Question

Draw Lewis structures of these organic molecules: (a) methanol \(\left(\mathrm{CH}_{3} \mathrm{OH}\right) ;\) (b) ethanol \(\left(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}\right)\); (c) tetraethyllead \(\left[\mathrm{Pb}\left(\mathrm{CH}_{2} \mathrm{CH}_{3}\right)_{4}\right]\), which was used in "leaded" gasoline; (d) methylamine \(\left(\mathrm{CH}_{3} \mathrm{NH}_{2}\right)\) (e) mustard gas \(\left(\mathrm{ClCH}_{2} \mathrm{CH}_{2} \mathrm{SCH}_{2} \mathrm{CH}_{2} \mathrm{Cl}\right)\), a poison- ous gas used in World War I; (f) urea \(\left[\left(\mathrm{NH}_{2}\right)_{2} \mathrm{CO}\right]\), a fertilizer; (g) glycine \(\left(\mathrm{NH}_{2} \mathrm{CH}_{2} \mathrm{COOH}\right)\), an amino acid.

Short answer

Lewis structure sketches have to follow the molecular formula of the compounds. Each atom should have its appropriate number of bonds: Carbon normally forms 4 bonds, Hydrogen 1, Oxygen 2 or sometimes 1 (as in -OH), Nitrogen 3 or sometimes 4 and so on. The exact structures can be found in textbooks or through a simple internet image search, if needed for accuracy of the drawing.

Step-by-step solution

Drawing Methanol

Methanol \(\mathrm{CH}_3\mathrm{OH}\) consists of a Carbon atom (C) bonded to three Hydrogen atoms (H) and one Hydroxyl group (OH). Draw the C in the centre with an H or OH group at each of its four sides to represent the four single bonds.

Drawing Ethanol

Ethanol \(\mathrm{CH}_3\mathrm{CH}_2\mathrm{OH}\) includes two Carbon atoms bonded together. Beginning from the left, sketch the first Carbon bound to three Hydrogens. The next Carbon, on its right, bonds to two Hydrogens and an OH group.

Drawing Tetraethyllead

Tetraethyllead \(\mathrm{Pb}(\mathrm{CH}_2 \mathrm{CH}_3)_4\) has a central lead atom with 4 Ethyl groups (\( \mathrm{CH}_2 \mathrm{CH}_3 \)) bounded. Draw the Pb atom in the center, each of the 4 corners bonds with Ethyl groups.

Drawing Methylamine

Methylamine \(\mathrm{CH}_3\mathrm{NH}_2\) contains a central Carbon atom bound to three Hydrogens and one Amino group. Illustrate the C in the middle with three H's and the NH2 group around it.

Drawing Mustard Gas

\(\mathrm{ClCH}_2\mathrm{CH}_2\mathrm{SCH}_2\mathrm{CH}_2\mathrm{Cl}\) or mustard gas has two Carbon chains bonded by a Sulfur atom. Draw these in sequence, starting with a Chlorine atom, two carbon atoms, Sulfur atom, another 2 carbon atoms, and ending with a Chlorine.

Drawing Urea

The molecule for Urea or \(\left(\mathrm{NH}_2\right)_2\mathrm{CO}\) consists of a Carbon atom double bonded to Oxygen and single bonded to two Amino groups. Illustrate the Carbon atom in the middle, double bond it to an Oxygen atom, and single bond it to two NH2 groups.

Drawing Glycine

Last, Glycine or \(\mathrm{NH}_2\mathrm{CH}_2\mathrm{COOH}\) consists of an Amino group, a Carbon chain, and a Carboxyl group. Draw these sequentially, starting with the NH2, then the \(CH_2\), and ending with the COOH group.

Key concepts

Methanol

Methanol, also known as wood alcohol, is one of the simplest alcohols with the chemical formula \( \text{CH}_3\text{OH} \). In terms of structure, methanol consists of a single carbon atom (C) that forms bonds with three hydrogen atoms (H) and one hydroxyl group (OH). This results in four single bonds, with the carbon atom at the center acting as the backbone of this organic molecule.
To draw its Lewis structure, place the carbon atom in the center and arrange the three hydrogen atoms and one hydroxyl group around it. The hydroxyl group, consisting of an oxygen atom bonded to a hydrogen atom, is critical because it is responsible for the properties characteristic of alcohol compounds.

• Methanol is utilized widely as an industrial solvent, antifreeze, and fuel.
• Its simple structure makes it a key subject of study in organic chemistry.

Ethanol

Ethanol is a well-known organic molecule with the formula \( \text{CH}_3\text{CH}_2\text{OH} \) and is most commonly recognized as the type of alcohol found in alcoholic beverages. It builds upon the structure of methanol, featuring two carbon atoms instead of one. The first carbon atom connects with three hydrogen atoms while the second carbon is bonded to two hydrogen atoms and an OH group.
This results in ethanol having a slightly larger molecular structure compared to methanol. The additional carbon atom makes a notable difference in the physical and chemical properties of ethanol. The presence of the hydroxyl group (OH) not only denotes its identity as an alcohol but also affects its polarity and reactivity.

• Ethanol is used as a solvent in various industrial applications.
• It also serves as a renewable fuel source, often referred to as bioethanol.

Organic Molecules

Organic molecules are the cornerstone of chemistry, characterized by carbon atoms bonded to other elements such as hydrogen, oxygen, and nitrogen. These molecules form the basis of life and make up the structure of living organisms. Organic chemistry is the study of these compounds and their transformations.
Organic molecules demonstrate versatility and form complex structures, including chains and rings. For example:

• Chains: Linear sequences of carbon atoms, like in alcohols and acids.
• Rings: Cyclic arrangements, seen in aromatic compounds and many biomolecules.

The diversity of organic molecules is vast, leading to numerous substances including fuels, plastics, and pharmaceuticals that are crucial in everyday life. Understanding their structure is key for advancements in both science and industry.

Methylamine

Methylamine, with the chemical formula \( \text{CH}_3\text{NH}_2 \), is an organic compound that contains both a primary amine group and a methyl group. Structurally, it's composed of a carbon atom bonded to three hydrogen atoms, similar to methane, and an amino group (NH2), making it an amine.
The presence of the amino group imparts different chemical properties compared to alcohols or hydrocarbons. Methylamine is a base and can participate in hydrogen bonding due to the lone pair of electrons on the nitrogen atom.

• It is frequently used in the production of pharmaceuticals and agrochemicals.
• Its distinct fishy odor is a result of the amine group, typical in many nitrogen-containing compounds.

Urea

Urea is a simple amide with the formula \((\text{NH}_2)_2\text{CO} \) and plays a crucial role in biology. It features a central carbon atom double-bonded to an oxygen atom and singly bonded to two amino groups (NH2). This configuration makes urea an important waste product of protein metabolism in many organisms.
Its structure allows it to dissolve readily in water, making it essential in the process of removing nitrogenous waste from the body through urine.

• Urea is also employed as a fertilizer due to its high nitrogen content.
• It is utilized in the synthesis of plastics, adhesives, and several pharmaceuticals.

Understanding its Lewis structure highlights the connection between its chemical makeup and its functional uses.