carbon and its compounds

• About Carbon:

  1. It is derived from the Latin word 'Carbo' which means coal.
  2. In the earth's crust, there is 0.02% of carbon present, and in the atmosphere, there is 0.03% of CO2.
  3. Most carbon compounds are poor conductors of electricity.
  4. The three main allotropes of carbon are diamond, graphite, and buckminsterfullerene.
• Reactivity of elements refers to their tendency to attain a completely filled outer shell, i.e., attain noble gas configuration.
• If carbon were to gain four electrons, it would be difficult for the nucleus with six protons to hold on to ten electrons.
• If carbon were to lose four electrons, it would require a large amount of energy to remove four electrons leaving behind a carbon cation with six protons in its nucleus holding on to just two electrons.
• Covalent bonds are formed by the sharing of electrons between two atoms so that both can achieve a completely filled outermost shell.
• Catenation is the ability of an atom to form bonds with other atoms of the same element.
• 1. Diamond is the hardest natural substance known.
  2. It is colourless and transparent.
  3. It is used for removing cataracts and cutting marble.
  4. It has a high melting point (3500°C).
  5. Each carbon is bonded to four other carbon atoms forming a rigid three-dimensional structure.
• 1. In graphite, each carbon atom is bonded to three other carbon atoms in the same plane giving a hexagonal array.
  2. It is smooth and slippery.
  3. It is a very good conductor of electricity.
  4. It has a high melting point (3650°C).
  5. It is used in pencils, lubricants, batteries, etc.
• 1. Buckminsterfullerene is a spherical carbon allotrope where 60 atoms are assembled in pentagons and hexagons.
  2. It consists of 20 hexagons and 12 pentagons.
  3. It was discovered by Richard Smalley, Robert Curl, and Harold Kroto in 1985.
• Saturated compounds are compounds of carbon which are linked by only single bonds between the carbon atoms.
• Unsaturated compounds are compounds having double or triple bonds between the carbon atoms.
• Tetravalency is the characteristic of carbon to form four covalent bonds.
• The reason for the formation of strong bonds by carbon is its small size which enables the nucleus to hold on to the shared pairs of electrons strongly.
• Compounds with identical molecular formula but different structures are called structural isomers.
• A homologous series is a group of organic compounds having similar structures and similar chemical properties in which the successive compounds differ by CH2 group.
• Combustion is the burning of a carbon compound in air to give carbondioxide, water, heat, and light.
• Substitution reaction is the reaction in which one or more hydrogen atoms of a hydrocarbon are replaced by some other atoms.
• 1. Ethanol is a colourless liquid which has a pleasant smell.
  2. It used as an active ingredient in alcoholic drinks and in medicines.
  3. It is soluble in water.
  4. Its structural formula is C2H5OH.
• Hydrogenation is the addition of hydrogen to an unsaturated hydrocarbon (in the presence of palladium or nickel) to obtain a saturated hydrocarbon.
• Ethanoic acid is commonly called acetic acid and belongs to a group of acids called carboxylic acids.
• 5-8% solution of acetic acid in water is called vinegar which is widely used as a preservative in pickles.
• The melting point of pure ethanoic acid is 290K and it often freezes during winter in cold climates which gave rise to its name glacial acetic acid.
• Rectified spirit is made up by a mixture of ethanol (95%) and water (5%)
• The reaction in which a carboxylic acid combines with an alcohol to form an ester is called esterification. It takes place in the presence of an acid catalyst.
• An allotrope is a form of an element that has the same chemical properties as the element but different physical properties.