Chemistry is the science that deals with the structure, composition, and properties of substances. It also includes studying how these substances undergo certain chemical changes and how they release or absorb energy during the transformation process.
Since chemistry provides a foundation for understanding basic as well as applied scientific disciplines at a fundamental level, it is often referred to as the central science.
In the 16th and 17th centuries (the era of early chemistry), one person could hope to have a detailed knowledge of all subfields of chemistry. However, science and technology have changed a lot since then. Modern chemistry can be broken into several key subdisciplines that emphasize the subsets of chemical concepts.
Below, we have listed several different types of chemistry that deal with certain aspects of the universe.
1. Physical Chemistry
Applying pure physics to chemical problems
Physical chemistry involves studying the behavior of substances at different scales, from macroscopic to subatomic levels. Unlike other branches, it mainly deals with the laws of physics underlying all chemical interactions. The goal is to measure, correlate, and describe the quantitative aspects of reactions.
To understand the nature of atoms and their bonds, it’s important to know how electrons are distributed around the nuclei of the atoms. These problems are handled by a specific subfield called quantum chemistry. It provides special laws and tools to determine what shape and how strong bonds are, how nuclei move, and how electrons change their shells.
Another important subfield is photochemistry, which studies how light interacts with matter. This is crucial for spectroscopy, a fundamental exploratory tool to determine the type of chemicals in a compound.
Since different substances interact with light differently, we can identify them based on how they interact with light. This has helped us know the composition of faraway celestial bodies like planets, comets, and asteroids.
Physical chemists use sophisticated equipment such as lasers, electron microscopes, nuclear magnetic resonance, etc. to analyze substances, develop techniques to test can characterize the properties of substances, develop theories about these substances, and discover their potential applications. They may also apply mathematical analysis on massive datasets and conduct simulations to predict how these substances will react over time.
2. Organic Chemistry
Studying molecules containing carbon and hydrogen
In organic chemistry, we learn about compounds that contain covalently bonded carbon atoms. Unlike other atoms, carbon has the unique ability to form chains with other carbon atoms and various elements such as nitrogen, oxygen, halogens, sulfur, and many more. It can form millions of organic compounds that may consist of any number of other elements.
This field of chemistry mainly deals with the chemical composition, structure, and physical properties of organic compounds. It also involves evaluating the chemical reactivity of organic compounds to understand their behavior.
Organic chemistry plays a crucial role in the development of common household chemicals, foods, and fuels. Advancements in this field have made several contributions to our society, such as the synthesis of polymers (which includes all plastics and rubbers), numerous medicines, and other useful compounds like ethanol and insulin.
Because all known life is based on organic compounds, many careers apply an understanding of organic chemistry, including pharmacologists, dentists, chemists, doctors, veterinarians, and chemical engineers.
3. Inorganic Chemistry
Image credit: libretexts.org
Covers non-carbon-based compounds
Inorganic chemistry deals with compounds that do not have a carbon-hydrogen bond. On Earth, there are about 100,000 known inorganic compounds (in contrast to 2 million inorganic compounds). This field aims to study the structure, composition, and behavior of these compounds.
Some common examples of inorganic compounds include silicon dioxide (used in solar cells and computer chips), sulfuric acid (used in fertilizers and household products), and sodium chloride (used as table salt). They all can be classified as bases, acids, oxides, and salts.
Synthesis of inorganic chemicals involves the transformation of raw materials and compounds. They can undergo four different types of chemical reactions namely combination, decomposition, single displacement, or double displacement reactions.
One of its rapidly growing subfields is organometallic chemistry, which bridges the gap between organic and inorganic chemistry. It covers compounds containing at least one bond between a metal atom and a carbon atom. Organometallic compounds are extensively used in research and as catalysts to improve the rates of chemical reactions, especially where target molecules are pharmaceuticals or polymers.
Overall, inorganic substances have a substantial impact on the world economy. They are used in various industrial processes and products, including pigmentation, surfactants, catalysis, coating, medicine, materials science, and electronic devices.
4. Analytical Chemistry
Working principle of a typical analytical instrument
Science of identifying and quantifying the data about the structure and composition of matter
Analytical chemistry uses advanced techniques and instrumentation to isolate specific compounds, identify those compounds, and determine the quantify of the compounds in a product.
