1. Environmental Systems
Chapter 2

2. Chemistry quick review
Matter – mass + space
Atoms – elements; periodic table; symbols
Atomic number, mass number, isotope
Radioactivity
Radioactive decay, half-life
Compounds – formulas
Covalent bonds – molecules (very strong)
Ionic bonds – ions (slightly less strong)
Additional types of bonds
Hydrogen bonds – polarity (fairly weak)

3. Water 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:
Surface tension
Capillary action
Specific heat
Density of ice
Solubility

4. Important solutions Excess H+ ions in solution
Acids
Excess H+ ions in solution
HNO3 (nitric acid) and H2SO4 (sulfuric acid)
pH < 7
Bases
Excess OH- ions in solution
NaOH (sodium hydroxide) and Ca(OH)2 (calcium hydroxide)
pH > 7

5. Matter The law of conservation of matter
It’s a LAW! Chemical reactions must obey!
How does this impact the environment?
There is no ‘away’…
Compounds
Inorganic – no carbon or no carbon bound to hydrogen
Organic – have carbon-carbon and carbon-hydrogen bonds
Four important ones:
Carbohydrates
Proteins
Lipids
Nucleic acids (DNA & RNA)

6. Energy Energy - the ability to do work; power – the rate of work
Forms of energy:
Kinetic – energy of motion
Potential – stored energy
Temperature
Kinetic energy of the molecules within a substance
Energy has laws too!
First law of thermodynamics
Not created or destroyed, just changed
Second law of thermodynamics
Changes in energy result in a decrease in usable energy and an increase in entropy

7. Systems analysis Open system: exchanges of matter or energy
Example – a lake: water flows in as well as out
Closed system: no exchanges of matter or energy
Example – not as common; some underground cave systems
Which is Earth with respect to matter? How about energy?
Steady state systems
Input = output  system is not changing over time
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)