QUARK UNIVERSITY

Subatomic particles are particles that are smaller than an atom. In 1940, the number of subatomic particles known to science could be counted on the fingers of one hand: protons, neutrons, electrons, neutrinos, and positrons. The first three particles were known to be the building blocks from which atoms are made: protons and neutrons in atomic nuclei and electrons in orbit around those nuclei. Neutrinos and positrons were somewhat peculiar particles discovered outside Earth ‘s atmosphere and of uncertain origin or significance. That view of matter changed dramatically over the next two decades. With the invention of particle accelerators (atom-smashers) and the discovery of nuclear fission and fusion, the number of known subatomic particles increased. Scientists discovered a number of particles that exist at energies higher than those normally observed in our everyday lives: sigma particles, lambda particles, delta particles, epsilon particles, and other particles in positive, negati...

ATOMS (A short history of the knowledge of the atom) Compiled by Indrajit Banerjee Originated: Sept. 2016 Latest revision: june. 2017   atom  n. A unit of matter, the smallest unit of an element, consisting of a dense, central, positively charged nucleus surrounded by a system of electrons, equal in number to the number of nuclear protons, the entire structure having an approximate diameter of 10-8 centimeter and characteristically remaining undivided in chemical reactions except for limited removal, transfer, or exchange of certain electrons. The history of the study of the atomic nature of matter illustrates the thinking process that goes on in the philosophers and scientists heads. The models they use do not provide an absolute understanding of the atom but only a way of abstracting so that they can make useful predictions about them. The epistemological methods that scientists use provide us with the best known way of arriving at useful science and factual knowle...