1. CHEMICALS IN THE ENVIRONMENT

2. CHEMICALS CYCLE  Earth is a closed system – which means that all atoms on earth remain on earth, including carbon and nitrogen.  As organisms grow and eventually die, they use and release certain elements.  These elements are continuously recycled within the environment.

3. CHEMICALS CYCLE - Carbon  Carbon is the “backbone” of life.  Molecules existing as Carbon chains, such as starches, sugars, proteins, and other compounds make up life as we know it.  Carbon exists in several forms on earth. By understanding the Carbon Cycle, we can understand the importance of carbon.

4. CARBON CYLE

5. USES OF CHEMICALS carbon →limestone  Limestone (CaCO 3 : Calcium Carbonate) is a sedimentary rock composed of the remains of sea organisms such as coral and the shells of mollusks  Has great benefits in agriculture - neutralizing agent for soil and water.  Used as a building material  Used by organisms to create essential compounds such as sugars and proteins  Used as a raw material in the production of cement, glass and iron.

6. BENEFITS OF CHEMICALS carbon →limestone

7. USES OF CHEMICALS carbon → carbon dioxide  Essential in photosynthesis 6H2O + 6CO2 ----------> C6H12O6+ 6O2  Used as a refrigerant – Dry Ice  Used in fire extinguishers  Beverage Carbonation  Too much carbon dioxide in the atmosphere, some believe, is causing global warming

8. USES OF CHEMICALS carbon → carbonic acid  Carbonic acid is produced when carbon dioxide reacts with water CO 2 (gas)+H 2 O H 2 CO 3  Carbonic acid has been a factor in the problems associated with acid rain

9. CHEMICALS CYCLE - Nitrogen  Nitrogen is essential to life as well – it is used to produce proteins and nucleic acids (DNA).  Nitrogen makes up 78% of the earth’s atmosphere, however most organisms are unable to utilize Nitrogen while it is in the atmosphere.

10. NITROGEN FIXATION  In order to be used by plants, nitrogen must first be converted to a useable form - this is called Nitrogen Fixation  Nitrogen can be “fixed”, or made useable, in several ways 1.Biological Fixation - Nitrogen fixing bacteria exist in the soil and are able to capture Nitrogen from the air and convert it into a form that plants may use. 2.Atmospheric Fixation - Lightning can convert atmospheric nitrogen to a useable form 3.Industrial Fixation - man-made processes can convert nitrogen to useable forms.

11. CHEMICALS CYCLE - Nitrogen

12. NITROGEN CYCLE

13. PROBLEMS WITH NITROGEN  Too much Nitrogen in the environment can be hazardous.  Humans impact the amount of nitrogen by adding fertilizers, and generating industrial emissions.  Too much Nitrogen leads to eutrophication of lakes, acid rain, and health hazards especially to infants.

14. EUTROPHICATION  Too much Nitrogen (and Phosphorus) builds up in a body of water  This is usually due to runoff of fertilizers and other nitrogen products  The excess Nitrogen promotes algae growth - algal bloom  Bacteria feed on the dead algae. This activity depletes the lake of oxygen which is harmful to life in that body of water.

15. CITATIONS  Biology: The Science of Life: Ecosystems: The Role of Abiotic Factors. United Learning. 2003. unitedstreaming. 25 June 2007