Presentation on theme: "CHAPTER 25 - CARBON AND ITS COMPOUNDS. Organic - pertaining to life Living or was once living Organic Chemistry - The chemistry of carbon compounds Carbon."— Presentation transcript:
Organic - pertaining to life Living or was once living Organic Chemistry - The chemistry of carbon compounds Carbon is well suited for life because it is the most versatile element in terms of bonding.
Carbon can form four bonds. They can be single, double or triple bonds. Carbon will not form diatomic molecules like other small atoms do. It can form long carbon chains containing strong, short, covalent bonds.
Allotropes forms of the same element that differ in their bonding There are several allotropes of carbon Diamond – tetrahedral network of carbon atoms (every atom is locked into place (hardness) Graphite – sheets can slide over each other (lubricant)
Amorphous carbon – charcoal, soot, coke Amorphous has not set arrangement of atoms. It has irregular patterns of high surface area, deep “caves” that can trap other molecules Fullerenes – spherical molecules (60 atoms) see page 807, mostly experimental at this point.
Hydrocarbons molecules that contain only hydrogen and carbon
Fossil Fuels Natural gas - mostly methane Crude oil - mixture of hydrocarbon chains from propane to butane, octane and longer Components separated using fractional distillation (see page 823) Coal - mostly impure carbon (coke - pure carbon from coal, charcoal - pure carbon from wood)
Types of Formulas (examples) Compound - hexane Empirical formula Molecular formula Structural formula Condensed structural formula
CLASSIFICATION OF ORGANIC COMPOUNDS ALKANES - Compounds that contain only hydrogen and single bonded carbons. (carbon chains surrounded by hydrogens) Named with an ane ending that is preceded with a prefix which gives how many carbons that are in the carbon chain. Memorize the IUPAC prefixes on page 816
BRANCHED ALKANES Give the name of the branch with a yl ending. Indicate the number of the branch (keep numbers as low as possible). Examples: Problem assignment # 1 (first side of sheet)
ALKANES SUBSTITUDED WITH HALOGENS Give the position of the halogen (F, Cl, Br, or I) and then give the name of the halogen with an "o" ending. 3-chloro-2-methylpentanebromochloroiodomethane
Conformational isomers - molecules with the same structure but with different bond rotation. Molecules with single bonds can rotate about the single bond. These are the same compound. They have the same melting point, the same boiling points and the same chemistry. The higher the temperature the faster they change back and forth from one form to the other. Example: cyclohexane (chair and boat conformation)
Structural isomers - molecules that have the same molecular formula but have different structural formulas. These are different compounds with different melting points and different chemistry Examples C 5 H 12 (pentane, 1 methyl butane, 2,2 dimethyl propane)
SUBSTITUTED ALKANES Fisher Projection - a way to show the 3- dementional character of a molecule. Examples: CHFClI A carbon that has 4 different groups bonded to it is called a chiral carbon. Enantiomers - (mirror image isomers) - two arrangements around a chiral carbon that cannot be rotated in such a way as to be superimposed on each other.
They are different molecules that have the same formula, same boiling points and much of the same chemistry. Their chemistry differs when they are reacting with molecules that also have chiral carbons. (biological systems) They also rotate polarized light in opposite directions. Vitamin C is an example of this type of molecule.
UNSATURATED HYDROCARBONS If the molecule is filled to capacity with hydrogen the compound is saturated (alkanes). If the molecule is cyclic, contains a double bond or contains a triple bond it is unsaturated. Saturated fats are from animals and are not good for you. Unsaturated fats are from plants.
Alkenes - contains a double bond. Alkynes - contains a triple bond. Use the same prefixes along with a number to give the position of the double or triple bond. Example: 1 propene, 1 propyne, 3 chloro 1 butene, 3 chloro 1 butyne
Hybridization and resonance A double bonded carbon has 3 groups around it (sp 2 hybridization) Two of the p orbitals combine with the s orbital to form three sp 2 hybrid orbitals. The remaining p orbital is left unchanged and lies perpendicular to the flat molecule. The overlap of the p orbitals forms a pi bond. Sigma bond is the direct overlap of hybrid orbitals
http://www.mhhe.com/physsci/chemistry/a nimations/chang_7e_esp/bom5s2_6.swf http://www.mhhe.com/physsci/chemistry/a nimations/chang_7e_esp/bom5s2_6.swf Resonance is when several pi bonds lie in the same plane and all overlap A pattern of alternating single and double bonds results in resonance. Examples: 1,3 pentadiene, benzene (1,3,5 cyclohexatriene)