Classes Of Functional Groups
Organic Chemistry deals mostly with carbon and hydrogens, also called hydrocarbons, but those groups which replace hydrogen and bonds with carbon to give a characteristic nature, unique of their own, to the hydrocarbon they are attached to, are called functional groups. All the compounds belonging to a functional group undergo reactions in a similar pattern and are known to have similar physical and chemical properties.
Characteristics Of Functional Groups
In organic chemistry, we encounter a number of special substituent groups which are attached to the hydrocarbon backbone. These groups impart certain characteristics to the molecule of which it is a part of and thus, become the highlight of that particular molecule.
IUPAC Nomenclature
In Chemistry, IUPAC stands for International Union of Pure and Applied Chemistry which suggested a systematic naming approach for the organic and inorganic compounds, as in the beginning stage of nomenclature one single chemical compound was named in many ways by which lead to confusion. The need for this approach aroused as the number of chemical compounds newly discovered were increasing (approximately 32 million compounds) and the basic concept of nomenclature i.e. the trivial nomenclature and the derived system of nomenclature failed to overcome the challenge. It is an important task to name a chemical compound systematically and unambiguously which reduces lots of confusion about the newly reported compounds.
Structure: A carbonyl group (C=O)
2. 
Structure: Bromine with a negative charge (Br⁻)
3. 
Structure: A bromine atom attached to an alkyl group
4. 
Structure: A three-carbon chain with a positive charge on the central carbon
**Explanation of Diagrams:**
1. **Option 1:**
- **Structure:** This represents a carbonyl group, typically found in ketones or aldehydes, where a carbon atom is double-bonded to an oxygen atom.
2. **Option 2:**
- **Structure:** This depicts a bromide ion (Br⁻), where bromine carries a negative charge.
3. **Option 3:**
- **Structure:** This shows an alkyl group attached to a bromine atom, illustrating an alkyl bromide.
4. **Option 4:**
- **Structure:** This represents a carbocation, a three-carbon chain with a positive charge on the central carbon atom.
**Answer:**
In this question, the correct answer is Option 2: **Bromide ion (Br⁻)**. Bromide ions are nucleophiles due to their negative charge and the presence of a lone pair of electrons, which makes them electron-rich species that donate electrons rather than accept them, thus they cannot act as electrophiles.
### Key Concepts:
- **Electrophiles** are species that accept electron pairs. They are typically positively charged or have a partial positive charge.
- **Nucleophiles** are species that donate electron pairs. They are typically negatively charged or have a lone pair of electrons.
For detailed explanations and examples, please refer to the electrophilicity and nucleophilicity sections in your organic chemistry textbook.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fa4b8199f-1785-4bf8-892f-b1973e07d452%2Fe825d6a8-3f90-4159-849e-4c9a2e668038%2F52elpx_processed.jpeg&w=3840&q=75)
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