Graduate
  1. Physical Chemistry  1.1. Thermodynamics  1.1.1. Laws of Thermodynamics  1.1.2. Enthalpy and heat capacity  1.1.3. Entropy and free energy  1.1.4. Phase Equilibrium  1.1.5. Statistical thermodynamics  1.1.6. Thermodynamic cycle  1.1.7. Fugacity and activity  1.2. Quantum Chemistry  1.2.1. Principles of quantum mechanics  1.2.2. Schrödinger Equation  1.2.3. Particle in a box  1.2.4. Operators and eigenvalues  1.2.5. Atomic orbitals  1.2.6. Molecular orbital theory  1.2.7. Perturbation theory  1.2.8. Valence bond theory  1.2.9. Hybridization and chemical bonding  1.3. Chemical kinetics  1.3.1. Rate laws and reaction mechanisms  1.3.2. Collision theory  1.3.3. Transition state theory  1.3.4. Enzyme Kinetics  1.3.5. Chain Reactions and Polymerization  1.3.6. Photochemical reactions  1.4. Statistical mechanics  1.4.1. Partitioning functions  1.4.2. Molecular distribution functions  1.4.3. Boltzmann Distribution  1.4.4. Bose–Einstein and Fermi–Dirac statistics  1.5. Spectroscopy  1.5.1. Rotational Spectroscopy  1.5.2. Vibrational Spectroscopy  1.5.3. Electronic Spectroscopy  1.5.4. Nuclear magnetic resonance spectroscopy  1.5.5. Mass Spectrometry  1.5.6. Raman Spectroscopy  1.5.7. Electron paramagnetic resonance spectroscopy  1.6. Surface and colloidal chemistry  1.6.1. Absorption isotherm  1.6.2. Surface tension and wetting  1.6.3. Colloidal Stability  1.6.4. Catalysis  1.6.5. Emulsions and micelles  1.7. Electrochemistry  1.7.1. Nernst equation  1.7.2. Electrochemical cells  1.7.3. Conductivity and mobility  1.7.4. War  1.7.5. Fuel cells  1.7.6. Electrolysis
  2. Organic chemistry  2.1. Reaction mechanism  2.1.1. Nucleophilic substitution reactions  2.1.2. Electrophilic addition reactions  2.1.3. Elimination reactions  2.1.4. Rearrangement reactions  2.1.5. Radical reactions  2.1.6. Pericyclic reactions  2.2. Spectroscopy and structural determination  2.2.1. UV-Vis Spectroscopy  2.2.2. IR Spectroscopy  2.2.3. NMR Spectroscopy  2.2.4. Mass Spectrometry  2.2.5. X-ray crystallography  2.3. Stereoscopic  2.3.1. Chirality and optical activity  2.3.2. Structural analysis  2.3.3. Geometrical isomerism  2.3.4. Dynamic Stereochemistry  2.4. Organometallic Chemistry  2.4.1. Organolithium and organomagnesium reagents  2.4.2. Palladium-catalyzed cross-coupling reactions  2.4.3. Transition Metal Complexes  2.4.4. Metal–carbon bond  2.5. Polymer chemistry  2.5.1. Polymerization mechanism  2.5.2. Polymer Characteristics  2.5.3. Biodegradable Polymer  2.5.4. Conducting polymer  2.5.5. Supramolecular polymers  2.6. Medicinal chemistry  2.6.1. Drug design and development  2.6.2. Pharmacokinetics and pharmacodynamics  2.6.3. Structure-activity relationships  2.6.4. Molecular docking and drug screening
  3. Inorganic chemistry  3.1. Coordination chemistry  3.1.1. Crystal field theory  3.1.2. Ligand field theory  3.1.3. Spectrochemical Series  3.1.4. Chelation and stability  3.2. Organometallic Chemistry  3.2.1. Metal Carbonyls  3.2.2. Catalysis by organometallic complexes  3.2.3. Metallocenes  3.3. Bio-inorganic chemistry  3.3.1. Metalloproteins and enzymes  3.3.2. The role of metals in biological systems  3.3.3. Metal ion transport and storage  3.4. Solid state chemistry  3.4.1. Crystal Structures  3.4.2. Band theory of solids  3.4.3. Superconductors  3.4.4. Defects in the crystal  3.5. Lanthanides and Actinides  3.5.1. Electronic configuration in lanthanides and actinides  3.5.2. Coordination chemistry of the lanthanides  3.5.3. Magnetic Properties of Lanthanides
  4. Analytical chemistry  4.1. Chromatography  4.1.1. Gas Chromatography  4.1.2. High Performance Liquid Chromatography  4.1.3. Thin Layer Chromatography  4.2. Spectroscopic Techniques  4.2.1. Atomic absorption spectroscopy  4.2.2. X-ray diffraction  4.2.3. Inductively coupled plasma spectroscopy  4.3. Electroanalytical methods  4.3.1. Potentiometry  4.3.2. Voltammetry  4.3.3. Colometry  4.4. Mass Spectrometry  4.4.1. Ionization Technique  4.4.2. Fragmentation Pattern  4.5. Chemometrics  4.5.1. Multidisciplinary analysis  4.5.2. Machine Learning in Chemistry
  5. Theoretical and Computational Chemistry  5.1. Molecular dynamics simulation  5.1.1. Force fields and energy minimization  5.1.2. Monte Carlo simulation in molecular dynamics simulations  5.2. Quantum chemical methods  5.2.1. Hartree–Fock theory  5.2.2. Density functional theory  5.2.3. Semi-empirical methods  5.3. Computational drug design  5.3.1. Molecular Docking  5.3.2. QSAR Modeling  5.3.3. Virtual Screening
  6. Biochemistry  6.1. Enzyme Kinetics  6.1.1. Michaelis-Menten kinetics  6.1.2. Inhibition mechanism  6.2. Metabolism and Bioenergetics  6.2.1. Glycolysis  6.2.2. Citric acid cycle  6.2.3. Electron transport chain  6.3. molecular Biology  6.3.1. DNA replication and repair  6.3.2. Protein synthesis  6.3.3. Gene Regulation  6.4. Structural Biochemistry  6.4.1. Protein Folding  6.4.2. Membrane Biophysics
  7. Environmental Chemistry  7.1. Atmospheric Chemistry  7.1.1. Greenhouse gases  7.1.2. Ozone depletion  7.1.3. Air pollutants and smoke  7.2. Water Chemistry  7.2.1. pH and water hardness  7.2.2. Wastewater treatment  7.2.3. Aquatic Chemistry  7.3. Soil Chemistry  7.3.1. Heavy metal contamination  7.3.2. Soil pH and Buffering  7.3.3. Nutrient cycling  7.4. Toxicology and Chemical Safety  7.4.1. Toxicokinetics  7.4.2. Risk Assessment in Toxicology and Chemical Safety in Environmental Chemistry  7.4.3. Effects of pollutants on the environment

