How do i balance chemistry equations?

Let's start with Na^+ + Cl^- --> NaCl

If you look at the Na, and the Cl, you should take into account the invisible number beside them.

1 Na + 1 Cl --> 1 NaCl

note that 1 NaCl means there is 1 Na and 1 Cl

So if you look at both sides, there is 1 Na and 1 Cl on the left, and 1 Na and 1 Cl on the right-- which means it's already balanced

But let's look at this equation

N2 + H2 --> NH3

How many Ns are there on the left? 2 N

How many Hs are there on the left? 2 H

How many Ns are there on the right? 1 N

How many Hs are there on the right? 3 H

so it is not balanced

to make it balanced, we can only add numbers BESIDE the LEFT compounds...

Like this: N2 + 3H2 --> 2NH3

Now look at the left, how many Ns do we have? 2 Ns

Look at the left, how many Hs do we have? 3*2= 6 Hs

Look at the right how many Ns do we have? 2 Ns

Look at the right how many Hs do we have? 2*3= 6 Hs

so as you can see, on the left, our Ns are equal, and on the right our Hs are equal and it is balanced!