Question

What are the different classes of hydrocarbons?

Short answer

The main classes of hydrocarbons are alkanes, alkenes, and alkynes. Alkanes are hydrocarbons with only single bonds and are saturated. Alkenes contain a carbon-carbon double bond and can add additional atoms by breaking the double bond, thus they are unsaturated. Alkynes contain a carbon-carbon triple bond which gives them the ability to add four more atoms, making them also unsaturated.

Step-by-step solution

Alkanes

Alkanes are the simplest form of hydrocarbon. They consist of carbon atoms connected by single bonds, with the rest of the bonds being filled by hydrogen atoms. These are known as saturated hydrocarbons because they have the maximum number of hydrogen atoms, with each carbon atom forming four single covalent bonds.

Alkenes

Alkenes are hydrocarbons which contain a carbon-carbon double bond. Because of this, they are considered unsaturated hydrocarbons as they can add additional atoms by breaking the double bond. The general formula for alkenes is \(\ C_{n}H_{2n}\ \).

Alkynes

Alkynes are hydrocarbons that contain a carbon-carbon triple bond. This gives them the ability to add four more atoms, making them also unsaturated. The general formula for alkynes is \(\ C_{n}H_{2n-2}\ \).

Key concepts

Alkanes

Alkanes are often known as the simplest and most fundamental type of hydrocarbons. Imagine a chain of carbon atoms where every carbon is joined with single bonds and surrounded by hydrogen atoms. These single bonds mean alkanes are saturated, holding the maximum number of hydrogen atoms possible.
This makes them quite stable and non-reactive compared to other hydrocarbons. Some examples of alkanes include methane (CH₄), ethane (C₂H₆), and propane (C₃H₈).

• Structure: Only single bonds between carbon atoms.
• Formula: General formula is \( C_nH_{2n+2} \).
• Characteristics: Saturated hydrocarbons, generally less reactive.

Alkanes are mainly found in natural gas and petroleum and can be useful as fuels due to their stability and energy-rich properties.

Alkenes

Alkenes introduce something more exciting into the mix—a double bond between carbon atoms. This double bond makes alkenes unsaturated hydrocarbons. Why? Because they have the potential to break that double bond and attach more atoms.
The simplest alkene is ethene (C₂H₄), commonly known as ethylene. This is a key molecule in the production of plastics.

• Structure: Contains at least one carbon-carbon double bond.
• Formula: General formula is \( C_nH_{2n} \).
• Characteristics: Unsaturated, more reactive than alkanes due to the double bond.

Alkenes are important in the chemical industry, serving as the groundwork for many synthetic processes.

Alkynes

Alkynes take things up a notch with a carbon-carbon triple bond. This makes them even more unsaturated than alkenes. With a triple bond, these hydrocarbons can potentially add four more atoms, making them highly reactive.
The simplest alkyne is ethyne (C₂H₂), also known as acetylene, often used in welding torches.

• Structure: At least one carbon-carbon triple bond.
• Formula: General formula is \( C_nH_{2n-2} \).
• Characteristics: Unsaturated, even more reactive due to the triple bond.

Alkynes play a crucial role in organic synthesis and are used to create various important chemicals and materials.