Element and Radical: the Divergence of Synonyms

The nouns “element” and “radical” are prominent words in the chemist’s vocabulary. That their meanings nowadays are radically different is a fact that is elementary to all, yet, given their prominence, it is striking that a millennium ago they were virtually synonyms. By the late eighteenth century, Lavoisier and his colleagues had assigned them different denotations. Given the fundamental status of these two words in modern chemistry, it seems of interest to sketch the synonyms’ divergent histories, which are taken in this paper through the first decades of the nineteenth century. Inevitably, the evolution of words is about the evolution of ideas. In this case, it is the evolving complexity of our ideas about the fundamental nature of matter that acts as a wedge to drive their meanings apart.