Question

Predict whether each of the following compounds is saturated or unsaturated as indicated by the name. (a) cyclohexene (b) cyclopropane

Short answer

Cyclohexene is unsaturated; cyclopropane is saturated.

Step-by-step solution

Identify the Type of Hydrocarbon

To predict if a compound is saturated or unsaturated, understand that alkanes (saturated) have only single bonds, while alkenes and alkynes (unsaturated) have double or triple bonds, respectively.

Analyze Cyclohexene

In the name 'cyclohexene', the suffix '-ene' suggests the presence of a double bond, indicating that cyclohexene is an unsaturated hydrocarbon.

Analyze Cyclopropane

The name 'cyclopropane' uses the suffix '-ane', meaning it is a saturated hydrocarbon comprised solely of single bonds.

Key concepts

Alkenes

Alkenes are fascinating hydrocarbons that contain at least one carbon-carbon double bond. This is what sets them apart from alkanes, which only have single bonds between carbon atoms. The presence of a double bond means that alkenes are unsaturated compounds. They have fewer hydrogen atoms bonded to the carbon chain compared to their alkane counterparts.

The simplest alkene is ethene (also known as ethylene), with just two carbon atoms and a double bond. Ethene is crucial in industries, often used to produce plastics. Its formula is written as \\(C_2H_4\).

• Characteristic of alkenes is their general formula, \\(C_nH_{2n}\), indicating that the number of hydrogen atoms is doubled the number of carbon atoms.
• The double bond in alkenes gives them unique chemical properties, such as the ability to participate in reactions like polymerization and addition reactions.
• The presence of the double bond in alkenes can affect the geometry of the molecule, often resulting in planar regions around the double bond.

Recognizing alkenes is simple if you spot the suffix '-ene' in their names, as it indicates unsaturation due to the double bond. Alkenes play a prevalent role in both nature and in synthetic chemistry, with various applications ranging from adhesives to the production of alcohols.

Alkanes

Alkanes represent one of the most straightforward categories of hydrocarbons. They only contain carbon and hydrogen atoms linked by single bonds, making them saturated. Each carbon atom forms four single covalent bonds, resulting in the maximum number of hydrogen atoms around the carbon chain.

Alkanes have the general formula \\(C_nH_{2n+2}\), which helps in determining the number of hydrogen atoms in the molecule given the number of carbon atoms. This formula reflects the full saturation with hydrogen, as no other types of bonds (like double or triple) can exist.

• Due to having only single bonds, alkanes are relatively non-reactive but are excellent fuels, such as methane (\(CH_4\)), the simplest alkane.
• They are present in natural gas and crude oil, which are refined to extract different forms of alkanes used in everyday life from cooking to heating fuels.
• The suffix ‘-ane’ in their names indicates that they are alkanes, like propane or butane, familiar in domestic gas cylinders.

Alkanes are significant due to their properties as energy sources and their chemical stability, which means they don’t easily partake in chemical reactions except under extreme conditions.

Hydrocarbons

Hydrocarbons are organic compounds composed entirely of hydrogen and carbon atoms. They are the fundamental building blocks for many organic chemicals and can be classified based on the types of bonds between carbon atoms. There are three main types of hydrocarbons:

• Alkanes: Saturated hydrocarbons with single bonds only.
• Alkenes: Unsaturated hydrocarbons with at least one double bond.
• Alkynes: Unsaturated hydrocarbons with at least one triple bond.

Each of these types has a distinct general formula that reflects its saturation level. Hydrocarbons are crucial in multiple industries, including fuel, pharmaceuticals, and plastics. The term 'saturated' means that the molecule carries the maximum possible number of hydrogen atoms, while 'unsaturated' indicates the presence of double or triple bonds, allowing for additional atoms to add in during reactions.

Hydrocarbons are essential for forming the basis for many complex molecules. They are usually derived from fossil fuels and provide significant energy sources through combustion. Their versatility also lies in their ability to form chains and rings, contributing to the vast array of organic compounds indispensable in chemistry and industrial applications.