The Branches of Chemistry | General Chemistry 1

Physical Chemistry

Physical chemistry is the study of how matter reacts, changes form, and transforms. It's all about energy! In essence, it is the study of how energy and matter behave. Physical chemists want to know why some chemical reactions happen more quickly than others, or what happens when you put two gases together under pressure?

The overlap between physical chemistry and molecular physics is vast. Physical chemists use calculus to derive equations, which are derived from the laws of thermodynamics or electromagnetics in order for them to create new chemical compounds with desired properties.

Physical chemistry is often associated with quantum mechanics and theoretical physics, but it actually has many connections to chemical engineering. The two disciplines share some similarities in how they work on a macroscopic scale; however, there's still plenty of room for specialization within their respective fields. The subfields of physical chemistry include:

  • Chemical Kinetics - The study of how fast a chemical reaction happens. It's often used to describe rates in terms, molality (amount), rate constants, or equilibrium constant for example molecules changing speeds as they react with each other - this comes from kinetic theory which gives insight on all aspects like velocities caused by collisions between particles.
  • Chemical PhysicsChemical physics is the study of chemical processes. It is more closely related to physics, as it uses techniques from atomic physics, molecular physics, and condensed matter physics to investigate how substances behave when they're formed into different phases or states in an experiment.
  • Electrochemistry – Chemists often study how a solution's chemical composition changes when electricity passes through it. Electrochemistry, also known as electrochemical engineering or redox chemistry involves two components: an electrode with either metal atoms on its surface that can conduct electricity more easily than other materials do; and an electrolyte - which maintains enough ions so they don't combine together too quickly but still have access to their electron donor from within the solvent at some depth below them (known commonly as "solution"). 
  • Femtochemistry – The femtochemistry field of physical chemistry studies chemical reactions that happen over a timescale relatively shorter than many other types of reactions. These reactions are so quick, in fact, they only last for 10-15 or 1⁄1 000 000 000 000 000 of a second; that is, one quadrillionth, or one-millionth of one-billionth at most! This span of time is also referred to as a "femtosecond," hence, the name.
  • Geochemistry – Geochemistry is the study of how substances are formed, changed over time, and reused in Earth's systems. Geologists use geochemical data like this when they're looking for new resources on other planets. 
  • Photochemistry – The study of photochemistry can be considered the periodic table for light. It's an intricate, microscopic world where atoms and molecules are constantly reacting with one another in efforts to absorb or emit various wavelengths according to their own individual dictates--and sometimes even against them! For example, chemists study how shining a UV laser on a compound changes its color. Or, how fluorescent compounds appear so much brighter under different types of light.
  • Quantum chemistry – Quantum chemistry is a branch of chemistry that utilizes quantum mechanics to study physical models and experiments on chemical systems.  This is done by looking at the mathematical models of molecules' arrangement when they react, absorb, or emit energy.
  • Solid-state chemistry – Solid-state chemistry is the study of synthesis, structure, and properties in solids. This branch can include materials that are non-molecular but still retain some degree of complexity to them like crystals or polymers. Solid-state chemists create new methods for making complex substances by combining simpler ones into larger structures with unique arrangements of atoms - this process creates completely novel material systems where none existed before!
  • Spectroscopy – The study of matter and its interactions with electromagnetic radiation. Radiative transfer theory helps us understand how energy moves through space, what it looks like on different scales (from large-scale structures all the way down to individual atoms).
  • Stereochemistry – Stereochemistry is the study of how molecules are structured with respect to their chemical components. The arrangement of atoms that make up a particular molecule gives it its unique shape, size, and properties.
  • Surface science – Surface science is the study of physical and chemical phenomena that occur at interfaces between different substances in different states, such as solid-liquid, solid-gas, solid–vacuum, and liquid-gas interfaces.
  • Thermochemistry – Thermochemistry uses information about the temperature of a substance to measure chemical reactions. The changes in entropy and enthalpy in the surrounding environment are used to quantify the value of bond energies and other constants in a chemical equation. 
  • Calorimetry – The study of heat changes in physical and chemical processes. The word "calorie" comes from the Latin term calor and means "to heat."  Through this branch of science, we can observe how much energy (in conversions) goes into or comes out over time at any given temperature difference.


Organic Chemistry

Organic chemistry is the study of all things relating to organic compounds. From their structure, properties, and composition down to how they react with other chemicals or evolve over time. A few examples of how we apply organic chemistry in everyday life include:

  • Gasoline comes from petroleum which is formed from ancient decaying organic material such as entire rainforests or dinosaurs. 
  • Caffeine found in coffee beans (among many other plants) has been used as a psychoactive drug to increase energy output when consumed.

