What are three main ideas in Dalton’s atomic theory?

Atoms are the fundamental building blocks of all matter, according to Dalton's Atomic Theory, a historical concept proposed by John Dalton in the early 19th century.
The theory's perspective on atomic structure details that atoms are indivisible particles that make up elements. These atoms can combine in various ways to form compounds.
In contemporary science, the atomic structure is understood to be more complex, with atoms consisting of a nucleus containing protons and neutrons, surrounded by electrons in shells. The arrangement of these subatomic particles determines the chemical properties of an element. While Dalton's original model asserted atoms were indivisible, modern physics recognizes that they can be split into smaller parts.

John Dalton posited that chemical reactions involve the reorganization of atoms: they can be combined, separated, or rearranged.
Chemical reactions are governed by the principle of conservation of mass, where the total mass of reactants equals the total mass of products. This is a direct reflection of Dalton's idea that atoms are neither created nor destroyed. However, we now understand that atoms do not change their elemental identity during chemical reactions, but rather, they form different compounds by creating or breaking chemical bonds.

Dalton's Atomic Theory is a prime example of how historical scientific theories lay the groundwork for our current understanding of scientific principles.
Dalton's model was revolutionary at its time, providing a systematic explanation for chemical compositions and reactions. It was one of the earliest theories to suggest that matter is composed of discrete units. As science advanced, the theory evolved, incorporating the discovery of subatomic particles and isotopes, which led to the development of modern atomic theory. These historical theories are crucial as they often pave the way for new scientific inquiries and discoveries.

While Dalton's Atomic Theory asserted that atoms of a given element are identical in mass and properties, this was later found to be an incomplete picture due to the discovery of isotopes.
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons, resulting in different atomic masses. This refinement of atomic theory illustrates how scientific understanding is subject to change as new evidence emerges, thus highlighting the dynamic nature of scientific knowledge. Isotopes have important implications in various fields, such as radiometric dating in geology, medical diagnostics, and nuclear energy.