In order for a chemical equation to be properly balanced, which of the following must be true?

• A. The number of atoms of each element is the same on both sides of the equation.
• B. The sum of the coefficients on the reactant side equals the sum on the product side.
• C. The charges of all ions must be zero on both sides of the equation.
• D. The total number of molecules is the same on both sides of the equation.

Answer: (A)

Verified step by step guidance

1. Understand that a balanced chemical equation must obey the Law of Conservation of Mass, which states that matter cannot be created or destroyed in a chemical reaction.
2. Recognize that this means the number of atoms of each element must be the same on both the reactant and product sides of the equation.
3. Note that the sum of the coefficients on each side does not necessarily have to be equal, as coefficients represent the relative number of molecules or moles, not atoms.
4. Understand that charges do not have to be zero on both sides unless the reaction involves ions; however, the total charge must be balanced in ionic equations.
5. Realize that the total number of molecules can differ because molecules can combine or break apart, but the elemental atoms must remain balanced.