n+h→nh3
we must remember that nitrogen and hydrogen are both diatomic molecules in their standard gas form. this adjusts the equation to
n2+h2→nh3
now we need to adjust coefficients in order to balance the atoms on each side of the equation. currently we have 2 atoms of nitrogen and 2 atoms of hydrogen on the reactant side and 1 atom of nitrogen and 3 atoms of hydrogen on the product side.
we can balance the hydrogens by placing a coefficient of 2 in front of ammonia and a coefficient of 3 in front of the hydrogen.
n2+3h2→2nh3
this gives us 6 hydrogen on each side and coincidentally the nitrogens now equal 2 on each side.