Final answer:
Democritus's early ideas about atoms being indivisible and having different shapes, sizes, and masses were intuitive, but not based on experimentation. John Dalton's theory further developed the concept of atoms with experimental support, focusing on the physicality and permanence of atoms. However, some aspects of both theories have been revised or disproven with modern scientific knowledge.
Step-by-step explanation:
Democritus and John Dalton both contributed foundational ideas to our understanding of atomic theory, with some distinctions between their proposals. Democritus is credited with the concept that matter is composed of indivisible particles called 'atomos.' Nevertheless, his theory lacked experimental evidence and was philosophical rather than scientific. His assertion that atoms had different shapes, sizes, and masses but other characteristics like color and taste were merely due to atomos combinations was intuitive but lacked the support of practical inquiry.
In contrast, John Dalton's atomic theory, developed in the 19th century, emphasized logical thinking and experimentation. Dalton suggested that atoms of different elements are distinct in all respects and introduced the concept that compounds are combinations of atoms of different elements in defined proportions. He believed atoms could not be created or destroyed, emphasizing atoms'physicality and permanence which aligned somewhat with Democritus's early ideas.
While Dalton's work advanced and gave credibility to the atomic theory, some aspects have since been disproven. One example is the discovery that atoms of different elements can have the same atomic masses, as seen with argon and calcium both having an atomic mass of 40 amu. Another aspect of Dalton's theory that has been revised is that atoms are indeed divisible into smaller particles, such as protons, neutrons, and electrons.