carbon chemistry and polymers

Carbon Chemistry and Polymers

What is so unique about Carbon?

• Contains 4 valence electrons

• Can form single, double, or triple bonds

• Can bond with itself and many other elements

METHANE

Carbon has 4 valence Electrons

Carbon-Carbon Bonding

Types of Covalent Bonds

Long Chain of Carbon Monomers

Carbon Nanotubes

An example of Carbon-Carbon Bonding

Organic Compounds

• Contain carbon and hydrogen

• Often combine with O,N,P and S

• Millions of organic molecules, make up more than 90% of all known compounds

• Covalently bonded: C – C or C – H are the most common types of bonds

History of Organic Chemistry

• Until 1828, thought that there were only 2 types of molecules: Made by living organisms or man made

• Organic compounds were thought to be only made by living organisms

• Friedrich Wohler mixed Silver Cyanate with Ammonium Chloride to produce Ammonium Cynate

• Made UREA instead:

• AgOCN + NH4Cl (NH2)2CO + AgCl

Carbon can combine directly with itself as a pure element in three

different forms

DIAMOND

GRAPHITE

FULLERENE

Diamond, Graphite and Fullerenes

Diamond

• Hardest mineral• Forms deep within the

earth under very high pressure

• Hard, rigid , strong and unreactive

• Cutting is very hard need to break many covalent bonds

Graphite

• Extremely soft and slippery

• The “lead” in pencils( mixed with clay)

• Carbon is bonded tightly in flat layers

• WEAK bonds so layers SLIDE easily

Fullerene

• Discovered in 1985 in soot of burnt Carbon Compounds

• Has only 60 carbon atoms!!!

• Large hollow sphere or cage of carbon

• A use for fullerenes may be to carry substances like medicines inside of them

HYDROCARBONS

• Molecules made up Carbon and Hydrogen

• Simplest hydrocarbon is Methane CH4

• Made by the decomposition of living matter• Often found in swamps and marshes

•

Where do hydrocarbons come from?

• Primarily from coal and petroleum • Formed 290 to 354 million years ago from

decayed plant and animal material

Alkanes: saturated hydrocarbonsAll have single bonds

Formula = CnH2n+2

First 10 alkanes

Structural modelsStructural models

Isomers

• Same chemical formulas but different configurations.

• Will have Different properties !

"straight"

chain

C - C - C - C

branched

chain

C - C - C

|

C

Unsaturated Hydrocarbons

• Alkenes: contain at least one double bond

• Cn H2n

Alkynes: Contain at least one triple bond

• Formula is : CnHn

• Ethyne

Aromatic Compounds Benzene rings

Monomers

– Monomers are small, simple molecules, mostly organic, that can join with other similar molecules to form very large molecules, or polymers

Polymers

• Polymers are substances composed of multiples of simpler units called monomers.

• Polymers are extremely long chains with an unspecified number of monomer units.

PVC

Types of POLYMERS

• Determined by # of carbon atoms and how atoms are arranged

–Straight chain

–Branched chain

–Cross-linked

Types of Polymer Chains

Natural Polymers

• Carbohydrates• Proteins• Fats• Silk • Cotton• Cellulose• Starch • DNA and RNA

• Chitin • Fingernails• Natural Rubber • spider webs are also

poly-peptides (proteins) and are natural polymers

More Natural Polymers

• cellulose (amylose and amylopectin) proteins silk

•polyhydroxyalkanoates (natural polyesters made by bacteria as food reserves) deoxyribonucleic acid (DNA)

Monomers of Natural Polymers

• Nucleotides DNA and RNA

• Monosaccharides Carbohydrates

• Amino Acids Proteins

Synthetic Polymers:

• Plastics • Nylon • Teflon • Elastic • Styrofoam • Cellophane • Polyurethane • Polyester • Acrylic

Straight chains

• Number of atoms in chain affects the boiling point

• More atoms, higher boiling point

Branched Chain

Polyethylene (branched polymer) magnified 15,000x

Ring Structures

Cross-linking

Crosslinking

• Cross-links are bonds that link one polymer chain to another

• They can be covalent bonds or ionic bonds

Crosslinkingpolymers

When polymer chains are linked together by crosslinks, they lose some of their ability to move as individual polymer chains. For example, a liquid polymer (where the chains are freely flowing) can be turned into a "solid" or "gel" by crosslinking the chains together.

Crude Oil Distillation Unit

OIL SPILLS

Hydrocarbon Combustion

• Combustion is a process that everyone has experienced. It is used to heat homes, to power automobiles, and even to produce electricity. Combustion is an exothermic reaction between oxygen and a hydrocarbon. Combustion requires a certain amount of heat to begin, but once started the reaction proceeds spontaneously generating water vapor and carbon dioxide along with large amounts of energy in the form of heat and light.

The Combustion Equation:

Complete Combustion of Methane:

CH4 + 2O2 CO2 + 2H2O

Methane + Oxygen Carbon Dioxide + Water

methane + oxygen        carbon monoxide + water.2CH4(g)  + 3O2(g)             2CO(g)   +   4H2O(l)

Incomplete Hydrocarbon Combustion

• http://science.howstuffworks.com/oil-refining4.htm