Giving, receiving, and sharing electrons hold the atoms and ions in compounds together. Some
compounds are made up of oppositely charged ions and others are made up of molecules.
Chemical formula: is what chemists use to show the number of atoms or ions of each type in a
Ionic compound: made up of oppositely charged ions.
ex. Table salt (NaCl)
Molecular compound: made up of molecules of uncharged atoms.
ex. Water (H2O)
pH value: is a measure of the concentration of hydrogen ions (H+) in a water solution.
(>7= acidic, 7=neutral, <7=basic)
Organic compounds contain carbon atoms combined with one another and with various other atoms
such as hydrogen, nitrogen, or chlorine.
ex. Table sugar, vitamins, plastics, most chemicals in the body.