Question

Which of the following molecules are saturated? a. \(\mathrm{CH}_{3}-\mathrm{CH}_{3}\) b. \(\mathrm{CH}_{2}=\mathrm{CH}_{2}\) c. \(\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CH}_{3}\) d. \(\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}=\mathrm{CH}_{2}\)

Short answer

The saturated molecules among the given options are: a. \(CH_{3}-CH_{3}\) (ethane) c. \(CH_{3}-CH_{2}-CH_{2}-CH_{3}\) (butane)

Step-by-step solution

Identify the type of bond in each molecule

Analyzing each molecule, we can see the type of bond between carbon atoms for every option: a. \(CH_{3}-CH_{3}\): Single bond between carbon atoms b. \(CH_{2}=CH_{2}\): Double bond between carbon atoms c. \(CH_{3}-CH_{2}-CH_{2}-CH_{3}\): Single bonds between carbon atoms d. \(CH_{3}-CH_{2}-CH=CH_{2}\): Both single and double bonds between carbon atoms Step 2:

Determine the saturation of each molecule

Based on the presence or absence of double bonds between carbon atoms, we can determine which molecules are saturated or unsaturated: a. \(CH_{3}-CH_{3}\) (ethane) is saturated because it has all single bonds. b. \(CH_{2}=CH_{2}\) (ethene) is unsaturated because it has a double bond. c. \(CH_{3}-CH_{2}-CH_{2}-CH_{3}\) (butane) is saturated because it has all single bonds. d. \(CH_{3}-CH_{2}-CH=CH_{2}\) (but-1-ene) is unsaturated because it has a double bond. In conclusion, the saturated molecules in the given options are: a. \(CH_{3}-CH_{3}\) (ethane) c. \(CH_{3}-CH_{2}-CH_{2}-CH_{3}\) (butane)

Key concepts

Single and Double Bonds

A single bond in organic chemistry is a type of covalent bond where two atoms share one pair of electrons. This results in a stable and relatively strong type of linkage and is most commonly found between carbon atoms in organic compounds. When you come across the structure of a molecule like ethane (\(\mathrm{CH}_{3}-\mathrm{CH}_{3}\)), you'll notice that it contains single bonds between the carbon atoms. These molecules are considered stable, as the single bond is quite robust.

In contrast, a double bond consists of two shared pairs of electrons between atoms and is usually formed between carbon atoms, as seen in ethene (\(\mathrm{CH}_{2}=\mathrm{CH}_{2}\)). Double bonds are less stable than single bonds because of their geometrical configuration and the strain within the bond. These bonds are more reactive, playing a vital role in chemical reactions.

Understanding the presence or absence of single and double bonds in a molecule is essential for determining chemical properties and reactivity, which is crucial when discussing saturation levels.

Saturated and Unsaturated Compounds

Saturation in organic compounds refers to the presence of single bonds only, with no double or triple bonds between carbon atoms. When a compound contains only single bonds, it's termed 'saturated.' Saturated hydrocarbons, like ethane (\(\mathrm{CH}_{3}-\mathrm{CH}_{3}\)) and butane (\(\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CH}_{3}\)), are considered stable and less reactive because there are no double or triple bonds to break or react with other atoms or molecules.

On the other hand, unsaturated compounds contain at least one double or triple bond. This feature contributes to their increased reactivity as it allows the compound to add other atoms to the molecule by breaking the unsaturated bonds. Ethene (\(\mathrm{CH}_{2}=\mathrm{CH}_{2}\)) and but-1-ene (\(\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}=\mathrm{CH}_{2}\)) demonstrate unsaturation because of the double bonds.

The differentiation between saturated and unsaturated compounds is a significant concept because it affects how these compounds behave, how they are used in chemical reactions, and their roles in our everyday lives.

Hydrocarbon Structures

Hydrocarbons are made up entirely of carbon and hydrogen atoms. These form the backbone of organic chemistry and can be found in both saturated and unsaturated forms. Their structures can vary widely, ranging from simple ones like ethane (\(\mathrm{CH}_{3}-\mathrm{CH}_{3}\)) to more complex chains like butane (\(\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CH}_{3}\)) or alkenes like but-1-ene (\(\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}=\mathrm{CH}_{2}\)).

The structure of a hydrocarbon significantly influences its physical and chemical properties. Hydrocarbons like alkanes (single-bonded hydrocarbons, such as ethane and butane) are saturated, meaning they are relatively inert and only react under certain conditions. On the other hand, alkenes and alkynes, which contain double or triple bonds, are unsaturated and more reactive due to the presence of these weaker bonds.

Learning about hydrocarbon structures helps in understanding not just basic organic chemistry but also in fields such as biochemistry and materials science, where different types of hydrocarbons are used to create synthetic materials and address fuel needs. Understanding their saturation helps predict reactivity and stability, essential for their practical application.