Chapter 4 Carbon and the Molecular Diversity of Life
Organic Chemistry u The study of carbon compounds. Urea
Carbon’s versatility u Forms 4 covalent bonds. u Molecular shape is tetrahedral. u Bonds easily to itself.
Major Elements Of Organic Molecules u Carbon: +4 or -4 u Hydrogen: +1 u Oxygen: -2 u Nitrogen: -3
u The valences are the “rules” for building organic molecules.
Hydrocarbons u Organic molecules made of only carbon and hydrogen.
Examples
Isomers u Compounds with the same molecular formula but have different structures. u Result: Different molecular and chemical properties.
Which of these are isomers? No Yes No
Types Of Isomers 1. Structural 2. Geometric 3. Enantiomers
Structural Isomers u Different in covalent arrangements of their atoms. ButaneIsobutane
Geometric Isomers u Same covalent partnership but differ in spatial arrangements. u Arise from the inflexibility of double bonds.
Enantiomers u Molecules that are mirror images of each other. u Usually involve an asymmetric carbon.
Comment u Organisms are sensitive to even the most subtle variations in molecular architecture.
Example - Thalidomide u Cells can distinguish between two isomers. u One is an effective drug. u The other causes birth defects.
Functional Groups u A group of atoms attached to a carbon skeleton. u Have consistent properties. u Their number and kind give properties to the molecule.
Importance of Functional Groups
What to focus on: u Structure of the functional group u Properties of the functional group u Examples of molecules with the functional group
Aldehydes u A carbonyl group at the end of a carbon skeleton. Ex. - C=O | H u Sometimes written as - CHO
Ketones u A carbonyl group in the middle of a carbon chain. Ex. -C-C-C- || 0
Carboxylic Acids u Donate H + (acid). u Form many weak organic acids.
Summary u Be able to recognize isomers. u Know the seven functional groups and what properties they give to molecules.