Chemical reactions

A chemical reaction takes place ,when ever bonds between atoms are broken or made.In each case, atoms or groups of atoms rearrange,making new substance s(products)from the orginal ones (Reactants).Reaction happen naturally,or can be made to happen;they may take years ,or only an instant.Some of main types are shown here.A eaction usually involve a change in energy.in a burning reaction,for example,the making of new bonds between atoms releases energy as heat and light.This type of reaction ,in which heat is given off,is exothermic reaction.Many reaction like burning ,are inversible.Reactions can be used to form solids from sollution:in a double decomposition reaction, two compounds in sollution break down and re-form into two new substances,often create a precipitate (insoluble solid);in displacement,an element(eg:copper) displaces another element (eg.silver)from a sollution.The rate of (speed) of a reaction is determined by many different factors,such as temperature,and the size and shape of the reactants.to describe and keep track of reactions,internationally recogonized chemical symbols and equations are used.Reactions are also used in the laboratary to identify matter.An experiment with candle wax,for example,demonstrates that it contains carbon and hydrogen.