1. Why is carbon considered tetravalent in organic chemistry?
Answer: Carbon has four valence electrons, allowing it to form up to four covalent bonds with other atoms, making it tetravalent.
2. Describe the shapes of simple organic molecules and the concept of hybridization involved.
Answer: Simple organic molecules often have tetrahedral or planar geometries due to the sp3 or sp2 hybridization of carbon atoms, respectively. Hybridization involves the mixing of atomic orbitals to form new hybrid orbitals suitable for bonding.
3. How are organic compounds classified based on functional groups?
Answer: Organic compounds are classified based on their functional groups, which are specific arrangements of atoms that determine the compound’s chemical behavior and properties. Examples include alkyls, alkenes, alkynes, alcohols, ethers, aldehydes, ketones, carboxylic acids, esters, amines, amides, and halides.
4. Define homologous series in organic chemistry.
Answer: A homologous series is a group of organic compounds with similar chemical properties and structural features, differing from each other by a repeating unit of CH2. Examples include the alkanes, alkenes, and alkynes.
5. Explain the concept of isomerism in organic chemistry.
Answer: Isomerism refers to the existence of two or more compounds with the same molecular formula but different structural arrangements or spatial orientations, leading to distinct chemical and physical properties.
6. Differentiate between structural isomerism and stereoisomerism.
Answer: Structural isomerism occurs when isomers have different structural arrangements of atoms, such as chain isomerism, positional isomerism, and functional group isomerism. Stereoisomerism occurs when isomers have the same structural formula but differ in spatial orientation, such as geometric (cis-trans) isomerism and optical isomerism.
7. Describe the nomenclature of organic compounds using the IUPAC system.
Answer: The IUPAC system assigns a systematic name to organic compounds based on the longest continuous carbon chain, the presence and position of substituent groups, and functional groups. It aims to provide a unique and unambiguous name for each compound.
8. What is meant by covalent bond fission in organic chemistry?
Answer: Covalent bond fission refers to the breaking of a covalent bond in a molecule, resulting in the formation of two species called radicals or ions.
9. Differentiate between homolytic and heterolytic bond cleavage.
Answer: In homolytic bond cleavage, each bonded atom retains one of the electrons from the bond, resulting in the formation of two radicals. In heterolytic bond cleavage, one atom retains both electrons from the bond, forming ions with opposite charges.
10. Define free radicals, carbocations, and carbanions in organic chemistry.
Answer: Free radicals are species with unpaired electrons, carbocations are positively charged species with an empty p orbital, and carbanions are negatively charged species with a lone pair of electrons on carbon.
11. Explain the factors influencing the stability of carbocations and free radicals.
Answer: The stability of carbocations and free radicals is influenced by factors such as resonance, inductive effects, hyperconjugation, and the nature of substituent groups attached to the carbon atom bearing the positive or unpaired electron.
12. What are electrophiles and nucleophiles in organic chemistry?
Answer: Electrophiles are electron-deficient species that seek electrons and tend to react with nucleophiles. Nucleophiles are electron-rich species that donate electrons and tend to react with electrophiles.
13. Describe the inductive effect and its role in electronic displacement in covalent bonds.
Answer: The inductive effect involves the polarization of a covalent bond due to the electronegativity difference between atoms, resulting in electron density being withdrawn or donated along the sigma bond.
14. What is the electromeric effect in organic chemistry?
Answer: The electromeric effect involves the movement of π-electrons in a conjugated system due to the migration of a substituent or charge, leading to the formation of resonance structures.
15. Define resonance in organic chemistry and its significance in molecular stability.
Answer: Resonance refers to the delocalization of electrons in a molecule or ion, leading to the formation of multiple resonance structures. It stabilizes molecules by distributing charge or electron density over multiple atoms.
16. What is hyperconjugation, and how does it contribute to molecular stability?
Answer: Hyperconjugation involves the delocalization of σ-electrons into adjacent empty or partially filled orbitals, such as p orbitals or π-systems. It contributes to molecular stability by dispersing electron density and lowering the overall energy of the molecule.
17. Discuss the common types of organic reactions: substitution, addition, elimination, and rearrangement.
Answer: Substitution reactions involve the replacement of one functional group or atom with another. Addition reactions involve the addition of atoms or groups to a multiple bond. Elimination reactions involve the removal of atoms or groups from a molecule. Rearrangement reactions involve the reorganization of atoms within a molecule to form a new structure.
18. How are organic compounds purified using chromatography?
Answer: Chromatography is a technique used to separate and purify organic compounds based on their differential distribution between a stationary phase and a mobile phase. Compounds are separated as they migrate through the stationary phase at different rates, depending on their interactions with the stationary phase and the mobile phase.
19. Describe the qualitative analysis techniques used to detect nitrogen, sulfur, phosphorus, and halogens in organic compounds.
Answer: Nitrogen is detected by the Dumas method or Kjeldahl method, sulfur by heating with sodium and testing for H2S gas, phosphorus by heating with nitric acid and testing for phosphoric acid, and halogens by heating with silver nitrate and observing the formation of a precipitate.
20. How are empirical and molecular formulae calculated for organic compounds?
Answer: The empirical formula represents the simplest whole-number ratio of atoms present in a compound and is determined by analyzing the compound’s elemental composition. The molecular formula represents the actual number of each type of atom present in the molecule and is calculated by comparing the compound’s molar mass to its empirical formula mass.