The recent availability of high-speed supercomputers to solve the Schrödinger equation has made possible accurate calculations of properties for atoms and molecules with ever larger numbers of electrons. To the extent that the Schrödinger equation can be solved for more-complex cases, atomic theory is capable of predicting from first principles the properties of all atoms and their interactions. The equation can be solved exactly for an atom containing only a single electron ( hydrogen), and very close approximations can be found for atoms containing two or three electrons ( helium and lithium, respectively). Austrian physicist Erwin Schrödinger devised a partial differential equation for the quantum dynamics of atomic electrons, including the electrostatic repulsion of all the negatively charged electrons from each other and their attraction to the positively charged nucleus. With the advent of quantum mechanics and the Schrödinger equation in the 1920s, atomic theory became a precise mathematical science. The experiments of the British physicist Ernest Rutherford in the early 20th century on the scattering of alpha particles from a thin gold foil established the Rutherford atomic model of an atom as consisting of a central, positively charged nucleus containing nearly all the mass and surrounded by a cloud of negatively charged planetlike electrons. The modern atomic theory, which has undergone continuous refinement, began to flourish at the beginning of the 19th century with the work of the English chemist John Dalton. The ancient atomic theory was proposed in the 5th century bce by the Greek philosophers Leucippus and Democritus and was revived in the 1st century bce by the Roman philosopher and poet Lucretius. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!Ītomic theory, ancient philosophical speculation that all things can be accounted for by innumerable combinations of hard, small, indivisible particles (called atoms) of various sizes but of the same basic material or the modern scientific theory of matter according to which the chemical elements that combine to form the great variety of substances consist themselves of aggregations of similar subunits (atoms) possessing nuclear and electron substructure characteristic of each element.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians. ARISTOTLE ATOMIC THEORY HOW TOCOVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today.Student Portal Britannica is the ultimate student resource for key school subjects like history, government, literature, and more.This Time in History In these videos, find out what happened this month (or any month!) in history.#WTFact Videos In #WTFact Britannica shares some of the most bizarre facts we can find.Demystified Videos In Demystified, Britannica has all the answers to your burning questions.Britannica Explains In these videos, Britannica explains a variety of topics and answers frequently asked questions.Britannica Classics Check out these retro videos from Encyclopedia Britannica’s archives.
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