Question

Draw the Lewis structure for each of the following functional groups: alcohol, aldehyde, ketone, carboxylic acid, amine.

Short answer

Draw each functional group identifying atoms and bonds, with lone pairs on heteroatoms.

Step-by-step solution

Understand Lewis Structures

Lewis structures represent the arrangement of electrons in a molecule. They display how atoms are bonded to each other, and the location of lone pairs of electrons.

Review the Functional Groups

Familiarize yourself with the common functional groups: alcohol contains an -OH group, aldehyde has a -CHO group, ketone features a carbonyl group (C=O) flanked by carbons, carboxylic acid contains a -COOH group, and amine includes an -NH2 group.

Draw the Lewis Structure of Alcohol

For alcohol, start with the main chain carbon and add the hydroxyl group (OH). Connect the oxygen to the carbon; the oxygen will have two lone pairs of electrons.

Draw the Lewis Structure of Aldehyde

Draw the carbon at the center with a double bond to oxygen (carbonyl group) and a hydrogen atom bonded to the same carbon. Add any remaining substituents.

Draw the Lewis Structure of Ketone

Place a carbon at the center with a double-bonded oxygen (carbonyl group). Attach carbon atoms on either side of the carbonyl, completing their valence with hydrogens.

Draw the Lewis Structure of Carboxylic Acid

Draw a carbon atom with a double bond to an oxygen (carbonyl group) and single bond to an OH group. The carbon will have either an additional bond to a carbon or hydrogen to complete its valency.

Draw the Lewis Structure of Amine

Draw a nitrogen atom single-bonded to one or more carbon atoms (NH2 group) or hydrogen atoms. Nitrogen should have one lone pair of electrons.

Key concepts

Understanding Functional Groups

Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. When learning about organic chemistry, it's crucial to understand functional groups because they greatly influence the chemical behavior of the molecules they are part of.
These groups are like the personality of molecules, defining how they'll react and fit into chemical transformations. Think of them as the building blocks or attachments that make each organic compound unique.

• Functional groups are the reactive parts of molecules.
• They determine the properties and reactions of molecules.
• Common functional groups include hydroxyl, carbonyl, carboxyl, and amino groups.

These components make organic molecules versatile and are key to understanding and predicting chemical behavior.

Exploring the Alcohol Functional Group

Alcohols are a type of organic compound that contains one or more hydroxyl (-OH) groups attached to a carbon atom. The presence of the hydroxyl group is what characterizes alcohols, making them uniquely polar and able to participate in hydrogen bonding.
This functional group is quite versatile and is found in everything from ethanol, used in beverages, to antiseptic wipes.

• Alcohols have the functional group -OH.
• The oxygen atom is bonded to a carbon and a hydrogen.
• The -OH group enhances solubility in water due to hydrogen bonding.

In Lewis structures, the -OH group is shown with the oxygen having two lone pairs, denoting its complete valency.

Understanding Aldehydes

Aldehydes are organic compounds that have a carbonyl group ( ext{C=O} ) bonded to at least one hydrogen atom. This gives aldehydes their distinct reactivity pattern and makes them useful intermediates in various chemical reactions.
They are often found in nature, contributing to flavors and aromas.

• Aldehydes feature the carbonyl group -CHO.
• The carbonyl carbon is bonded to a hydrogen.
• They play a key role in many biological processes.

In their Lewis structures, the central carbon in the -CHO group is double-bonded to oxygen and single-bonded to hydrogen, completing its valence.

Learning About Ketones

Ketones contain a carbonyl group ( ext{C=O} ) that is sandwiched between two carbon atoms. This placement enhances their stability and makes ketones important in various chemical and biological pathways.
Ketones are present in sugars and play critical roles in metabolism.

• Ketones have the functional group of a central carbon with a double-bonded oxygen.
• The carbon is flanked by carbon atoms.
• They are involved in energy processes, especially during fasting.

In their representation, the carbonyl group is typically shown in the middle, connecting to other carbon chains.

Understanding Carboxylic Acids

Carboxylic acids are organic acids characterized by a carboxyl group, ext{-COOH} . This means they include both a carbonyl and a hydroxyl group, providing both acidity and the ability to form hydrogen bonds.
These acids are ubiquitous in nature and are essential to many chemical and biological processes.

• Carboxylic acids have the functional group ext{-COOH} .
• They act as acids, donating protons ( ext{H} ^+ ).
• These are found in vinegar (acetic acid) and citrus fruits (citric acid).

In Lewis structures, the central carbon is bonded to an -OH group and a double-bonded oxygen, completing its tetrahedral structure.

Exploring Amines

Amines are derivatives of ammonia (NH₃) where one or more hydrogen atoms have been replaced by organic groups. This gives them a distinct, often fishy smell and makes them important in biological systems, particularly proteins.
Amines are basic and can participate in forming bonds with acids, making them critical in peptide bond formation in proteins.

• Amines consist of a nitrogen atom bonded to hydrogen and/or carbon atoms.
• Typically, amines have an -NH₂ group.
• They are fundamental in biochemistry, forming amino acids and neurotransmitters.

In their Lewis structures, nitrogen is depicted with one lone pair, highlighting its ability to participate in bonding further.