Which statements are consistent with Dalton's atomic theory as it was originally stated? Why? a. Sulfur and oxygen atoms have the same mass. b. All cobalt atoms are identical. c. Potassium and chlorine atoms combine in a 1: 1 ratio to form potassium chloride. d. Lead atoms can be converted into gold.

In the context of Dalton's atomic theory, atomic mass is a fundamental concept signifying the weight of individual atoms. Dalton postulated that atoms of each element possess a distinct atomic mass, which is why the idea that sulfur and oxygen atoms have the same mass was immediately recognized as incorrect. According to Dalton, the atomic mass of an element is consistent across all its atoms, thus supporting the notion that all cobalt atoms are identical in mass.

Understanding atomic mass is crucial for students, as it underpins the quantitative aspects of chemical reactions and stoichiometry—the calculation of reactants and products in chemical processes. In the example of potassium and chlorine combining to form potassium chloride, the ratio of their combination relies on their individual atomic masses to ensure a correct chemical formulation.

Delving into chemical compounds brings us to another core facet of Dalton's atomic theory. This theory conceives compounds as the result of atoms from different elements binding together in fixed, simple numeric ratios. For instance, potassium and chlorine atoms combine in a 1:1 ratio to form the compound potassium chloride. This simple ratio aligns perfectly with Dalton's theory and illustrates the specific manner in which elements react to form compounds.

It is essential for learners to grasp that the theory views chemical reactions as the rearrangement of atoms to produce new substances. The set ratios in which atoms combine are determined by their atomic masses and their valency, or combining capacity. This concept also teaches students about the conservation of mass during chemical reactions, as Dalton's theory proposes that the total mass of reactants equals the total mass of products.

The notion of atomic indivisibility is a keystone of Dalton's atomic theory. It states that atoms are the smallest unit of an element and cannot be created, divided, or destroyed in chemical processes. This fundamental principle is exemplified in the exercise by refuting the possibility of converting lead atoms into gold atoms. The theory's indivisibility aspect suggests that the transformation of one type of atom into another is not possible through chemical means, a view that, while challenged by modern nuclear physics, was relevant for explaining chemical reactions at Dalton's time.

Students should acknowledge that Dalton's concept of indivisibility was foundational for developing the law of conservation of mass and the understanding of chemical reactions being rearrangements of indestructible atoms to form new substances. While we now know that atoms can be split or transformed in nuclear reactions, Dalton's indivisibility remains significant for explaining basic chemical reactions.