Allotropy- The substances which shows similar chemical characteristics but different physical characteristics are called allotropes and this property of material is called allotropy. Carbon has three allotropes – Charcoal, Graphite and Diamond
Properties of Diamond
• Diamond is an allotrope (different form) of carbon.
• The word diamond comes from the Greek word meaning unbreakable.
• The carbon atoms in diamonds are arranged in a strong, tetrahedral structure.
• Diamond is the hardest natural material known and is often used for industrial cutting and polishing tools.
• Diamond has a hardness of 10 on Mohs scale of mineral hardness, with 1 being the softest (talc) and 10 being the hardest.
• Diamond is the best known thermal conductor (heat transfer) among naturally occurring substances.
Properties of Graphite
• Graphite is a soft, slippery, grayish-black substance. It has a metallic luster and is opaque to light.
• Specific gravity of graphite is 2.3.
• Graphite is a good conductor of heat and electricity.
• Although graphite is a very stable allotrope of carbon but at a very high temperature it can be transformed into artificial diamond.
• Chemically, graphite is slightly more reactive than diamond.
Farms of amorphous carbon obtained by destructive distillation-
1. Wood Charcoal – obtained from wood
2. Sugar Charcoal – Obtained from cane sugar
3. Bone or animal charcoal – obtained from animal bones
4. Coke Charcoal – Obtained from Coal
Hydrocarbon – Hydrocarbons are chemical compounds made of hydrogen and carbon atoms only. The natural source of different types of hydrocarbons is petroleum.
Types of Hydrocarbons – Hydrocarbons are of grouped as:
• Saturated hydrocarbons
• Unsaturated hydrocarbons
• Aromatic Hydrocarbons
Saturated Hydrocarbons - Saturated hydrocarbons (alkanes) are the simplest of the hydrocarbon species and are composed entirely of single bonds and are saturated with hydrogen. The general formula for saturated hydrocarbons is CnH2n+2 (assuming non-cyclic structures). Saturated hydrocarbons are the basis of petroleum fuels and are found as either linear or branched species.
Hydrocarbons with the same molecular formula but different structural formulae are called structural isomers.
Unsaturated Hydrocarbons - Unsaturated hydrocarbons have one or more double or triple bonds between carbon atoms. Those with double bond are called alkenes. Those with one double bond have the formula CnH2n (assuming non-cyclic structures). Those containing triple bonds are called alkynes, with general formula CnH2n-2.
Cycloalkanes- Cycloalkanes are hydrocarbons containing one or more carbon rings to which hydrogen atoms are attached. The general formula for a saturated hydrocarbon containing one ring is CnH2n.
Aromatic Hydrocarbons - Aromatic hydrocarbons, also known as arenes, are hydrocarbons that have at least one aromatic ring.
Example of Hydrocarbons - Hydrocarbons can be gases (e.g. methane and propane), liquids (e.g. hexane and benzene), waxes or low melting solids (e.g. paraffin wax and naphthalene) or polymers (e.g. polyethylene, polypropylene and polystyrene).
Polymerization – The simple molecule which combines to make a macro molecule is called polymer. The process by which simple molecule called monomers converted to polymers called polymerization.
Some of the examples of naturally occurring polymers are protein, nucleic acid, cellulose, starch, etc
Plastics – Plastics are cross linked polymers and very tough in nature. Lac is a natural plastic.
Plastics are of two types – Thermoplastics and Thermosetting Plastics
Thermoplastics - Thermoplastic, also known as a thermosoftening plastic, is a polymer that becomes pliable or moldable above a specific temperature, and returns to a solid state upon cooling.
Examples of Thermoplastics – Polyethylene, Polystyrene, Polyvinyl Chloride, Teflon etc
Thermosetting Plastics - Thermosetting plastics are simply plastics when moulded into shape and allowed to cool will not change shape when heated again they will char or burn an example of a thermosetting plastic is urea formaldehyde.