What happened to daltons theory in the late 1800s?

In the late 1800s, Dalton's atomic theory underwent significant revisions due to advancements in scientific understanding. The discovery of subatomic particles, such as electrons by J.J. Thomson in 1897, challenged the notion of indivisible atoms. Additionally, the development of the Periodic Table and insights into chemical bonding revealed that atoms of the same element could exist in different isotopes, contradicting Dalton's assertion that all atoms of an element are identical. These developments led to a more nuanced understanding of atomic structure and behavior.