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Organic Chemistry

Molecular models for organic structure representation

Molecular models are tools used for classroom or research to visualize better and interpret three-dimensional structures of organic molecules. The toolkit can be made of wood, plastic, metal, or other materials.

These models are digitally represented using computer graphics covered under molecular modelling, a branch of chemistry that uses computational and theoretical methods to model and mimic the molecule's behaviour in chemical and biological environments.

Differences between Valence Bond (VB) and Valence Shell Electron Pair Repulsion (VSEPR) Theory

Valence Bond (VB) Theory

Valence Shell Electron Pair Repulsion (VSEPR) Theory

Valence Bond Theory explains how atoms combine to form di and polyatomic molecules held by covalent bonds.

VSEPR theory considers shape, molecular geometry, and bond angles as an after-effect of covalent bond formation. The molecules take up various shapes to overcome the electron repulsions between the bonding and nonbonding electrons of the combining atoms.

Difference Between Structural Isomers and Stereoisomers

Structural Isomerism

Stereoisomerism

Isomers have the same molecular formula but differ in how the atoms are bonded to each other.

Isomers have the same molecular formula and bonding arrangement; however, they differ in how the atoms are arranged in 3-dimensional space (spatial orientation) with respect to each other.

Such molecules that differ by bonds while still having the same molecular formula are also known as constitutional isomers.

Differences between Valence Bond Theory (VBT) and Molecular Orbital Theory (MOT)

Aspect

Valence Bond Theory (VBT)

Molecular Orbital Theory (MOT)

Basic Concept

Describes chemical bonding as the overlap of atomic orbitals, forming localized bonds.

Describes bonding by combining atomic orbitals into molecular orbitals that are delocalized over the molecule.

Bonding Explanation

Focuses on bonds as being localized between two specific atoms.