In addition to these examples, there are many other ways we can apply organic chemistry in our everyday lives from the food we eat to the clothes we wear. The areas of study you may come across in organic chemistry include:

  • Biochemistry – Biochemistry is the study of the biochemical processes of living organisms. It includes everything from chemical reactions and interactions that take place within an organism, all way up to how genes work! Biochemists may also get involved with molecular biology which studies DNA-based life processes like cellular division. Biochemical activities can be divided into three major categories: structural biology, enzymology, and metabolism.
  • Neurochemistry – Neurochemistry is the study of neurochemical structures, such as lipids, nucleic acids, peptides, proteins, sugars, and transmitters. These chemicals are involved in forming a range from moods to personality traits by interacting with one another or other parts within our bodies such as neurons that let you know when it's time for lunch! In addition to studying their structures, chemists also examine their interactions and the roles they play in shaping, sustaining, and transforming the nervous system. 
  • Molecular biochemistry and genetic engineering – Molecular biochemistry and genetic engineering are the studies of genes and their heritage, as well as how they're expressed.  In other words, molecular biochemistry is the study of molecules and their interactions while genetic engineering is the chemical manipulation or recombination of DNA to acquire the desired result.
  • Bioorganic chemistry – Bioorganic chemistry is the study of compounds that are created or broken down in living organisms. This branch of science is cross-disciplinary of both organic and biochemistry.
  • Biophysical chemistry – Biophysical chemistry is the study of physical systems with biological components. It uses concepts from physics and chemistry to understand how these types of interactions impact biological systems and cellular processes in organisms, allowing for progress towards new medicines or treatments that target specific diseases by targeting their mechanisms rather than symptoms alone.
  • Medicinal chemistry – The study of medicinal chemistry is a discipline that uses the tools and principles from both organic and inorganic chemistries. To make drugs or other medicinal treatments, researchers must first understand how they will work at the molecular level and then engineer them so they can have the desired effect.
  • Organometallic chemistry – Chemists study the different ways that metals, including alkalines and transition metals, can bond with carbon atoms in organic molecules to form organometallic compounds. These chemical structures are often referred to as "metal-organic" compounds because they contain at least one metal-carbon bonding pair; however, some other types may also exist like boron, silicon, or tin.
  • Physical organic chemistry – The study of how the structure, reactivity, or other properties relating to organic molecules interrelate with each other. 
  • Polymer chemistry – This branch of chemistry draws on multidisciplinary concepts that deal with the chemical synthesis and chemical properties of polymers or macromolecules. 
  • Click chemistry - The process of click chemistry is a relatively new technique for linking with specific biomolecules. This can be used in bioconjugation, which allows the joining together of desired compounds and their molecular partners to create life-saving treatments or vaccines against various diseases like cancer!



Some disciplines are not so limited in scope as to be categorized with the aforementioned branches. Nevertheless, they are important and worthy of mention. These include:

