1. The Chemical Basis of Life

3. Identify the following atoms

5. Ionic Bonding in NaCl

6. Crystal Structure of Sodium Chloride

7. Covalent Bonding

8. Water – a Polar Molecule

9. Cohesive Properties of Water Cohesion is the tendancy of molecules to stick together The strong cohesive properties of water due to hydrogen bonding give water, properties that are necessary for life to exist Transport of nutrients up very tall trees Surface tension allow for insects and other organisms to walk on water

11. Ice Why is this property of solid ice important to life?

12. Water as a Solvent

13. Water & Temperature Regulation Evapouration (sweat) Hydrogen bonds resist change in temperature (high heat capacity) Takes a large amount of energy to change temperature of water

14. Acidic & Basic Conditions Chemical reactions in organisms can usually only support a small range of pH To ensure that chemical reactions occur in a small pH range the body produces chemicals called buffers to maintain a constant pH

16. How do Scientists Elucidate Chemical Pathways? Through radioactive isotopes Isotopes are the same kind of atom with different numbers of neutrons Scientists used radioactive 14C (carbon- 14) to elucidate the chemical pathway of photosynthesis

17. Medical Diagnosis Radioactive isotopes may also be used to diagnose kidney disorders or cancer in the body when coupled with a PET scan (positron- emission tomography) Radioactive isotopes emit positrons that collide with electrons made through chemical reactions… –PET scans detect the energy released from the collisions –since cancer cells are more chemically active they will show more collisions on a PET scan

18. Normal vs Cancerous PET Scan

19. Dangers of Radioactive Isotopes Mutates DNA Destroys chemical bonds and creates abnormal bonds The 1986 explosion in Chernobyl caused 30 people to die within weeks, birth defects in developing fetuses and increased rate of thyroid cancer The 1999 accident in Tokaimura caused to deaths within weeks 46 people were exposed to high doses of radiation Natural sources of radioactivity also exists where rock formations contain naturally occurring uranium

20. Homework Read Chapter 2 Answer questions 1-24 pg 30-31 or page 64-65 in new book