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 → Environmental Chemistry ↓


Atmospheric Chemistry


Atmospheric chemistry is a branch of environmental chemistry that focuses on the chemical composition of the Earth's atmosphere and the reactions that occur within it. The atmosphere is a complex mixture of gases, aerosols, and suspended particles, and it plays a vital role in supporting life on Earth. Understanding atmospheric chemistry is essential to address challenges related to air pollution, climate change, and ozone depletion.

Components of the atmosphere

The atmosphere is composed primarily of nitrogen ( N 2 ) and oxygen ( O 2 ), which together make up about 99% of the atmosphere's volume. Other important gases include:

  • Argon ( Ar )
  • Carbon dioxide ( CO 2 )
  • Methane ( CH 4 )
  • Nitrous oxide ( N 2 O )
  • Ozone ( O 3 )
  • Water vapor ( H 2 O )

These gases have different effects on atmospheric processes. For example, carbon dioxide and methane are greenhouse gases that trap heat, contributing to the greenhouse effect and climate change.

Chemical reactions in the atmosphere

Numerous chemical reactions occur in the atmosphere, many of which are driven by the presence of sunlight. These reactions often involve radicals, which are highly reactive molecules with unpaired electrons.

Photochemical reactions

One of the most important sets of reactions in atmospheric chemistry are photochemical reactions, which are triggered by sunlight. An example of this is the formation of ozone in the stratosphere:

O 2 + Hv → 2O
O + O 2 → O 3

In these reactions, ultraviolet (UV) radiation breaks down molecular oxygen into individual oxygen atoms, which then react with other oxygen molecules to form ozone. This ozone layer is essential for protecting the Earth's surface from harmful UV radiation.

Ultraviolet radiation O 2 → O + O O + O 2 → O 3

Air pollution

Air pollution is produced when harmful substances are released into the atmosphere, adversely affecting human health, ecosystems, and the climate. Common air pollutants include:

  • Sulfur dioxide ( SO 2 )
  • Nitrogen oxides ( NO and NO 2 )
  • Particulate matter (e.g., PM 2.5 and PM 10 )
  • Carbon monoxide ( CO )
  • Volatile Organic Compounds (VOCs)

Example: Formation of acid rain

Acid rain is the result of air pollution. It is formed when sulfur dioxide and nitrogen oxides react with water vapor in the presence of oxygen to form sulfuric and nitric acids:

2SO 2 + 2H 2 O + O 2 → 2H 2 SO 4
4NO 2 + 2H 2 O + O 2 → 4HNO 3

These acids can accumulate on the Earth's surface, causing environmental damage, such as acidifying lakes and soil and harming wildlife.

SO 2 + H 2 O + O 2 → H 2 SO 4

Climate change and the greenhouse effect

The greenhouse effect is a natural phenomenon in which certain gases in Earth's atmosphere trap heat, keeping the planet warm enough for life. However, human activities have exacerbated this effect by increasing the concentration of greenhouse gases, resulting in global warming and climate change.

Major greenhouse gases

  • Carbon dioxide ( CO 2 )
  • Methane ( CH 4 )
  • Nitrous oxide ( N 2 O )
  • Water vapor ( H 2 O )
  • Ozone ( O 3 )

These gases absorb infrared radiation emitted from the Earth's surface and reflect it back, preventing heat from escaping into space.

Sunlight Earth's surface Infrared radiation

Carbon dioxide is emitted by the burning of fossil fuels, while methane is produced by agricultural practices and the decay of organic waste. Nitrous oxide is emitted from fertilizers and other sources.

Depletion of the ozone layer

The ozone layer located in the stratosphere is important for absorbing most of the sun's harmful ultraviolet radiation. However, this protective layer has been degraded due to human activities.

Role of CFCs

Chlorofluorocarbons (CFCs) were widely used as refrigerants and propellants, until it was discovered that they destroy the ozone layer. CFCs released into the atmosphere eventually reach the stratosphere, where they are broken down by UV radiation, releasing chlorine atoms:

CFCl3 + UV → CFCl2 + Cl

These chlorine atoms catalyze the destruction of ozone molecules:

Cl + O 3 → ClO + O 2
2ClO + O → 3Cl + O 2

This cycle continues, with each chlorine atom capable of destroying thousands of ozone molecules.

CFC + UV radiation → Cl Cl + O 3 → ClO + O 2

Measurement and monitoring

Monitoring atmospheric composition is important to understand changes and their impacts. A variety of techniques are used, including satellite observations, ground-based monitoring stations, and air sampling methods.

Example technology: Remote sensing

Remote sensing involves the use of satellites to collect data on atmospheric gases from space. These satellites use instruments to measure the spectrum of sunlight and emitted radiation from Earth's surface and atmosphere, allowing scientists to determine the concentrations of various gases.

By analyzing these measurements, researchers can track trends in greenhouse gas levels, ozone concentrations, and the distribution of air pollutants globally.

Conclusion

Atmospheric chemistry is a dynamic and important field of study in environmental science. It helps us understand how chemical processes in the atmosphere affect Earth's climate, air quality, and ecosystems. As we continue to face global environmental challenges, knowledge of atmospheric chemistry will be critical in developing strategies to mitigate and adapt to changes in our environment.


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Atmospheric Chemistry

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