Draw a three-dimensional structure for each compound, and star all asymmetric carbon atoms. Draw the mirror for each structure, and state whether you have drawn a pair of enantiomers or just the same molecule twice. Build molecular models of any of these examples that seem difficult to you.
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Asymmetric carbon atoms, or chiral centers, are carbon atoms bonded to four different substituents, leading to non-superimposable mirror images. These centers are crucial in determining the stereochemistry of a molecule, as they give rise to different spatial arrangements, known as stereoisomers. Identifying these atoms is essential for understanding the three-dimensional structure of organic compounds.

Enantiomers are a type of stereoisomer that are mirror images of each other but cannot be superimposed. They typically arise from molecules with one or more asymmetric carbon atoms. Enantiomers have identical physical properties in a symmetrical environment but can exhibit different behaviors in chiral environments, such as biological systems, making their distinction important in organic chemistry.

Molecular models are physical or digital representations of molecules that help visualize their three-dimensional structures. These models can illustrate the spatial arrangement of atoms, bond angles, and the presence of chiral centers. Building molecular models is a valuable tool for understanding complex organic compounds, especially when dealing with stereochemistry and enantiomeric relationships.