The first scientific experiment that indicated the existence of atoms was performed by John Dalton during the 1800s. These early experiments did not yield information regarding the atom's structure. The structure of atom... More »

Greek rationalism deals with trying to understand the world using logic and observation. While non-Greek contemporaries had similar ideas, Greek philosophy formed the basis for Western rationalism. Greek rationalist phil... More »

Scientists can confirm the existence of atoms using a technique called scanning tunneling microscopy. This is a procedure in which extremely sensitive equipment disturbs a sample at a microscopic level and detects the ch... More »

Although the early Greek philosopher Democritus hypothesized the existence of atoms, it was not until the late 1800s that English physician J.J. Thomson proposed a model for the atom. J.J. Thomson discovered the atom bec... More »

The solid sphere model proposed by John Dalton stated that atoms consisted of negative charges embedded in a solid continuum of positive charge. The magnitude of the embedded negative charge would cancel the positive cha... More »

John Dalton's theory regarding atomic theory, published in 1808, incorrectly stated that atoms were the indivisible components of matter. This was later shown to be incorrect when the existence of electrons, protons and ... More »

The atomic theory formulated by the British chemist John Dalton proposes that atoms are indivisible particles comprising all matter; atoms of the same element share identical properties, including shape, size and mass; a... More »