What are alkanes, alkenes, and alkynes?

1 Answer
Jun 6, 2018

Before understanding each of these 3 types, you need to know that alkanes, alkenes & alkynes are hydrocarbons .

Explanation:

Hydrocarbons are organic compounds which only consist of carbon (CC) and hydrogen (HH) as their elements.

Alkanes are a group of acyclic, saturated hydrocarbons. These are contain carbon - carbon (C-CCC) single bonds. The single bond is made up of one sigmaσ (sigma) bond.
Their general formula is C_nH_(2n+2)CnH2n+2 . [Here, nn stands for the number of carbon atoms].
Each atom has an sp^3sp3 hybridization in an alkane. The hydrogen atoms are always linked to a carbon atom.

-> Examples : Methane (CH_4CH4, where n=1n=1); Butane* (C_4H_10C4H10)

Alkenes and alkynes are unsaturated hydrocarbons.

Unsaturated hydrocarbons are those in which you have atleast one carbon - carbon double bond (C = CC=C), or atleast one carbon - carbon triple bond.

In the case of alkenes , they have atleast one carbon- carbon double bond. Their general formula is C_nH_(2n)CnH2n. From the formula, you can notice that alkenes only have 2 HH atoms lesser than the corresponding alkane.
The carbon - carbon double ( C = CC=C) bond consists of one sigmaσ and one piπ (pi) bond.

-> Examples : Ethylene (C_2H_2C2H2) or ethene; Pentene (C_5H_10C5H10).

Alkynes are unsaturated hydrocarbons which have atleast one carbon- carbon triple bond. Their general formula is C_nH_(2n-2)CnH2n2. You can see that these have 2 hydrogen atoms less than their corresponding alkane.

-> Examples : Acetylene (called ethyne) i.e. C_2H_2C2H2;
Propyne (C_3H_4C3H4).

I hope this helps!