 Chapter 2

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

 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: o Surface tension o Capillary action o Specific heat o Density of ice o Solubility

 Acids o Excess H+ ions in solution o NNO 3 (nitric acid) and H 2 SO 4 (sulfuric acid) o pH < 7  Bases o Excess OH- ions in solution o NaOH (sodium hydroxide) and Ca(OH) 2 (calcium hydroxide) o pH > 7

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

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

 Open system: exchanges of matter or energy o Example – a lake: water flows in as well as out  Closed system: no exchanges of matter or energy o Example – not as common; some underground cave systems  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)