What part of Dalton's theory has been disproved?

Parts of Daltons theory have been disproved, such as the idea that every atom within a given element is identical, for now we know of isotopes. Isotopes are each of two or more forms of the same element that contain the same number of protons but a different number of neurtons within their nuclei. read more

Setting aside that Dalton's theory is still, in part, accepted, the portions of the theory that have been disproved are: All atoms are identical: Since different isotopes of different atoms occur, that is not entirely accurate. read more

Atomic Theory. In 1897, English physicist J. J. Thomson (1856–1940) disproved Dalton's idea that atoms are indivisible. When elements were excited by an electrical current, atoms break down into two parts. One of those parts is a negative tiny particle, which Thomson called a corpuscle in 1881. read more

A All elements are composed of atoms. B Atoms are indivisible particles. C Atoms of different elements are different. D Compounds are composed of two or more elements. read more