A chemical reaction occurs that involves combining the following reactants:

4 atoms of nitrogen, 8 atoms of oxygen, 2 atoms of hydrogen

After the reaction, how many atoms of each element will there be in the product?

Chemical reaction, a process in which one or more substances, the reactants, are converted to one or more different substances, the products. Substances are either chemical elements or compounds. A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products.