What is a chemical reaction?

A chemical reaction is when one atom splits apart with another one.

A chemical reaction is characterized by the re-arrangement of atoms from the reactant side of the equation to the product side. It's a bit like square dancing because at any given time you may have a different partner than when you started but no matter how you re-arrange the dancers, you always have the same people.

Some examples:

  • Hydrogen gas burns in oxygen to make water:
2H2 + O2 --> 2H2O
  • Aqueous lead (II) nitrate reacts with aqueous sodium chloride to produce solid lead (II) chloride and aqueous sodium nitrate:
Pb(NO3)2(aq) + 2NaCl(aq) --> PbCl2(s) + 2NaNO3(aq)

...in any chemical reaction, nothing is lost, just re-arranged.

A process in which one or more substances (reactants) are chemically changed into one or more newsubstances (products). Chemical changes may involve motion of electrons in the forming and breaking of chemical bonds.
The breaking of older bonds and formation of new bonds is a chemical reaction.

A chemical reaction involve the transformation of reactants molecules in products .

A chemical reaction is a process in which two or more substances react together chemically to form new products. It involves breaking one or more bonds in the reactants and forming new bonds in the products. A chemical equation is used to illustrate a chemical reaction, with reactants on the left and products on the right hand side.