Ch. 4 Interrelated scientific
principles
Matter, energy, and environment
Nature of science
Science is viewed differently:
Some see it as powerful and are threatened by it.
Some see it as powerful, and it can help them.
Some see it as powerful but limited by the government.
Science is
→ a process used to solve problems or develop an understanding of nature
involving testing possible answers.
→ how knowledge is acquired.
Basic Assumptions
→ make presumptions using scientific method
→ everything has a cause and effect
→ distinguish between correlation and cause and effect
→ systemic info search
→ Constant reevaluation, criticism, and modification
Elements of the scientific method
1. Careful observation
2. Ask questions about observed events.
3. Construct a hypothesis and test it.
4. Accepting new ideas and change
5. Accepting criticism and rejection
6. Theory and laws established.
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Hypothesis: testable statement providing a possible answer to a question.
→ logical
→ account for all relevant information currently available
→ allow prediction of future events
→ testable
The simplest hypothesis with the fewest assumptions is the best.
Controlled experiments are needed to support or disprove
Reproducibility is important in the scientific method to prove and provide more
evidence.
Constructive criticism from other scientists in a communication process to make
suggestions, criticize, or agree.
Then, it can be established as a:
Theory: widely accepted, plausible generalization that explains why things
happen.
Scientific law: the uniform or constant fact of nature describing what happens in
nature.
Matter
→ Anything that occupies space and its components
Matter is made of substance/s
If it can be separated physically, it is a mixture of substances.
Substances are either:
Compounds: can be separated chemically - multiple elements.
Elements: cannot be separated chemically
→ in the periodic table
Ch. 4 Interrelated scientific principles
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Structure of matter:
Kinetic molecular theory describes the structure and sctivity of matter.
It states that all matter is made out of atoms in constant motion.
Atoms are made of protons (posisitve charge), neutrons (neutral), and electrons
(negative charge)
Differs based on elements.
Isotopes: Atoms of the same element that have the same number of protons and
electrons but can differ in no. of neutrons
Hydrogen only element that can exist with 0 neutrons.
Molecules: atoms binded together into stable units - bringing more than one atom
together
Ions: electrically charged parrticles
→ atoms that lose electrons: posiitively charged
→ atoms that gain electrons: negatively charges
Compounds: 2 or more atoms or ions binded together - bringing two or more
different atoms together
Mixture: variable combinations of atoms, ions, or molecules
All compounds are molecules but not all molecules are compounds.
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Acids, bases, and pH
If pH is less than 7 it is an acid and more than 7 is a base.
Methods to see if something is a base or acid:
Litmus paper:
qualitative method
Acid turns paper red
Base turns paper blue
PH meter: measures levels of H+ and OHCalculation:
1. PH: -log [H+]
2. [H+]: antilog(-pH)
Shift, log, -, ph value
3. [H+] x [OH-] = Kw = water constant
Water constant = 1x10^-14 at 25° Celsius
=
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Inorganic and organic matter
Organic matter:
results from living in biological origin
Decay product of living organisms
Consists of organic compounds
Inorganic matter
non biological origin
Rocks, minerals, water, air
Chemical reactions
→ when bonds are formed or broken
results form interaction between atoms
Exothermic: heat is released to the surrounding
Endothermic: heat is absorbed from the surrounding
Activation energy: amount if energy required to start a reaction
Catalyst: substance that alters rate of reaction
Living organisms contain enzymes that act as catalysts and reduce the needed
activation energy.
Energy principles
Energy is neither created nor destroyed, only transferred between forms
When converting energy some useful energy is lost
work is done when an object is moved over a distance
→ kinetic energy: contained by moving objects
→ potential energy: energy due to relative position (based on elevation)
Sensible heat transfer: when heat energy flows from a warmwe object to a cooler
object.
→ temp of cooler matter increases and temp of warmer matter decreases.
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Latent heat transfer: when heat energy is used to change the state of matter but
the temperature of matter does not change.
Entropy: energy used that cannot be used to do useful work.
High quality energy can be used to perform useful work (electricity)
Low quality energy cannot be used to perform useful work (heat in the ocean)
Ch. 4 Interrelated scientific principles
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