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Which parts of Dalton’s atomic theory were later shown to be incorrect?

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Bohr model diagram of a hydrogen atom showing a green nucleus labeled H, a single electron orbit, and text with atomic mass 1.008 and electron configuration 1. — atom The Bohr model describes the structure of atoms, in this case hydrogen.

While John Dalton’s atomic theory provided a foundational scientific framework for chemistry, several of its core tenets were later proven incorrect by subsequent discoveries in physics and chemistry:

Indivisibility and Indestructibility: Dalton proposed that atoms were indivisible and indestructible, meaning they could not be created, destroyed, or divided into smaller pieces. We now know that atoms are composed of subatomic particles—protons, neutrons, and electrons—and can be split or transformed, as demonstrated by radioactivity and nuclear processes.12
Identical Atoms: Dalton stated that all atoms of a specific element are identical in shape, size, and mass. The discovery of isotopes proved this false, as atoms of the same element can have different numbers of neutrons and, consequently, different atomic masses.13
Immutability: Dalton believed atoms could not be transformed into other elements. Modern science has shown that atoms can undergo transmutation, particularly through radioactive decay and nuclear reactions.124