Question

(a) What structural feature is associated with each type of hydrocarbon: alkane, cycloalkane, alkene, and alkyne? (b) Give the general formula for each type. (c) Which hydrocarbons are considered saturated?

Short answer

(a) Alkanes: single bonds, Cycloalkanes: single bonds in a ring, Alkenes: one or more double bonds, Alkynes: one or more triple bonds. (b) Alkanes: C_nH_{2n+2}, Cycloalkanes: C_nH_{2n}, Alkenes: C_nH_{2n}, Alkynes: C_nH_{2n-2}. (c) Alkanes and Cycloalkanes.

Step-by-step solution

Identify Structural Feature of Alkanes

Alkanes are hydrocarbons with only single bonds between carbon atoms. They have the general structural formula: C_nH_{2n+2}.

Identify Structural Feature of Cycloalkanes

Cycloalkanes are hydrocarbons with carbon atoms arranged in a ring, with only single bonds between them. Their general structural formula is: C_nH_{2n}.

Identify Structural Feature of Alkenes

Alkenes are hydrocarbons that contain at least one carbon-carbon double bond. Their general structural formula is: C_nH_{2n}.

Identify Structural Feature of Alkynes

Alkynes are hydrocarbons that contain at least one carbon-carbon triple bond. Their general structural formula is: C_nH_{2n-2}.

General Formula for Each Type

The general formulas are as follows: Alkanes: C_nH_{2n+2}, Cycloalkanes: C_nH_{2n}, Alkenes: C_nH_{2n}, Alkynes: C_nH_{2n-2}.

Identify Saturated Hydrocarbons

Saturated hydrocarbons are those that have only single bonds between carbon atoms. Therefore, Alkanes and Cycloalkanes are considered saturated.

Key concepts

alkanes

Alkanes are a type of hydrocarbon that contain only single bonds between carbon atoms.
This means that each carbon in an alkane is bonded to four other atoms, either hydrogen or carbon.
Alkanes follow the general formula: \( C_nH_{2n+2} \).
As long as the number of carbon atoms (n) increases, the number of hydrogen atoms is always twice as many plus two.
Examples of alkanes include methane (\( CH_4 \)), ethane (\( C_2H_6 \)), and propane (\( C_3H_8 \)).
Because they only have single bonds, alkanes are considered saturated hydrocarbons.

cycloalkanes

Cycloalkanes are also hydrocarbons with only single bonds, but their carbon atoms are arranged in a ring structure.
This cyclic nature makes them a bit different from straight-chain alkanes.
The general formula for cycloalkanes is \( C_nH_{2n} \) which means each carbon is bonded to two hydrogen atoms, forming a closed loop.
Examples of cycloalkanes are cyclopropane (\( C_3H_6 \)), cyclobutane (\( C_4H_8 \)), and cyclohexane (\( C_6H_{12} \)).
Cycloalkanes are also considered saturated hydrocarbons because they do not have double or triple bonds.

alkenes

Alkenes are hydrocarbons that contain at least one carbon-carbon double bond, which changes their properties significantly.
The general formula for alkenes is \( C_nH_{2n} \), meaning they have the same number of hydrogen atoms as twice the number of carbon atoms.
The double bond makes alkenes more reactive compared to alkanes.
Examples include ethene (\( C_2H_4 \)), propene (\( C_3H_6 \)), and butene (\( C_4H_8 \)).
Because of the double bond, alkenes are considered unsaturated hydrocarbons.

alkynes

Alkynes are another type of hydrocarbon, characterized by at least one carbon-carbon triple bond.
This triple bond gives alkynes unique properties and makes them very reactive.
The general formula for alkynes is \( C_nH_{2n-2} \).
Examples of alkynes include ethyne, commonly known as acetylene (\( C_2H_2 \)), propyne (\( C_3H_4 \)), and butyne (\( C_4H_6 \)).
Due to the presence of the triple bond, alkynes are considered unsaturated hydrocarbons.

saturated hydrocarbons

Saturated hydrocarbons are those that have only single bonds between carbon atoms.
This means every carbon atom forms the maximum number of bonds possible with hydrogen atoms or other carbon atoms.
Both alkanes and cycloalkanes fall under this category because they only have single bonds within their structure.
Saturated hydrocarbons are generally less reactive compared to their unsaturated counterparts.
They are often found in many natural sources such as crude oil and natural gas.
Their simple bonding structure makes them an important class of compounds in organic chemistry.