It can be further divided into two fields: quantitative analysis and qualitative analysis. The former is used to determine the absolute value or relative quantity of one or more substances present in a compound. The latter deals with the determination of the quality of a specific compound, irrespective of its concentration or quantity.
For example, the detection of iron in magnetite is qualitative analysis, whereas, the measurement of the actual amount of iron (72.3% by mass) in magnetite is quantitative analysis.
Analytical chemistry is used in various areas of science. For example, it can be used to identify the unknown substances found at a crime scene, determine the amount of cholesterol in a blood sample, purify the engine oil, and much more. It has major applications in bioanalysis, clinical analysis, forensic science, materials analysis, and environmental analysis.
5. Nuclear Chemistry
Atomic nucleus emitting an alpha particle
Studying changes in the nuclei of atoms
Nuclear chemistry is concerned with changes in the nucleus of elements, which are the source of nuclear power and radioactivity. Some elements on Earth are radioactive. They spontaneously emit radiation (such as alpha, beta, or gamma radiation).
Unlike conventional chemical reactions that form compounds, nuclear reactions transform one element into another. This property is utilized in nuclear power plants to collect and store nuclear energy.
Modern nuclear chemistry (often called radiochemistry) has a wide range of applications, from designing radioactive methods for diagnostic medicine to studying the formation of elements in the universe.
In fact, the advances made by nuclear chemists have become so important that physicists, geologists, and biologists use nuclear chemistry as regular tools in their disciplines.
A combination of radiation chemistry and radiochemistry is used to analyze nuclear reactions such as fusion and fission. Nuclear fusion, in particular, emits enormous amounts of energy and is generally referred to as thermonuclear reactions. The Sun and other stars in the universe are actually giant fusion reactors. In these stars, hydrogen molecules (under tremendous pressure of gravitational forces) are fused into helium and heavier elements. During the reaction, massive energy is released in the form of light and heat.
Nuclear chemistry also covers the nuclear processes in non-radioactive areas of human activity. Nuclear magnetic resonance spectroscopy, for example, is widely used in physical chemistry, synthetic organic chemistry, and macromolecular chemistry.
Explores chemical processes that occur in or related to living organisms
Biochemistry involves studying chemical substances and processes that occur in animals, plants, and microorganisms; and changes they undergo during their lifetime.
Basically, it’s a laboratory-based science that brings chemistry and biology together. It focuses on what happens inside living cells and how they communicate with each other during growth or fighting illness. It primarily deals with the structures, functions, and interactions of biological macromolecules, such as carbohydrates, lipids, nucleic acids, proteins.
Although biochemistry is still a young science, having been known under the term only since the late 19th century, it has successfully explained living processes through structural biology, enzymology, and metabolism.
Biochemistry also describes tools and techniques required to understand the functioning of biological molecules. This includes traditional techniques like chromatography, western blotting, and co-immunoprecipitation analysis.
Overall, it overlaps with a range of scientific disciplines, including microbiology, genetics, medicine, plant science, and forensics.
Other Emerging Subfields
7. Computational Chemistry
Utilizes computer simulation to solve complex chemical problems
As the name suggests, computation chemistry uses computer simulation to calculate the structures and properties of compounds or groups of molecules. Although it’s not an exact description of real-life chemistry, chemical phenomena can be explained to a certain extent in an approximate quantitative or qualitative computational scheme.
Chemical scientists and engineers exploit the advances that occur in computing hardware and software and in new theoretical and mathematical approaches. Most of the discoveries are based on the utilization of massively parallel high-performance CPUs and GPUs to solve complex equations.
For example, simulations and calculations done on supercomputers have improved our understanding of copper-catalyzed cyclopropanation, zinc-catalyzed alkylation, rhodium-catalyzed hydrogenation, the origin of enantioselectivity in transition metal-catalyzed asymmetric synthesis, and various other processes.
8. Quantum Chemistry
Applying quantum mechanics to chemical systems
In simple terms, quantum chemistry is the study of very small particles. The field emerged with the discovery of subatomic particles — electrons, protons, and neutrons.
One of the main goals of quantum chemistry is to understand the electronic structure and molecular dynamics using the Schrödinger equations. In 1926, Erwin Schrödinger developed a mathematical equation that shows if you know the potential energy acting on an object, you can measure the wavefunction for the object. And once you have the wavefunction, you can determine the properties of that object.
