Chem reations, short for chemical reactions is the step by step process that results to the transformation of one set of chemical substances to another. These reaction methods are studied by chemists all over the world. Chem reactions can either be a spontaneous reaction which requires no input of energy in order for the reaction to take place. The other type of chem reaction is called a nonspontaneous requires some sort of input energy in order for the reaction to take place. They usually use heat, light or electricity as their source of energy. Typically, chem reactions entail changes that strictly involve the motion of electrons in the creation and breakdown of chemical bonds. The basic concept of chem reactions can be applied to transformations of elementary particles, as well as nuclear reactions.

Chem reactions take place between one or more substances which are called reactants. Al chemical reactions are generally classified according to their chemical change that they exhibit and the different products that they yield. These products that are produced usually do not have the same chemical properties as do their reactants. Reactants or reagents are substances or compounds that are consumed in the process of a chem reaction. Catalysts and solvents are not typically referred to as reactants.

There are different chem reactions that are done in combination with chemical synthesis in order to produce the proper and sought after product. In the biochemistry area, a series of chem reactions are catalyzed by enzymes to form metabolic pathways. Decompositions and syntheses are normally impossible in conditions within the cell are performed.

A wide range of chem reactions and approaches to their study ends up in the existence of many concurring and most often, overlapping ways of classifying them. Some examples of these are; isomeriation is where a chemicals structure is rearranged without its net atomic composition being affected. Synthesis of direct combination is where two or more=re chemical elements or compounds join to create a more complex product (N2 + 3 H2 → 2 NH3). Analysis or chemical decomposition is where by a compound is decomposed into far more smaller elements or compounds. Arrhenius definition is the  acids dissociate in water releasing H3O ions disassociate in water which causes the release of OH ions. Double displacement or methathesis is where two compounds exchange ions or bonds to create a unique compound.

Redox chem reations is where the changes in oxidation numbers of atoms in involved species take place. These can often be noted when transferences of electrons between different molecule sites of species. Combustion chem reactions is a form of a redox reaction by which any combustible substance mixes with the oxidizing element which is usually oxygen. This produces the necessary in order to produce an oxidized product. Organic chem reactions entail a very braid range of reactions that involve compounds that contain carbon as the main element in the molecular structure. These types of reactions that involve an organic compound are defined by their functional groups.