Reactions which can be explained on the basis of gain or loss of electrons is called redox reactions.
In molecular compounds, the combining capacity i.e. the valency of each combining element determines the chemical formula of the compound.
The valency of an electropositive ion and an electronegative ion is equal to the positive or negative charge on it.
Reactants are substances that take part in a chemical reaction, while products are the new substances produced during the chemical reaction.
When two or more elements or compounds react chemically to form one new compound, then the chemical reaction that takes place is a chemical combination reaction.
When a chemical compound decomposes on heating or by some other way so as to form two or more compounds or elements then the reaction that takes place is called chemical decomposition.
When a more active metal or nonmetal displaces a less active element from its aqueous salt solution, the reaction that takes place is called displacement or substitution reaction.
A chemical reaction in which two ionic compounds in their aqueous solutions react by exchanging their ions/radicals to form to two new compounds is called chemical double decomposition.
A polymerization reaction is one in which two or more molecules (monomers) combine to form a new bigger molecule.
Chemical equations can be made more informative by indicating physical states, heat changes and condition under which the reaction takes place.
A reaction in which heat is given out is exothermic. DH is negative
A reaction in which heat is taken in is called endothermic. DH is positive.
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