Organic Chemistry

Organic Chemistry and Hydrocarbons

  • Organic chemistry is the study of carbon-based compounds, primarily hydrocarbons and their derivatives.
  • Hydrocarbons are organic compounds made up of hydrogen and carbon atoms only.
  • Hydrocarbons are classified into alkanes, alkenes and alkynes based on their bonds. Alkanes have all single bonds, alkenes have a double bond, and alkynes have a triple bond.
  • The general formula for alkanes is CnH2n+2, for alkenes is CnH2n, and for alkynes is CnH2n-2.
  • Hydrocarbons can be saturated (alkanes) or unsaturated (alkenes and alkynes). Saturated hydrocarbons have single bonds only (maximum hydrogen atoms), while unsaturated hydrocarbons have double or triple bonds.

Reactions of Hydrocarbons

  • Hydrocarbons participate in various chemical reactions, most notably combustion.
  • Combustion reactions involve the reaction of a hydrocarbon with oxygen to produce carbon dioxide and water, releasing energy in the process.
  • Substitution reactions occur with alkanes in the presence of UV light, where a hydrogen atom is replaced by a halogen atom.
  • Addition reactions, typical of alkenes and alkynes, involve the addition of substances such as hydrogen or halogens at the site of the double or triple bonds, resulting in single bonds.

Homologous Series

  • A homologous series is a series of compounds with the same functional group and general formula, differing by -CH2 groups.
  • Properties of compounds, such as melting point and boiling point, vary in a predictable way across a homologous series.
  • Members of a homologous series show gradual changes in physical properties, but similar chemical properties.

Isomers

  • Isomers are molecules with the same molecular formula but different structural arrangements.
  • Isomerism is significant in organic chemistry as it translates to unique physical and chemical properties for the compounds.

Functional Groups and Derivatives

  • Functional groups, such as -OH in alcohols and -COOH in carboxylic acids, dictate the chemical properties of organic compounds.
  • Compounds with the same functional group are often referred to as a family or class of compounds.
  • Hydrocarbon derivatives are compounds formed by replacing one or more hydrogen atoms in a hydrocarbon with a functional group.
  • Examples include alcohols, carboxylic acids, esters, and amides.

Polymers

  • Polymers are large molecules made by joining many small molecules (monomers) together.
  • There are two main types of polymers in organic chemistry, addition polymers and condensation polymers.
  • Polymers have a vast array of applications, including use in plastics, textiles, and resins.
  • Condensation polymers release a small molecule such as water during polymerization, while addition polymers do not.