Carbon and Hydrocarbons

Organic Chemistry

Chapter 20.1 and 2

Abundance and Importance of Carbon

And Organic Compounds

1. Explain how the structure and bonding of carbon lead to the diversity and number of organic compounds.

2. Compare the use of molecular and structural formulas to represent organic compounds.

3. Compare structural and geometric isomers of organic compounds.

Objectives:

Earth’s crust17th in abundance by massFound in all living matter

Body tissue and foods we eatFound in Fuels

Coal, petroleum, natural gas, and wood

Group 14 elementMostly nonmetallic properties1s22s22p2 --- electron configurationsp3 hybridization promotes

Four bonding orbitals (sp3)

Carbon

1s 2s 2p

1s 2s 2p

CH4 – methaneTetrahedral shapeZigzag shape with multiple single bonds

C2H4 – etheneDouble bondsp2 hybrid

C2H2 – ethyneTriple bondsp hybrid

DiamondColorless, crystalline solidHardest material knownm.p. above 3500 oCConducts heat

Covalent network bondingUses: jewelry, cutting, drilling, grinding

GraphiteSoft, black, crystallineFair conductor of electricity (delocalized electron)Soft, feels greasyLess dense, strong – in sporting goods and aircraft

Hexagonal layersUses : pencil “lead”, lubricant

Allotropes of Carbon

FullerenesPart of soot formed when carbon – containing

materials are burned with limited oxygen.Near spherical cagesMost stable – C60

Also known as “buckyballs”

All organic compounds contain carbon atoms

Not all carbon-containing compounds are classified as organic.Ex: Na2CO3, CO, and CO2 are considered

inorganic.Organic compounds

defined as: covalently bonded compounds containing carbon, excluding carbonates and oxides.

Organic Compounds

Carbon-Carbon BondingThe diversity of organic compounds results from

the uniqueness of carbon’s structure and bonding

Form long chains and rings of covalently bonded atoms

Catenation covalent bonding of an element to itself to

form chains or ringsCarbon atoms can be linked by single, double,

or triple covalent bondsCarbon atoms bind readily to elements

with similar electronegativities

Carbon Bonding and the Diversity of Organic Compounds

Hydrocarbons Composed of only carbon and hydrogenSimplest organic compounds.

Other organic compounds contain hydrocarbon backbones to which other

elements, primarily O, N, S, and the halogens, are attached.

Bonding capabilities of carbon allow for many different arrangements of atoms

Some compounds may contain the same atoms but have different properties because the atoms are

arranged differentlyEX: the molecular formula C2H4O represents both

ethanol and dimethyl etherIsomers

Compounds that have the same molecular formula but different structures

Organic chemists use structural formulas to represent organic compounds.

Structural formula indicates the number and types of atoms

present in a molecule and also the arrangement of the atoms.

Ex: a structural formula for one isomer of C4H10 is the following

Condensed:

Structural Formulas

C C C

C

H

H

H

HH

H

HH

H

H

C C C

C

Structural formulas do not accurately show the 3-D shape of

molecules

Structural isomersalso called “constitutional isomers” atoms are bonded together in different orders

EX: the atoms of C4H10 can be arranged in two different ways:

Geometric isomers the order of atom bonding is the same but the

arrangement of atoms in space is different

Isomers

C C C

C

H

H

HH

H

HH

H

H

HC C C C

H

H

H

H

H

H

H

H

H

H

butane methylpropane

C C

Cl

H

Cl

H

C C

Cl

H

H

Cl

1,2-dichloroethene

cis trans