Environmental Systems Chapter 2

“anything that occupies space and has mass” Matter “anything that occupies space and has mass” Atoms Molecules Periodic Table Atomic Number http://science.howstuffworks.com/laser1.htm

a. law of conservation of matter No atoms are ever destroyed or created, but the bonds may change between them a. law of conservation of matter - “ matter cannot be created or destroyed; it can only change form” Chemical Reaction: occurs when atoms separate from the molecules they are a part of or recombine with other molecules

Radioactivity Unstable isotopes are radioactive Radioactive decay a. spontaneous release of material from nucleus ex) Uranium-235 (235U) Half-life a. measurement of radioactive decay Uranium 235- broken down to thorium-231 to produce heat and used by nuclear power plants to produce steam that in turns generates electricity Half-life: time it takes for one-half of the original radioactive parent atoms to decay : helpful because some elements emit harmful radiation under decay which is why it’s helpful to know uraniums half-life which is thousands of years but it’s safe to have this waste stored properly

Chemical Bonds Covalent Bonds (sharing of e-) a. CH4 (methane) Ionic Bonds (transfer of e-) a. NaCl (salt) Hydrogen Bonds (unequal sharing of e-) a. weak b. H2O

Properties of Water Surface tension Capillary action Boiling and freezing point Acts as a solvent Surface tension: results from cohesion of water molecules at the surface of a body of water (insects walking on water) Capillary Action: allows water to move through tiny spaces Boiling point: 100 degrees C and 212 Far. Freezing point: 0 degree C and 32 Far http://environment.nationalgeographic.com/environment/photos/freshwater-insects/

pH Acid a. dissociates into positively charged H+ and negatively charged ions b. HNO3 and H2SO4 Base a. dissociates into negatively charged OH- ions and positively charged ions b. NaOH H2NO3: nitric acid H2SO4: sulfuric acid http://sanibelseaschool.org/classroom/ph

Organic Molecules Organic v. Inorganic Compounds Examples of Organic Compounds a. Carbohydrates b. Lipids c. Proteins d. Nucleic Acids

Energy “ability to do work, or transfer heat” Majority on Earth derives from the Sun

Forms of Energy Joule: basic unit of energy (J) Energy and Power a. energy-ability to do work power-rate at which work is done therefore, energy = power X time power = energy / time Units: kW and KWh kW-power kWh-energy Capacity of a turbine generating electricity is in power and the electricity in your you is kwh (energy).

Kinetic and Potential Energy a. Potential-stored energy not yet released ex) water behind a dam b. Kinetic-energy of motion ex) electricity created from water captured by dam

Energy Laws 1st Law of Thermodynamics a. “energy is neither created nor destroyed” b. ex) Dams 2nd Law of Thermodynamics a. “when energy is transformed, the quantity of energy remains the same but its ability to do work diminishes” 1st Law of Thermodynamics: Water behind a dam is potential energy but becomes kinetic when it comes rushing through the gates of the dam Potential energy found in firewood never goes away but it is transformed into heat energy when burned in a fireplace 2nd Law: There is kinetic energy in a moving car but it is turned into heat and sound energy as the tires create friction with the road, this heat that is created is called waste heat (example)

b. energy efficiency c. energy quality - high v. low quality energy d b. energy efficiency c. energy quality - high v. low quality energy d. entropy e. global circulation patterns powered by Sun Energy efficiency: ratio of the amount of work that is done to the total amount of energy that is introduced into the system in the first place Energy quality: the ease at which the energy can be used * high – has a convienent form so that it does not take too much energy to move it from place to place (gasoline) * low-example is wood (would take much more power to use it to power an automobile) Entropy: all systems move toward randomness rather than order; the randomness is entropy example-a dirty room and getting it cleaned

Systems Open System a. exchange of matter or energy across system boundaries ex) ocean Closed System a. matter and energy exchange across the boundaries does not happen ex) underground cave system Systems a. allow researchers to predict how changes to any part of the system will change the entire system Open system a. ocean: energy from sun enters the ocean warming the waters and providing energy for plants, sun evaporates water giving rise to tropical storms which give rain back to the surface Earth a. open in regards to energy b. closed in regards to matter because all material exchanges occur within the system due to gravitational field

Input a. additions to a system Output a. losses from the system

Steady State “inputs equal outputs so that the system is not changing over time” Allows us to know if the amount of a resource or pollutant is increasing, decreasing or staying the same Very important to know when conducting a system analysis

Feedbacks Positive Feedback Loop a. amplifies change b. births in regards to human population Negative Feedback Loop a. responds to a change by returning to its original state to reach homeostasis b. thermostat Feedback Means that the results of a process feed back into the system to change the rate of that process Adjustments in input or output rates