What is the Difference Between Alkenes and Alkynes?

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The primary difference between alkenes and alkynes lies in the nature of the bonds between carbon atoms in these hydrocarbon compounds. Here is a comparison of alkenes and alkynes:

Alkenes:

  • Contain one or more carbon-carbon double bonds.
  • General formula: $$\ce{C{n}H{2n}}$$.
  • Hybridization of carbon atoms: $$sp^2$$.
  • Trigonal planar geometry.
  • No acidic hydrogen.

Alkynes:

  • Contain one or more carbon-carbon triple bonds.
  • General formula: $$\ce{C{n}H{2n-2}}$$.
  • Hybridization of carbon atoms: $$sp$$.
  • Linear geometry.
  • Acidic hydrogen present.

Both alkenes and alkynes are unsaturated hydrocarbons, meaning they contain fewer hydrogen atoms than an alkane with the same number of carbon atoms. They undergo addition reactions, such as hydrogenation, halogenation, and hydrohalogenation. Both classes of compounds are named in a similar fashion, with the longest carbon chain that contains the double or triple bond being used to name the molecule.

Comparative Table: Alkenes vs Alkynes

Alkenes and alkynes are both types of hydrocarbons, which are compounds made up of hydrogen and carbon atoms. The main difference between them is the type of carbon-carbon bond they contain: alkenes have double bonds, while alkynes have triple bonds. Here is a comparison table highlighting the differences between alkenes and alkynes:

Property Alkenes Alkynes
Carbon-Carbon Bond Double Triple
General Formula R²C=CR² R-C≡C-R
Naming Conventions Family ending is -ene Family ending is -yne
Physical Properties Lower density, lower boiling point, and lower melting point compared to alkanes and alkynes Lower density, lower boiling point, and lower melting point compared to alkanes and alkenes
Chemical Properties Undergo addition reactions, such as hydrogenation, halogenation, and hydrohalogenation Undergo addition reactions, such as hydrogenation, halogenation, and hydrohalogenation

Both alkenes and alkynes are considered unsaturated hydrocarbons, meaning they have fewer hydrogen atoms than a saturated hydrocarbon (alkane) with the same number of carbon atoms. They also share similar physical properties, such as lower density, boiling point, and melting point compared to alkanes.