1. Chemistry of LifeOctober 18 & 19, 2012 Chemical Elements C.H.O.N.P.S. In the Atmosphere: Nitrogen (78.1%), Oxygen (20.9%) In the Human Body: Oxygen (65%), Carbon (19%), Hydrogen (10%), Nitrogen (3%), Phosphorus (1.2%), Sulfur (0.2%)

2. Chemistry of LifeOctober 18 & 19, 2012 Carbon  Found in ALL organic compounds  Organic Compounds – Carbon containing compounds produced by living things, except Hydrogencarbonates (HCO 3 - ), Carbonates (CO 3 2- ), and Oxides of Carbon (CO - & CO 2 )  Symbol “C” forms 4 covalent bonds with other atoms Ionic Bonds involve elements from opposite sides of the periodic table, where one element is positively charged and the other is negatively charged… these charged particles are called Ions.

3. Chemistry of LifeOctober 18 & 19, 2012 Hydrogen  Most Abundant Element in this Universe  Symbol “H” forms 1 covalent bond with another atom  Forms Hydrogen Bonds  Hydrogen Bonds – very weak bonds, much weaker than ionic and covalent bonds; force of attraction between a slightly positive Hydrogen (H δ+ ) and a slightly negative Oxygen (O δ- )

4. Chemistry of LifeOctober 18 & 19, 2012 Oxygen  Most abundant element found in Human Body  Symbol “O” forms 2 bonds with other atoms Commonly found in its gaseous form O 2

5. Chemistry of LifeOctober 18 & 19, 2012 Nitrogen  Most abundant element in the Earth’s atmosphere  Symbol “N” forms 3 covalent bonds with other elements Nitrogen is a major component of Proteins (found in the amino group of Amino Acids) and Nucleic Acids (in the Nitrogenous Bases – Adenine, Guanine, Cytosine, Thymine, and Uracil)