Final answer:
The law of conservation of mass states that during a chemical reaction, the number of atoms and the mass remain unchanged even though the appearance of substances may alter. This principle ensures the total atomic mass of reactants is equal to the mass of products, affirming matter cannot be created nor destroyed.
Step-by-step explanation:
According to the law of conservation of mass, in a chemical reaction, matter is neither created nor destroyed. This means that the number of atoms of each element, and by extension the mass, remains constant throughout the reaction. Therefore, Keesha observed that although the products might look different from the reactants, the amount of matter remained the same, as demonstrated by the unchanged total mass before and after the reaction. This is a fundamental concept in stoichiometry, which is the measurement of elements within chemical reactions.
For example, if you start with four hydrogen atoms and one carbon atom as reactants, you must end up with four hydrogen atoms and one carbon atom in the products, regardless of how they are rearranged. Thus, the total atomic mass of reactants equals the total atomic mass of the products. In sum, chemical reactions involve rearrangement of atoms, not their creation or annihilation.