Antoine Laurent Lavoisier is credited with establishing the first experimentally useful definition of an element.
Lavoisier's Definition of an Element
Lavoisier, a French chemist (1743-1794), defined an element as:
A basic form of matter that cannot be broken down into simpler substances by chemical reactions.
This definition, established by Antoine Laurent Lavoisier, was a major step forward in chemistry because it provided a practical way to identify elements based on experimental results. Instead of relying on philosophical or alchemical ideas, chemists could now determine whether a substance was an element by trying to decompose it through chemical means. If it could not be broken down further, it was considered an element.
