coefficient
There are 3 major parts for each reactant in a formula. That would be the coefficient, subscript, and element. For instance, the burning of methane (CH4) in oxygen. The unbalanced formula is
CH4 + O2 => CO2 + H2O
The numbers 2 and 4 above should all be subscripts, but I'm limited in my ability to type them. And the letters each represent elements. If you carefully count the number of atoms for each element, you'll soon determine that they don't match. For instance, the left side has 1 carbon, 4 hydrogen, and 2 oxygen. Bu the right side has 1 carbon, 2 hydrogen and 3 oxygen. To balance the equation, we need to add coefficients to the equation so that the number of atoms for each element matches. The balanced formula, created by adding coefficients is
CH4 + 2 O2 => CO2 + 2 H2O
Which now has 1 carbon, 4 hydrogen, and 4 oxygen on both sides.
