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Chapter 4.4: Organic and Biochemical Compounds Organic Compounds • Covalently bonded • Carbon compounds • Almost always contain hydrogen Organic molecules contain carbon, usually hydrogen, Aspirin contains acetylsalicylic acid, C9H8O4 And assorted other atoms may be included, like Oxygen, nitrogen, sulfur and phosphorus (notice all are nonmetals, so they form covalent bonds) Carbon has four valence electrons • So it will make four bonds with other atoms willing to share their electrons. • Including other carbon atoms! Naming rules Number of carbons • Meth- 1 • Eth2 • Prop- 3 • But4 • Pent- 5 • Hex6 1 Alkanes Naming for different types of bonds • -ane only carbon-carbon single bonds • Only single covalent bonds. • -ene contains a carbon-carbon double bond • Methane, CH4 • -yne contains a carbon-carbon triple bond Another way to look at methane • “Single bond” means that the carbon is sharing only one electron with each of the four hydrogen atoms. Propane • The “prop-” means three carbons • And the “-ane” means all single bonds Ethane, C2H6 Alkanes: Single carbon-carbon bonds • The two carbon atoms are only sharing one pair of electrons, one from each of the two carbon atoms. Alkenes • Double bonds (two carbons are sharing two pairs – four atoms) 2 Propene and Butene • propyne ethyne = triple bond • Two carbons sharing 3 pairs (6 electrons) Alcohols have an –OH group • One of the hydrogens is replaced by an – OH group. Since there are two carbons, this is ethanol. Polymers • Big molecules made of repeating units. • The units are attached to one another by bonds, like beads strung together on a necklace. Polyethene • Poly means “many” • So it’s a large molecule made up of a series of “ethenes” (C2H4) • Plastic in soda bottles, etc. made of long noodle-like chains of these units. • Each unit = monomer 3 Polymerization • Free Radical Propagation • click here to see how polymers are formed from individual ethene molecules Elasticity • Cross-linked (like chain link fences or tennis nets) are flexible, but snap back into shape. • Molecules in a rubber band are examples. Starch Shape of polymer determines properties. • Polyethene isn’t elastic, so when you crush bottle it doesn’t “bounce” back. • This is because the long noodlelike chains can be bent easily, but they slide and slip instead of springing back into shape. Carbohydrates • Glucose is a carbohydrate. Large polymers of sugars are carbohydrates, often called “starch”. Carbohydrates can be 100's of sugars long. Body breaks the larger molecules into smaller glucose “units” again during digestion. 4 Proteins • Made up of repeating units called • amino acids. •CHON and sometimes S! DNA • Adenine and • Thymine • Cytosine and • Guanine • CHONP 5