Nov 14, 2025 · However, atoms are made up of three types of subatomic particles: the heavy protons and neutrons that make up the nucleus (the central part of the atom), and the much lighter electrons …

Democritus devoted considerable attention to perception and knowledge. He asserted, for example, that sensations are changes produced in the soul by atoms emitted from other objects that impinge on it; …

The tiny particles called atoms are the basic building blocks of all matter. Atoms can be combined with other atoms to form molecules, but they cannot be divided into smaller parts by ordinary means.

Atoms are made up of three basic types of particle: protons, neutrons, and electrons. These particles (as well as other particles smaller than atoms) are known as subatomic particles.

Learn about the discovery of atoms and the instruments scientists use to see these small particles.

It attempts to describe and account for the properties of molecules and atoms and their constituents— electrons, protons, neutrons, and other more esoteric particles such as quarks and gluons.

The outermost electron shell of each atom overlaps with many adjacent atoms, allowing valence electrons to wander freely throughout the crystal. This accounts for many characteristic properties of …

For a detailed discussion of the structure and properties of atoms, see atom. Chemical compounds are surveyed in the article chemical compound, and the elements are described in the article chemical …

Nov 28, 2025 · John Dalton, English meteorologist and chemist, a pioneer in the development of modern atomic theory. His theory was notable for, among other things, positing that each element had its …

Nov 14, 2025 · Dalton had begun his atomic studies by wondering why the different gases in the atmosphere do not separate, with the heaviest on the bottom and the lightest on the top. He decided …