Atomic Foundations of Matter Mind Map

The law of conservation of mass states that during a chemical change, the total mass of reactants is equal to the total mass of products.

When a question gives masses before and after a reaction, add all reactant masses and all product masses before comparing.

The law of constant proportions states that a pure chemical compound always contains the same elements combined in the same fixed ratio by mass.

For mass-ratio questions, reduce the given masses to the simplest ratio and check whether the ratio is constant.