What is the primary focus of the atomic theory as proposed by Dalton?

The atomic theory proposed by John Dalton fundamentally established that all matter is composed of tiny, indivisible particles known as atoms. This idea suggests that atoms serve as the essential building blocks that combine in various ways to form all substances. Dalton's theory was pivotal in advancing the understanding of matter’s composition, providing a coherent framework that emphasized the role of atoms in chemical reactions and the formation of compounds.

This foundational concept underlies much of modern chemistry, illustrating that different arrangements and combinations of atoms lead to the diversity of substances we observe. Dalton also recognized that atoms of different elements exhibit distinct properties, further supporting the idea that these tiny particles are the core constituents of matter.

While the other options bring up important concepts in chemistry, they do not capture the essence of Dalton's contribution as directly as the notion that atoms are the building blocks of matter. For instance, the formulation of compounds from elements is indeed part of the atomic theory but stems from the broader idea that atoms themselves are the fundamental units.