| CHEMISTRY OF LIFE
Chapter 2 Act #1: Introduction: Why study chemistry in biology? Read pg. 36-39 Answer questions #1-5 Read pg. 40-43 Answer questions #1-5 Act #2: Bonding and Molecules Atoms are not usually found by themselves in the form of pure elements. They are normally combined with other atoms- either the same kind or different kinds. This combination of atoms is a compound. Atoms in a compound are held together by electrons. The stronger these atoms are held together the stronger the chemical bonds. Some atoms are held together by a single bond. This is shown by a single line connecting the atoms: H-H. Other atoms are held together by double bonds: O=O. A substance made up of atoms that are bonded together is called a compound. The smallest piece of a compound that still has the properties of that compound is called a molecule. 1) What kind of substance is formed when two or more atoms combine? 2) What do we call the electron forces that hold together atoms? 3) What is the difference between a molecule and a compound? Act #3: Molecular Models Get a box which contains ball and stick atom models. Please don�t lose any of the individual pieces. 1) Look carefully at the different colored atoms. Besides color and size, how do the atoms differ from each other? 2) What do these holes in the atoms represent? 3) What do the sticks represent? 4) Look at the ball, which represents the oxygen atom. How could the compound O2 be created? 5) Construct the following molecules: Water: H2O methane: CH4 Ammonia: NH3 iodine: I2 Oxygen: O2 Nitrogen: N2 In your notes write the name and formula of each molecule. NOTES ON THE OCTET RULE: Act #4: Organic Compounds �Organic compounds have a backbone of one or more carbon atoms to which hydrogen, oxygen, nitrogen, and other atoms are attached.� Let�s take a look at a simple carbohydrate: glucose. 1) Take a look at a carbon atom (using the model). How many chemical bonds can it form? 2) Glucose, a six-carbon sugar, can exist in two forms: a straight chain and a ring. Please sketch the ring onto your paper using on pg. 45. 3) Write down the chemical formula for glucose. EXTRA CREDIT: Create the ring version of glucose using the ball and stick models. Act #5: Fats or Lipids Fats or lipids look like long chains. They resist dissolving in water. There are different fats or lipids because of the different lengths of fatty acids. a) Draw an example of a fatty acid (pg. 46 text, fig 2.13). b) Draw an example of a fat or lipid. c) What does hydrophilic mean? d) What does hydrophobic mean? e) On your drawing of a fat or lipid, label the end that�s hydrophilic and the end that�s hydrophobic. f) How would fat molecules re-arrange themselves if they were thrown in with water? g) What�s the difference between a saturated and an unsaturated fat or lipid? Which do you suppose is better for you? Why? Act #6: Uses for Fats a) Give me 2 uses for fats or lipids in our body. b) Animal fats tend to be saturated. Bacon grease is an example. Why is bacon grease a SOLID at room temperature? c) Plant oils tend to be unsaturated. Vegetable oil is an example. Why is vegetable oil a LIQUID at room temperature? d) We can test for fats by rubbing any food item on a piece of paper. If the paper has a translucent look that means there a presence of fat in the food item. |