A chemical equation describes what is occuring in a chemical reaction and is made up of two parts, the reactants and the products. To create a chemical equation you need to know what is going into the reaction as that will determine what, and how much, is going to be produced. Sometimes you can combine things together many different ways and produce many different things (Hydrocarbons are a perfect example), so it is also a good idea to know the end result of the reaction too.
Take Hydrogen gas (H2) and Oxygen gas (O2), If you react these together you will make water,
H2 + O2 --> H2O
But there is a catch, water has twice as many Hydrogen atoms in it per molecule as it does Oxygen, so it should require twice as much Hydrogen gas as Oxygen gas. To balance this equation, we put coefficients infront of certain substances,
2H2 + O2 --> 2H2O, this was there are 4 Hydorgen atoms and 2 Oxygen atoms on each side.
chemical equation is an expression representing a chemical reaction; the formulas of the reactants (on the left) are connected by an arrow w/ the formulas for the products (on the right).
reactants-------> products (this is the structure of a chemical equation)
Fe + O2-----> Fe2O3
Fe (iron) has an oxidation # of 3 & O2 (oxygen) has an oxidation # of 2... you just have to exchange them in places... but not in a superscript form... put them in the bottom (subscript) of the symbol of the element...
there are also polyatomic ions that if you're going to make them as a chemical equation, it's more complex.... just type chemical equation in the google & you can understand better on what i've said... good luck.....