No atoms are created or destroyed in a chemical reaction – they are just rearranged.
Balanced symbol equations show the original arrangements and the new ones.
|Check to see if there is an equal number of atoms of each element on both sides. There is not.||N2 + H2 → NH3|
|There are two nitrogen atoms on the left but only one on the right, so put a big 2 on the left of the NH3.||N2 + H2 → 2NH3|
|Check again. There are two hydrogen atoms on the left but (2 × 3) = 6 on the right, so put a big 3 in front of the H2.||N2 + 3H2 → 2NH3|
|Check again to see if there are equal numbers of each element on both sides. There is.||(Two nitrogen atoms and six hydrogen atoms)|
|Add the state symbols if asked to do so.||N2(g) + 3H2(g) → 2NH3(g)|