What the Matter?Chem Review

Questions for Today

• What are the common elements used in Environmental Science?

• What is an Ion and what are the common ions used in Environmental Science?

• How are acids and bases important in Environmental Science?

• What are common chemical compounds used in Environmental Science?

• What are feedback loops and how are they classified

What are the common elements used in Environmental Science?

• Matter is anything that has mass and takes up space.

• Two major types of matter:– Elements – Pure Substances

– Compounds – different elements held in fixed proportions

What are the common elements used in Environmental Science?

• Four Elements – Oxygen, Carbon, Hydrogen, and Nitrogen – make up about 96.3% of your body weight.– If we add up the market price per kilogram

for each element in someone weighing 150 lbs, the total value is approximately 120 dollars.

Elements Important to the Study of Environmental Science

What is an Ion and what are the common ions used in Environmental Science?

• An Ion is any atoms that has gained or lost an electron.

Ions Important to the Study of Environmental Science

Compounds in Environmental Science

• Two Types– Inorganic Compounds– Organic Compounds

• Organic Compounds– Hydrocarbons and chlorinated hydrocarbons– Simple carbohydrates– Macromolecules: complex organic molecules

• Complex carbohydrates• Proteins• Nucleic acids• Lipids

Compounds Important to the Study of Environmental Science

Parts of a System

• A system is a set of components that function and interact in some regular way.

• Parts of a system– Inputs– Flows or thoroughputs– Outputs

• Environmental scientists use computer modeling to analyze systems.

Fig. 2-10, p. 44

Heat

Energy Inputs Throughputs Outputs

Energyresources

Matterresources

Information

Economy

Goods andservices

Waste andpollution

Feedback Loops

• Systems respond to change through the use of feedback loops

• Two types of feedback loops:– Positive – process that increases change– Negative - process that decreases change

• Homeostasis

Positive Feedback Loops

• A feedback loop occurs when an output of matter, energy, or information, is fed back into the system as an input and leads to changes in that system.

• A positive feedback loops causes a system to change further in the same direction.

• Examples of Harmful Feedback loops:– Deforestation– Melting of Polar Ice Caps

• Examples of Beneficial Feedback Loops:– Blood Clotting– Ecological Succession

Fig. 2-11, p. 45

Decreasing vegetation...

...which causesmore vegetationto die.

...leads toerosion andnutrient loss...

Negative Feedback Loops

• Negative, or corrective, feedback loops causes a system to change in the opposite direction from which it is moving.

• Examples:– Thermostat– Recycling

Fig. 2-12, p. 45

House warms

Furnaceon

Temperature reaches desired settingand furnace goes off

Temperature drops below desired settingand furnace goes on

House cools

Time Delays

• Time Delays are a gap in time between the input of a feedback stimulus and the response to it.

• The results of deforestation or pollutants usually have a time delay before the system reaches a threshold, or tipping point, where the damage is irreversible.

Synergy

• Synergy is when two or more process interact so that the combined effects are greater than the sum of their separate effects.

• Harmful Example:– Smoking and Asbestos leading to Lung Cancer– Air Pollutant Cocktails

• Beneficial Example:– Writing your Congressmen (Cheesy, Huh?)