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Chapter 2
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Matter – mass + space
Atoms – elements; periodic table; symbols
o Atomic number, mass number, isotope
o Radioactivity
• Radioactive decay, half-life
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Compounds – formulas
o Covalent bonds – molecules (very strong)
o Ionic bonds – ions (slightly less strong)
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Additional types of bonds
o Hydrogen bonds – polarity (fairly weak)
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Strong covalent bonds hold oxygen and hydrogen together
Oxygen is much more electronegative than hydrogen  it is an
electron ‘hog’  the electrons spend more time around it than
hydrogen  water is a polar molecule
The slight – charge on the oxygen side of the molecule is
attracted to the slight + charge on the hydrogen side of another
molecule (hydrogen bonding)
This polarity and hydrogen bonding of water causes all its other
properties:
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o
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o
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Surface tension
Capillary action
Specific heat
Density of ice
Solubility
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Acids
o Excess H+ ions in solution
o NNO3 (nitric acid) and H2SO4 (sulfuric acid)
o pH < 7
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Bases
o Excess OH- ions in solution
o NaOH (sodium hydroxide) and Ca(OH)2 (calcium hydroxide)
o pH > 7
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The law of conservation of matter
o It’s a LAW! Chemical reactions must obey!
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How does this impact the environment?
o There is no ‘away’…
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Compounds
o Inorganic – no carbon or no carbon bound to hydrogen
o Organic – have carbon-carbon and carbon-hydrogen bonds
o Four important ones:
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Carbohydrates
Proteins
Lipids
Nucleic acids (DNA & RNA)
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Energy - the ability to do work; power – the rate of work
Forms of energy:
o Kinetic – energy of motion
o Potential – stored energy
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Temperature
o Kinetic energy of the molecules within a substance
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Energy has laws too!
First law of thermodynamics
o Not created or destroyed, just changed
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Second law of thermodynamics
o Changes in energy result in a decrease in usable energy and an
increase in entropy
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Open system: exchanges of matter or energy
o Example – a lake: water flows in as well as out
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Closed system: no exchanges of matter or energy
o Example – not as common; some underground cave systems
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Which is Earth with respect to matter? How about energy?
Steady state systems
o Input = output  system is not changing over time
o Most natural systems are in a steady state due to feedback
• Negative feedback loop – system returns to original state by decreasing
its rate of change (resists)
• Positive feedback loop – system accelerates by increasing its rate of
change (amplifies)