Which scientist proposed atomic theory?

Which scientist proposed atomic theory?

• A. John Dalton
• B. Empedocles
• C. Democitus
• D. J.J Thomson

Answer: (A)

The idea being tested is who first built a cohesive model that matter is made of small, indivisible units called atoms and that these units explain how substances combine and react. John Dalton did this in the early 1800s by proposing the first modern atomic theory. He stated that all matter is composed of atoms, that atoms of a given element are identical in their properties, that compounds form when atoms combine in simple whole-number ratios, and that chemical reactions are rearrangements of atoms. This framework tied together observations about why elements combine in fixed proportions and how reactions alter substances without creating or destroying atoms. Earlier thinkers like Democritus had speculative ideas about indivisible particles without experimental support, and Empedocles proposed four elements rather than atoms. J.J. Thomson later identified the electron and helped refine atomic structure, but the origin of the atomic theory as a testable idea goes to Dalton.

The idea being tested is who first built a cohesive model that matter is made of small, indivisible units called atoms and that these units explain how substances combine and react. John Dalton did this in the early 1800s by proposing the first modern atomic theory. He stated that all matter is composed of atoms, that atoms of a given element are identical in their properties, that compounds form when atoms combine in simple whole-number ratios, and that chemical reactions are rearrangements of atoms. This framework tied together observations about why elements combine in fixed proportions and how reactions alter substances without creating or destroying atoms. Earlier thinkers like Democritus had speculative ideas about indivisible particles without experimental support, and Empedocles proposed four elements rather than atoms. J.J. Thomson later identified the electron and helped refine atomic structure, but the origin of the atomic theory as a testable idea goes to Dalton.