  • Astrochemistry – To date, there is still much that we don't know about the origins and evolution of our universe. The study of astrochemistry is not just about finding out how some planets are able to support life but also focuses on the abundance and reactions of chemical elements in space.
  • Cosmochemistry – Not to be confused with astrochemistry. Cosmochemistry is the study of chemical composition and processes that led to those compositions. It's a fascinating field, with many unanswered questions still left for scientists in this area!
  • Computational chemistry - Computational chemistry is a branch of the sciences that use computers to calculate structures and properties for molecules, groups of molecules, or solids. Theoretical models are programmed into programs where they become algorithms -a set of step-by-step instructions on how these processes work together through various calculations based on math problems. 
  • Environmental chemistry – Environmental chemistry is a vast and interesting field that explores the chemical makeup of our environment: air, soil, and water. It also looks at how humans have impacted environmental processes in their quest for resources like energy or materials used to produce things they need. 
  • Green chemistry - The philosophy of green chemistry is to create products that use less hazardous substances. It promotes the idea for engineers and researchers to design with care in mind, so they can develop better designs without polluting our environment or risking people's health from exposure to dangerous chemicals being released into the environment.
  • Supramolecular chemistry – In recent years, chemistry has been moving away from a sole focus on molecules and towards studying complex chemical systems made up of many different molecular components or "subunits." Supramolecular chemistry is one such emerging field that studies how these assembled units interact with each other in order to create new properties.
  • Theoretical chemistry – Theoretical chemistry is a branch of science that focuses on the application and theoretical reasoning behind fundamental principles in order to better understand how molecules interact with one another. Quantum mechanics can be applied when dealing with chemical reactions, which has led many people into researching what exactly happens at atomic scales during this type of transformation; thus developing new ways for computers to help predict results more accurately than ever before! There is an overlap with condensed matter physics (which studies tiny particles) as well as molecular physics.
  • Wet chemistry - A form of analytical chemistry called "wet" since most tests are conducted in its liquid phase, wet chemistry is often used for determining the properties and reactions rates. You may also hear this field referred to as "bench chemistry" as testing & analysis is often conducted at lab benches.
  • Agrochemistry – Agrochemistry is a new area of research that bridges the divide between chemistry and biochemistry for agricultural production, processing raw products into foods and beverages as well environmental monitoring. Agricultural science has expanded greatly in recent years to accommodate these needs with innovations such as genetically modified organisms (GMOs).
  • Atmospheric chemistry – The atmosphere is a complex system that affects all living things on Earth. A major frontier in atmospheric science research lies with understanding how different gases behave within the planet’s natural environment and what this means for life on the planet. 
  • Chemical engineering – The discipline of chemical engineering is a branch of engineering that applies the physical sciences, life sciences, and mathematics with economics to processes converting raw materials into more useful or valuable forms.
  • Chemical biology – In the field of chemical biology, scientists strive to understand how different types and levels of chemicals can be applied in order to analyze or manipulate biological systems. In recent years there has been a rise within this discipline with many people working on projects such as designing novel enzymes that could convert carbon dioxide into energy through photosynthesis!
  • Chemo-informatics – The use of computers in informatics is an emerging field that has the potential to solve many problems for chemists. The complexity and nature of data make it difficult to work with, but by employing novel computer technologies like Artificial Intelligence (AI) or Machine Learning algorithms we may be able to replicate human-like thinking processes on these complex systems.
  • Flow chemistry – Flow chemistry is an emerging branch of science that studies chemical reactions in a continuous flow, not as stationary batches. The goal of this research aims to make it easier and more efficient than ever before by developing technologies with applications at macroprocessing equipment or industrially applied enzymes like ligases which are used on crops such as wheat fields.
  • Immunohistochemistry – Immunohistochemistry is a process of detecting molecules in cells that are specific to tissue. In this example, an antibody will bind with antigens on the surface and provide researchers information about what's happening inside certain organs or tissues; for instance, immunostains can help detect cancerous cells!
  • Immunochemistry – Not to be confused with immunohistochemistry. The immune system is a complex network of cells, proteins, and chemicals that work together to defend the body from outside influences. Immunochemistry studies how these components function within our bodies.
  • Chemical oceanography – Chemical oceanography is the study of how chemical elements behave in our oceans. These waters cover the vast majority of Earth's surface, but until recently they were largely unexplored territory for scientists because they're so deep. The chemical processes observed on land differ greatly due to pressures.
  • Materials science – An interdisciplinary field investigating the relationship between the structure of materials at atomic or molecular scales and their macroscopic properties.
  • Mathematical chemistry – One area of study that uses mathematics to model chemical processes in mathematical chemistry. It's an emerging branch of science dedicated primarily to applied math with applications in many areas, including drug design and quantum computing.
  • Mechanochemistry – This discipline studies how molecules interact with one another and their surroundings while being influenced by other factors such as temperature changes or pressure levels; it can be seen as an interaction between chemical engineering and mechanical engineering since both disciplines involve complicated systems made up of many parts that must work together in order for them all function properly at once
  • Molecular biology – The study of interactions between the various systems within a cell is molecular biology. It overlaps with biochemistry and has many practical applications, such as understanding how cells function or creating vaccines against diseases.
  • Molecular mechanics – One of the most important factors in understanding how molecules behave is by using classical mechanics. Molecular mechanics takes this idea and applies it to model systems made up mostly or entirely out of chemicals instead, which are typically much more complex because they have an incredibly wide range of different types for atoms available (just think about all those variations within every element). 
  • Nanotechnology – The field of nanotechnology is an exciting new area in science that has the potential to revolutionize our world. While it is not strictly focused on chemistry, it can cross paths often. It can be used for all sorts of things, from building tiny robots with fascinating capabilities who could one day help us explore space, or repairing broken machinery on Earth, even creating vaccines by engineering DNA. 
  • Petrochemistry – The study of petrochemistry is a fascinating subject that has been studied for decades. It helps us identify ways we can turn crude oil and natural gas into things like plastic containers, buildings materials, and other commonly used items.
  • Pharmacology – Pharmacology is the study of how drugs work and what their effects are on you. This includes both physical effects, as well as chemical reactions.
  • Phytochemistry – Phytochemicals are chemicals that come from plants. They're used for many purposes, like making medications or common products we use every day. 
  • Radiochemistry – Radiochemistry is the study of chemicals that emit radiation. Radioactive materials are used for medical imaging, nuclear power plants, and research labs around the world because they have many interesting properties which help scientists learn more about how our universe works.
  • Sonochemistry – Sonochemistry is the study of how sonic waves affect chemical systems. It has been used for years by some to diagnose illnesses, while others believe this technique will one day produce cures in medicine as well!
  • Synthetic chemistry – A chemical is any substance that consists of molecules. In synthetic chemistry, chemists spend their days trying to create new ones, so they can understand what happens when different substances interact with one another and other things in the world around them.