or no valency at all. No atomic model, so far as I know, has succeeded in making this difference plausible; but it is not essential to the hypothesis, that, independently of any atomic model:—(i ...

In ancient Greece, most people thought that matter was made up of combinations of four elements: earth, air, fire and water. There were a small number of Greeks who had a different idea. They ...

He concluded that all matter was made of tiny particles called atoms. He suggested that an atom was a tiny solid ball. He published his ideas in 1803. This atomic model has changed over time.

All of these systems are made up of dissimilar materials that, where they join at the atomic scale, display very different behaviour from what might be expected of the bulk materials. Advances in ...