carbon can form four covalent bonds = “tetravalence”
most frequent partners: H, O, N
shapes: tetrahedral (4 single bonds), bent, or linear
LE 4-3 Molecular Formula Structural Formula Ball-and-Stick Model Space-Filling Model Methane Ethane Ethene (ethylene)
Carbon Skeleton Variation
chains form the skeletons of most organic molecules
Carbon chains vary in:
Shape (branched or rings)
Animation: Carbon Skeletons
LE 4-5 Length Ethane Propane Butane 2-methylpropane (commonly called isobutane) Branching Double bonds Rings 1-Butene 2-Butene Cyclohexane Benzene
Hydrocarbons = consist of only C & H
Many organic molecules, such as fats, have hydrocarbon components
Hydrocarbons can undergo reactions that release a large amount of energy
Isomers = compounds with the same molecular formula but different structures and properties:
Structural isomers have different covalent arrangements of their atoms
Geometric isomers have the same covalent arrangements but differ in spatial arrangements
Enantiomers are isomers that are mirror images of each other
Enantiomers are important in the pharmaceutical industry
Two enantiomers of a drug may have different effects
Differing effects of enantiomers demonstrate that organisms are sensitive to even subtle variations in molecules
Investigation: L- Dopa L -Dopa (effective against Parkinson’s disease) D -Dopa (biologically Inactive)
Functional groups are attached to carbon skeleton & are the components most commonly involved in chemical reactions
The number and arrangement of functional groups give each molecule its unique properties
LE 4-9 Estradiol Testosterone Male lion Female lion
6 Functional groups
LE 4-10aa STRUCTURE (may be written HO—) NAME OF COMPOUNDS Alcohols (their specific names usually end in -ol ) Ethanol, the alcohol present in alcoholic beverages FUNCTIONAL PROPERTIES Is polar as a result of the electronegative oxygen atom drawing electrons toward itself. Attracts water molecules, helping dissolve organic compounds such as sugars (see Figure 5.3).
LE 4-10ab STRUCTURE NAME OF COMPOUNDS Ketones if the carbonyl group is within a carbon skeleton EXAMPLE Acetone, the simplest ketone A ketone and an aldehyde may be structural isomers with different properties, as is the case for acetone and propanal. Aldehydes if the carbonyl group is at the end of the carbon skeleton Acetone, the simplest ketone Propanal, an aldehyde FUNCTIONAL PROPERTIES
LE 4-10ac STRUCTURE NAME OF COMPOUNDS Carboxylic acids, or organic acids EXAMPLE Has acidic properties because it is a source of hydrogen ions. Acetic acid, which gives vinegar its sour taste FUNCTIONAL PROPERTIES The covalent bond between oxygen and hydrogen is so polar that hydrogen ions (H + ) tend to dissociate reversibly; for example, Acetic acid Acetate ion In cells, found in the ionic form, which is called a carboxylate group.
LE 4-10ba STRUCTURE NAME OF COMPOUNDS Amine EXAMPLE Because it also has a carboxyl group, glycine is both an amine and a carboxylic acid; compounds with both groups are called amino acids. FUNCTIONAL PROPERTIES Acts as a base; can pick up a proton from the surrounding solution: (nonionized) Ionized, with a charge of 1+, under cellular conditions Glycine (ionized)
LE 4-10bb STRUCTURE (may be written HS—) NAME OF COMPOUNDS Thiols EXAMPLE Ethanethiol FUNCTIONAL PROPERTIES Two sulfhydryl groups can interact to help stabilize protein structure (see Figure 5.20).
LE 4-10bc STRUCTURE NAME OF COMPOUNDS Organic phosphates EXAMPLE Glycerol phosphate FUNCTIONAL PROPERTIES Makes the molecule of which it is a part an anion (negatively charged ion). Can transfer energy between organic molecules.