# What are alkanes, alkenes, and alkynes?

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 ($C$) and hydrogen ($H$) as their elements.

Alkanes are a group of acyclic, saturated hydrocarbons. These are contain carbon - carbon ($C - C$) single bonds. The single bond is made up of one $\sigma$ (sigma) bond.
Their general formula is ${C}_{n} {H}_{2 n + 2}$ . [Here, $n$ stands for the number of carbon atoms].
Each atom has an $s {p}^{3}$ hybridization in an alkane. The hydrogen atoms are always linked to a carbon atom.

$\to$ Examples : Methane ($C {H}_{4}$, where $n = 1$); Butane* (${C}_{4} {H}_{10}$)

Alkenes and alkynes are unsaturated hydrocarbons.

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

In the case of alkenes , they have atleast one carbon- carbon double bond. Their general formula is ${C}_{n} {H}_{2 n}$. From the formula, you can notice that alkenes only have 2 $H$ atoms lesser than the corresponding alkane.
The carbon - carbon double ($C = C$) bond consists of one $\sigma$ and one $\pi$ (pi) bond.

$\to$ Examples : Ethylene (${C}_{2} {H}_{2}$) or ethene; Pentene (${C}_{5} {H}_{10}$).

Alkynes are unsaturated hydrocarbons which have atleast one carbon- carbon triple bond. Their general formula is ${C}_{n} {H}_{2 n - 2}$. You can see that these have 2 hydrogen atoms less than their corresponding alkane.

$\to$ Examples : Acetylene (called ethyne) i.e. ${C}_{2} {H}_{2}$;
Propyne (${C}_{3} {H}_{4}$).

I hope this helps!