However, the exact solution for Schrödinger’s wave equation cannot be obtained for larger atoms and molecules (containing more than one electron). Quantum chemistry seeks to simply assumption/approximation and increase the accuracy of the solution for small and large molecular systems.
The recent developments in quantum mechanical modeling methods, such as density functional theory, have made it possible to reach accuracies comparable to those obtained in experiments of moderate-size molecules.
Study of molecules in space and their interaction with radiation
Astrochemistry is the science that studies the chemical composition of matter in space and the processes that led to those compositions. It is applied to both the Solar System and the Interstellar medium.
Astrochemists, who are part astronomers and part chemists, analyze the molecules and ions in outer space to figure out what role they play in the composition of the universe. This includes the atoms and molecules that make up the gaseous matter of future asteroids, stars, and even entire solar systems.
They utilize different types of radio telescopes to detect electromagnetic radiation ejected by celestial bodies. Once you know the frequency of waves (radio, gamma, ultraviolet, or infrared waves), you can determine what molecules are in space in what quantities. The data is then merged with the information obtained from other fields like astrophysics and meteorology to better understand the origin of our universe.
Study of chemicals derived from plants
Phytochemistry deals with the chemical processes associated with plant life and the chemical compounds produced by plants. Its primary goal is to study phytochemicals — bioactive nutrient plant chemicals in vegetables, grains, fruits, and other plant foods that may provide health benefits beyond standard nutrition.
Phytochemicals are used in soft drinks, functional food, and numerous other food products that have good nutrient value and significant importance. Flavonoids, isoflavonoids, phytosterols, glucosinolates, limonoids, polyphenols, are some of the most common phytochemicals that provide substantial health benefits.
Phytochemists try to determine the structures of various secondary metabolites found in plants. They also study how these compounds function in plant and human biology.
There are many different types of compounds found in plants. Most of them can be grouped into four biosynthetic classes: terpenoids, polyketides, phenylpropanoids, and alkaloids.
11. Green Chemistry
Minimizing the use and production of hazardous/unwanted chemical processes and substances
Green chemistry is mainly concerned with the optimization and creation of chemical processes and products that aim to reduce (or completely remove) the toxic substances produced in the environment.
Unlike environmental chemistry, which focuses on the harmful effects of polluting chemicals on the environment, green chemistry focuses on lowering the consumption of nonrenewable resources and developing new techniques to prevent pollution.
In 1998, Paul Anastas (one of the founders of the field of green chemistry) published twelve principles that address various ways to minimize the health and environmental impact of chemical production. These principles are:
- Prevent waste
- Design processes that utilize the maximum amount of raw materials
- Avoid using toxic chemicals
- Design safer chemicals
- Design safer solvents and auxiliaries
- Make the chemical process energy efficient
- Use renewable feedstocks
- Minimize unnecessary production of derivatives
- Use non-toxic catalysts
- Use products that can be broken down into non-harmful substances
- Monitor the whole process in realtime so it can be halted before the formation of hazardous substances
- Minimize risks of explosions, fires, and accidental releases
Although these principles are not new, the extent to which they are being applied has led to intensified attention on this topic among the industrial, academic, and regulatory communities.
Frequently Asked Questions?
What are the major types of chemical reactions?
Many different types of chemical reactions occur in nature, but most of them can be divided into six groups: combination reaction, decomposition reaction, neutralization reaction, combustion reaction, displacement reaction, and precipitation reaction.
How many types of chemical bonds are there?
In chemistry, there are four primary types of bonding:
- Covalent bonds: Atoms bonded by sharing electrons
- Hydrogen bonds: interaction involving a hydrogen atom located between a pair of highly electronegative atoms
- Ionic bonds: Electrostatic attraction between oppositely charged ions
- van der Waals interactions: Intermolecular interactions that do not contain ions or covalent bonds
Who is known as the father of chemistry?
Jabir ibn Hayyan is known as the father of early chemistry. He introduced a systematic classification of chemical substances. He also figured out a way to obtain an inorganic compound (ammonium chloride) from organic substances (like blood, hair, and plants) by chemical means.
The title of father of modern chemistry goes to French chemist Antoine Lavoisier. In 1778, he recognized and named oxygen and explained the role of oxygen in combustion. Later, he established that water is a compound and not an element.
Lavoisier created the first extensive list of elements and helped to improve chemical nomenclature. In 1787, he estimated the existence of silicon. He also proved that matter could change its shape or form, but its mass always remains the same.