Question 1: What are isomers?
Solution: Isomers are compounds with the same molecular formula but different structural or spatial arrangements.
Question 2: What is structural isomerism?
Solution: Structural isomerism, also known as constitutional isomerism, occurs when compounds with the same molecular formula have a different connectivity of atoms.
Question 3: What are stereoisomers?
Solution: Stereoisomers are compounds with the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in space.
Question 4: How does the concept of isomerism help in understanding the properties of different compounds?
Solution: Isomerism can explain why compounds with the same molecular formula have different chemical and physical properties. These differences arise from variations in the structural or spatial arrangements of the atoms within the molecules.
Question 5: What are cis-trans isomers?
Solution: Cis-trans isomers are a type of stereoisomer where the spatial positioning of the atoms differs around a double bond or a ring structure. In cis isomers, similar or identical groups are on the same side, while in trans isomers, they are on opposite sides.
Question 6: What are optical isomers?
Solution: Optical isomers are a type of stereoisomerism where the isomers are mirror images of each other and cannot be superimposed. These isomers can rotate plane-polarized light in different directions and are therefore also called enantiomers.
Question 7: What is a racemic mixture?
Solution: A racemic mixture, or racemate, is an equimolar mixture of two enantiomers. It does not rotate plane-polarized light because the rotations caused by each of the enantiomers cancel each other out.
Question 8: How are tautomers related to isomerism?
Solution: Tautomers are structural isomers that can interconvert by moving a proton and a pi bond. This phenomenon is called tautomerism, which is a special type of functional group isomerism.
Question 9: What is conformational isomerism?
Solution: Conformational isomerism, or conformers, are different arrangements of atoms that are interconverted by rotation around single bonds.
Question 10: How are the physical properties of isomers different?
Solution: Physical properties such as boiling point, melting point, and density can vary between isomers due to differences in the shape and size of their molecules, which influence the strength of the intermolecular forces between them.
Question 11: What is a chiral molecule?
Solution: A chiral molecule is one that cannot be superimposed on its mirror image. This often involves a carbon atom with four different groups attached to it, which is called a chiral center or stereocenter.
Question 12: What is a diastereomer?
Solution: Diastereomers are a type of stereoisomer that are not mirror images of each other. Diastereomers often have different physical properties and can be separated in the lab.
Question 13: What is the difference between an enantiomer and a diastereomer?
Solution: Enantiomers are mirror images of each other and have identical physical properties except for the direction in which they rotate plane-polarized light. Diastereomers, on the other hand, are not mirror images and have different physical properties.
Question 14: What is functional group isomerism?
Solution: Functional group isomerism is a type of structural isomerism where the compounds have the same molecular formula but different functional groups.
Question 15: What is position isomerism?
Solution: Position isomerism is a type of structural isomerism where the compound’s functional group or substituent changes position on the parent carbon chain.
Question 16: What is chain isomerism?
Solution: Chain isomerism is a type of structural isomerism where the compounds have the same molecular formula but different arrangements or lengths of the carbon chain.
Question 17: What is geometrical isomerism?
Solution: Geometrical isomerism, also known as cis-trans isomerism, is a type of stereoisomerism where the spatial arrangement of groups differs around a bond, typically a double bond or a ring structure.
Question 18: How can one separate a racemic mixture into its individual enantiomers?
Solution: A racemic mixture can be separated into its individual enantiomers by a process called resolution. This often involves converting the enantiomers into diastereomers, which have different physical properties and can be separated, and then reconverting the separated diastereomers back into the enantiomers.
Question 19: What is E/Z isomerism?
Solution: E/Z isomerism is a type of stereoisomerism where the spatial arrangement of groups differs around a double bond. ‘E’ comes from the German word ‘entgegen’, meaning ‘opposite’, and ‘Z’ comes from ‘zusammen’, meaning ‘together’. E/Z isomerism is similar to cis-trans isomerism but can be applied to alkenes with three or four different groups attached to the double bond.
Question 20: What is an epimer?
Solution: An epimer is a type of diastereomer where the compounds differ in the configuration at only one stereogenic center. D-glucose and D-mannose, for example, are epimers.