Graduate → Physical Chemistry → Quantum Chemistry ↓


Hybridization and chemical bonding


Hybridization and chemical bonding are fundamental concepts in understanding the structure and behavior of molecules. In quantum chemistry, these ideas help us explain how atoms combine and form molecules with unique geometries and properties. This comprehensive guide aims to break down these complex topics into easily understandable terms, supported by textual explanations and visual examples.

Understanding chemical bonding

At the core of molecular structure is the concept of chemical bonding. Atoms achieve more stable configurations by bonding with one another. The primary types of chemical bonds include covalent, ionic, and metallic bonds:

  • Covalent bond: It involves the sharing of electron pairs between atoms. Covalent bonds occur mainly between non-metallic atoms. An example of this is the bond formation between two hydrogen atoms to form a hydrogen molecule (H2).
  • Ionic bonding: This involves the transfer of electrons from one atom to another, resulting in the formation of ions. An example of this is the bond in sodium chloride (NaCl), where sodium transfers one electron to chlorine.
  • Metallic bonding: This bond type is found in metals where electrons move freely in the lattice of metal cations, contributing to properties such as conductivity and malleability.

Molecular orbital theory

Molecular orbital (MO) theory provides a deeper understanding of how atoms combine atomic orbitals to form molecular orbitals. When atomic orbitals overlap, they form new orbitals where electrons can reside, these are molecular orbitals. According to MO theory, molecular orbitals can be bonding or restricting:

  • Bonding molecular orbitals: These arise from constructive interference of atomic orbitals and are lower in energy than the original orbitals. The electrons in these orbitals help to stabilize the molecule.
  • Antibonding molecular orbitals: These arise from destructive interference and have high energy. Electrons in these orbitals can destabilize a molecule.

A simple way to represent these concepts visually:

O_2 molecule: sigma* antibonding |________| | | * | | pi* antibonding |________| | | * | | * | | |________| | | pi bonding |________| | | * | | * | | |________| | | * sigma bonding The "stars" denote antibonding orbitals

Hybridization concept

Hybridization is a concept introduced to explain molecular geometry. It involves combining atomic orbitals to form new hybrid orbitals that are degenerate, or of equal energy. Hybrid orbitals can explain the shapes of molecules and predict the behavior of atoms in chemical compounds.

Types of hybridization

The different types of hybridisation are as follows:

  • sp Hybridization: This occurs when an s orbital and a p orbital combine to form two equivalent sp hybrid orbitals. This leads to linear geometry, as seen in BeF2 and acetylene C2H2. 
    BeF_2: Be: 1s^2 2s^1 2p^1 --> sp F-Be-F (linear geometry) sp sp FF ---|------------|---- 180°
  • sp2 Hybridization: In this one s orbital and two p orbitals combine to form three sp2 orbitals. This usually results in a trigonal planar structure as seen in BF3 and ethylene C2H4. 
    BF_3: B: 1s^2 2s^1 2p^2 --> sp^2 F | - B - F | F (Trigonal planar geometry) sp^2 sp^2 sp^2 F | | / --|-------|-- / 120°
  • sp3 hybridization: One s orbital and three p orbitals combine to form four equivalent sp3 orbitals that are tetrahedral in shape. Examples include CH4 and NH3. 
    CH_4: C: 1s^2 2s^1 2p^3 --> sp^3 H | - C - H | HH sp^3 H  H --|-------|-- 109.5°

Visualization of hybrid orbitals

To better visualize hybridized orbitals, consider the following example of sp^3 hybridized molecule, such as methane CH_4 :

CH_4: Tetrahedral example H | H---C---H | H The sp^3 hybrid orbitals arrange in a way that minimizes repulsion, resulting in a bond angle of approximately 109.5°.

Applications of hybridisation and bonding

The concepts of hybridisation and bonding are important in a number of chemical contexts:

  1. Organic chemistry: Understanding hybridization is essential for predicting the structure and reactivity of organic molecules.
  2. Inorganic chemistry: Transition metals often form complex ions where hybridisation can explain the unusual geometry.
  3. Materials science: Hybridization helps in designing new materials with specific electronic properties.

Conclusion

Hybridization and chemical bonding are fundamental to the field of chemistry, providing information about the structure and behavior of molecules. Through hybridization models, chemists can predict molecular geometry and bond angles. In particular, molecular orbital theory complements hybridization by describing how electrons are distributed within these molecules. Together, these concepts form the basis for understanding the vast and diverse world of chemistry.


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Hybridization and chemical bonding

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