5^th International Conference on Physical and Theoretical Chemistry October 11-13, 2018 Edinburgh, Scotland

Physical Chemistry is the branch of chemistry dealing with the physical properties of chemical substances. It is one of the traditional sub-disciplines of chemistry and is related with the application of the concepts and theories of physics to the study of the chemical properties and reactive behaviour of matter.

Electrochemistry is the branch of  chemistry which deals with the chemical changes caused in the matter by passage of electric current and conversion of chemical energy into  electrical energy and vice versa. Electrochemistry deals with the study of electrical properties of solutions of electrolytes and with the interrelation of chemical phenomenon and electrical energies. It is the study of production of electricity from energy released during impulsive chemical reactions and the use of electrical energy to bring about non-spontaneous chemical reactions. Electrochemistry is not only limited up to chemistry but its branches extend to physics and biology also.

Chemical physics is a sub field of chemistry and physics that investigates physicochemical phenomena using techniques from molecular and atomic physics and condensed matter physics; it is the branch of physics that studies chemical processes from the point of perspective of physics. While at the interface of physics and chemistry, chemical physics is distinct from physical chemistry in that it focuses more on the typical elements and theories of physics. Meanwhile, physical chemistry observes the physical nature of chemistry. Nonetheless, the distinction between the two fields is vague, and workers usually practice in both fields during the course of their research.

Chemistry, by its very nature, is related with change. Substances with well-defined properties are converted by chemical reactions into other substances with distinct properties. For any chemical reaction, chemists try to find out the practicality of a chemical reaction which can be predicted by thermodynamics, extent to which a reaction will continue can be determined from chemical equilibrium and speed of a reaction i.e. time taken by a reaction to reach equilibrium. Along with viability and extent, it is equally important to know the rate and the factors controlling the rate of a chemical reaction for its thorough understanding. For example, which parameters determine as to how rapidly food gets spoiled? How to design a rapidly setting material for dental filling? Or what controls the rate at which fuel ignites in an auto engine? All these questions can be answered by the branch of chemistry, which deals with the study of reaction rates and their mechanisms, called chemical kinetics.

Surface science is the study of physical and chemical phenomenon that occur at the interface of two phases, including solid–liquid interfaces, solid–gas interfaces, solid–vacuum interfaces, and liquid–gas interfaces. It includes the fields of surface chemistry and surface physics. Surface chemistry can be roughly defined as the study of chemical reactions at interfaces. It is closely associated to surface engineering, which aims at modifying the chemical composition of a surface by incorporation of selected elements or functional groups that generate various desired effects or improvements in the properties of the surface or interface. Surface science is of specific importance to the fields of heterogeneous catalysis, electrochemistry, and geochemistry.

Femtochemistry is the field of physical chemistry that studies chemical reactions on extremely short timescales, about 10−15 seconds. The steps in some reactions occur in the femtosecond timescale and sometimes in attosecond timescales, and will few times form intermediate products. These intermediate products cannot always be concluded from observing the starting and end products. Femtochemistry enables exploration of which chemical reactions take place, and investigates why few reactions occur but not others. The resolution in time of the elementary dynamics (femtochemistry) offers an opportunity to observe a molecular system in the continuous process of its evolution from reactants to transition states and then to products. Application of femtochemistry in biological studies has helped to elucidate the conformational dynamics of stem-loop RNA structures.

Spectroscopy is study of the absorption and emission of light and other radiation by matter, as related to the dependence of these procedures on the wavelength of the radiation. More recently, the definition has been expanded to include the study of the relations between particles such as electrons, protons, and ions, as well as their interaction with other particles as a role of their collision energy. Spectroscopic analysis has been crucial in the development of the most fundamental hypothesis in physics, including quantum mechanics, the special and general theories of relativity, and quantum electrodynamics. Spectroscopy, as applied to high-energy collisions, has been a key tool in developing scientific consideration not only of the electromagnetic force but also of the strong and weak nuclear forces.

