CARBON AND MOLECULAR DIVERSITY THE IMPORTANCE OF CARBON

CARBON AND MOLECULAR DIVERSITY

THE IMPORTANCE OF CARBON • ORGANIC CHEMISTRY-focuses on the study of carbon • ORGANIC MOLECULES-contain carbon • VITALISM-early 19 th century; belief in a life force outside the jurisdiction of chemical/physical laws • MECHANISM-shift from vitalistic thought; belief that all natural phenomena are governed by physical and chemical laws

CARBON ATOMS: VERSATILE MOLECULAR BUILDLING BLOCKS • THE CARBON ATOMS: – – – – Usually has an atomic number of 6 Therefore it has 4 valence electrons Completes its outer shell by forming 4 covalent bonds TETRAVALENT ELECTRON CONFIGURATIONS Carbon becomes central figure in large molecules Carbon can bond easily with many different elements’ LOOK AT THE FOUR MAJOR ATOMIC COMPONENTS OF ORGANIC MOLECULES

ATOMS CARBON BONDS EASILY WITH • • HYDROGEN OXYGEN NITROGEN CARBON

VARIATION IN CARBON SKELETONS • Covalent bonds link carbon atoms together in long chains that form the skeletal framework for organic molecules. These carbon skeletons may vary in: – LENGTH – SHAPE (STRAIGHT CHAIN, BRANCHED, RING) -NUMBER AND LOCATION OF DOUBLE BONDS THIS VARIATION IN CARBON SKELETONS CONTRIBUTES TO THE COMPLEXITY AND DIVERSITY OF ORGANIC MOLECULES

• HYDROCARBONS- molecules containing only carbon and hydrogen – Make fossil fuels from long dead organisms – Are hydrophobic because C-C and C-H bonds are nonpolar

ISOMERS • ISOMERS ARE COMPOUNDS WITH THE SAME MOLECULAR FORMULA BUT WITH DIFFERENT STRUCTURES AND HENCE DIFFERENT PROPERTIES • THERE ARE 3 TYPES OF ISOMERS – 1) STRUCTURAL-differ in the covalent arrrangement of their atoms – 2) GEOMETRIC-have the same covalent bonding, but differ in spatial relationships – 3) ENANTIOMERS-mirror images

3 TYPES OF ISOMERS

SMALL GROUPS OF ATOMS THAT ARE BONDED TO THE CARBON SKELETON OF ORGANIC MOLECULES -THEY HAVE SPECIFIC CHEMICAL AND PHYSICAL PROPERTIES -ARE THE REGIONS OF ORGANIC MOLECULES THAT ARE CHEMICALLY REACTIVE -THEY BEHAVE CONSISTENTLY -CREATE UNIQUE CHEMICAL PROPERTIES OF ORGANIC MOLECULES THEY ARE FOUND IN

HYDROXYL GROUP • Consists of a hydrogen atom bonded to an oxygen atom, which is in turn bonded to carbon (-OH) – Is a polar group; the bond between O-H is polar – Makes the molecule to which it is attached water soluble – Organic compounds with hydroxyl groups are called alcohols

CARBONYL GROUP • CONSISTS OF A CARBON ATOM DOUBLE-BONDED TO OXYGEN (-CO) – IS A POLAR GROUP – FOUND IN SUGARS – ALDEHYDE- THE CARBONYL IS AT THE END OFF THE CARBON SKELETON – KETONE- THE CARONYL IS AT THE END OF THE CARBON SKELETON

CARBOXYL GROUP • Consists of a carbon atom which is both doublebonded to an oxygen and single bonded to the oxygen of a hydroxyl group (-COOH) • Is polar and water soluble • The covalent bond between oxygen and hydrogen is so polar that the hydrogen reversibly dissociates as H+. • Since it donates protons, this group has acidic properties • Compounds with this functional group are called carboxylic acids

FUNCTIONAL GROUPS • AMINO GROUP AND CARBOXYL GROUP

THE AMINO GROUP • Consists of a nitrogen atom bonded to two hydrogens and to the carbon skeleton(-NH 2) • Is polar and water soluble • Acts as a weak base. The unshared pair of electrons on the nitrogen can accept a proton • Organic compounds with this functional group are called amines.

FUNCTIONAL GROUPS • AMINO GROUP AND CARBOXYL GROUP

THE SULFHYDRYL GROUP • Consists of an atom of sulfur bonded to an atom of hydrogen (-SH) • Help stabilize the structure of proteins • Organic compounds with this functional group are called thiols

THE PHOSPHATE GROUP • It is the dissociated form of phosphoric acid (H 3 PO 4) • Loss of two proton by dissociation leaves the phosphate group with a negative charge • Has acidic properties since it loses two protons • Polar and water soluble • Important in cellular energy storage and transfer (ATP)