Then, move on to the atom that shows up the second least number of times, and so on. It is best to start with the atom that shows up the least number of times on one side, and balance that first. We can break the house apart and build an airplane, but the color and shape of the actual blocks do not change.īut how do we go about balancing these equations? We know that the number of atoms of each element needs to be the same on both sides of the equation, so it is just a matter of finding the correct coefficients (numbers in front of each molecule) to make that happen. An easy way to understand this is to picture a house made of blocks. This means that chemical reactions do not change the actual building blocks of matter rather, they just change the arrangement of the blocks. So, if we start with ten atoms of oxygen before a reaction, we need to end up with ten atoms of oxygen after a reaction. This stems from the universal law of the conservation of mass, which states that matter can neither be created nor destroyed. The ultimate goal for balancing chemical equations is to make both sides of the reaction, the reactants and the products, equal in the number of atoms per element.