Chapter 11 CHEM 117 biochem

Covalent Bond

Carbon + another atom (sharing of electrons)

Ionic Bonds

inorganic + another atom (exchange e-)

inorganic ionic compound properties

crystals, water coluble, dissociation of ions (NaCl), higher m.p. and b.p., conduct electricity

organic molecule properties

not very water soluble, low m.p. and b.p., flammable

Carbon properties

• can bond with just about anything

• compounds 1-1 million

• 4a element (4 valence e-)

• hybrid orbitals sp3 → 4 available e- for bonding

normla alkane shape

straight chain, connect the dots

branched alkane

backbone carbons and substituents coming off

Hydrocarbons

• molecules contain only C and H

• Aliphatic (alkane, cycloalkanes, alkene, alkyne)

• Aromatics, contain Benzene ring

Substituted Hydrocarbons

1+ H has been replaced by a functional group

Functional group

• atom(s) primarily responsible for chem and phys property of a molecule

• OH = alcohol

• COOH = carboxylic acid

Saturated Hydrocarbons

• contain single bonded C-C

• contain most possible H atoms bound to carbon

• alkane family

Unsaturated Hydrocarbons

• contain double or triple bonded C-C

• alkene and alkyne families

Alkane names

1. methane (simplest, primary in nat. gas, efficient clean burning)

2. ethane (small part of natural gas)

3. propane

4. butane (isobutane same but branched)

5. pentane

6. hexane

7. heptane

8. octane

9. nonane

10. decane

Conformations of alakanes and isomers

• different arrangement in space

• structural isomers = same molecular form. diff structural form.(branched)

stereoisomers

• molecules w same molec. form and struct, but atoms arranged diff in space

• geometric isomers: cis (substituents on same side of ring) trans (substituent on diff sides of ring)

naming alkanes

prefix (# and identity of attached groups) - root (longest C chain) - ending (functional class)

Alkyl groups

• alkanes with 1 fewer H atom

• remove “-ane” and add “-yl”

Cycloalkanes

• hydrocarbons that have single bonds in a ring structure

• naming: add “cyclo” before parent name

Properties of alkanes

• homologous series (only differ by one CH2 unit)

• non polar

• no reactive functional groups, simple chem good solvent for wax, oil, fats

• low density, float on water

• m.p. and b.p. increase with increase chain length

• methane (physiologically inert)

• C2-C4 anesthetics

Hydrophobic vs hydrophilic

phobic: water hating, nonpolar

philic: water loving, polar

reactions of alkanes

• least reactive of all organic molecules

• combustion: oxidation of hydrocarbons in presence of excess molecular O, CH + O2 → CO2 + H2O, incomplete combustion produces deadly CO