The study of chemical reactions, isomerizations and physical behavior that may occur under the influence of visible and/or ultraviolet light is known as Photochemistry. Photochemistry is the underlying mechanism for all of photobiology. When a molecule absorbs a photon of light, its electronic constitution changes, and it reacts differently with other molecules. The energy that is absorbed from light can effect in photochemical changes in the absorbing molecule, or in an adjacent molecule (e.g., photosensitization). The energy can also be set off as heat, or as lower energy light, i.e., fluorescence or phosphorescence, in order to    give back the molecule to its ground state. Each type of molecule has a different preference for which of these different mechanisms it utilizes to get rid of absorbed photon energy, e.g., some prefer fluorescence over chemistry.

The Basic Laws of Photochemistry are,

• The first law of photochemistry, the Grotthuss-Draper law, states that light must be absorbed by a compound in order for a photochemical reaction to occur.
• The second law of photochemistry, the Stark-Einstein law, states that for every photon of light absorbed by a chemical system, only one molecule is activated for subsequent reaction. This "photoequivalence law" was derived by Albert Einstein throughout his development of the quantum (photon) theory of light.

Quantum chemistry is a field of chemistry whose primary focus is the application of quantum mechanics in physical models and experiments of chemical systems. It is also known as molecular quantum mechanics. Quantum chemistry is the application of quantum mechanical theories and equations to the study of molecules. In order to understand matter at its most fundamental measure, we must utilize quantum mechanical models and methods. There are two aspects of quantum mechanics that make it differ from previous models of matter. The first is the concept of wave-particle duality; that is, the notion that we want to think of very small objects (such as electrons) as having characteristics of both particles and waves. Second, quantum mechanical models precisely predict that the energy of atoms and molecules is always quantized, meaning that they may have only certain amounts of energy. Quantum chemical theories allow us to elucidate the structure of the periodic table, and quantum chemical calculations allow us to accurately predict the structures of molecules and the spectroscopic behaviour of atoms and molecules.

Solid-state chemistry, also sometimes mentioned to as materials chemistry, is the study of the synthesis, structure, and properties of solid phase materials, peculiarly, but not necessarily exclusively of, non-molecular solids. Solid-state chemistry continues to play an amplifying role in an astounding array of disciplines. As the discovery of new physical phenomena has often depended on the progression of new materials, the synthesis of new solid-state materials and kinetically solid composites with optimized properties is of central importance. While solid-state materials have historically been developed through high temperature solid-state reactions, generally affording the most thermodynamically stable phases, a variety of techniques have been developed to master the limitations inherent in this traditional approach.

Thermochemistry is the study of the heat liberated or absorbed as a result of chemical reactions. It is a branch of thermodynamics and is used by a wide range of scientists and engineers. Thermochemistry focuses on these energy changes, particularly on the system's energy exchange with its surroundings. For example, biochemists use thermochemistry to understand bioenergetics, whereas chemical engineers apply thermochemistry to depict manufacturing plants. Chemical reactions involve the conversion of a set of substances inclusively referred to as "reactants" to a set of substances collectively referred to as "products."

Biophysical chemistry is a physical science that uses the concepts of physics and physical chemistry for the study of biological systems. The most common feature of the research in this subject is to seek explanation of the various phenomena in biological systems in terms of either the molecules that make up the system or the supra-molecular structure of these systems. Biophysical chemists employ various techniques used in physical chemistry to probe the structure of biological systems. These techniques include spectroscopic methods such as nuclear magnetic resonance (NMR) and X-ray diffraction.

Physical Chemistry of Macromolecules employs the combined principles of physical chemistry to define the behaviour, structure, and intermolecular effects of macromolecules in both solution and bulk states. It emphasizes the statistical measures of structure and weight distribution, and also discusses structural, dynamic, and optical properties of macromolecules in solution.