# data[].attributes.body
According to the Bohr model, often referred to as a planetary model, the electrons encircle the nucleus of the atom in specific allowable paths called orbits. When the electron is in one of these orbits, its energy is fixed.

# data[].attributes.body
On April 30, 1897, British physicist J.J. Thomson announced his discovery that atoms were made up of smaller components. This finding revolutionized the way scientists thought about the atom and had major ramifications for the field of physics.

# data[].attributes.body
Dalton's Atomic Theory (1804)

All matter is composed of extremely small particles called atoms. Atoms of a given element are identical in size, mass, and other properties. Atoms of different elements differ in size, mass, and other properties. Atoms cannot be subdivided, created, or destroyed.

# data[].attributes.body
The Rutherford atomic model was also known as the "Rutherford nuclear atom" and the "Rutherford Planetary Model". In 1911, Rutherford described the atom as having a tiny, dense, and positively charged core called the nucleus. Rutherford established that the mass of the atom is concentrated in its nucleus.

# data[].attributes.body
is the scientific theory that matter is composed of particles called atoms. Atomic theory traces its origins to an ancient philosophical tradition known as atomism. According to this idea, if one were to take a lump of matter and cut it into ever smaller pieces, one would eventually reach a point where the pieces could not be further cut into anything smaller. Ancient Greek philosophers called these hypothetical ultimate particles of matter atomos, a word which meant "uncut".

# data[].attributes.body
An atom is a complex arrangement of negatively charged electrons arranged in defined shells about a positively charged nucleus. This nucleus contains most of the atom's mass and is composed of protons and neutrons (except for common hydrogen which has only one proton). All atoms are roughly the same size.

# data[].attributes.body
https://www.compoundchem.com/2016/10/13/atomicmodels/
https://www.britannica.com/science/atomic-theory

# data[].attributes.attachment_link.readable_text
Table of Contents

This article was most recently revised and updated by

atomic 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. 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. 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 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.

With the advent of quantum mechanics and the Schrödinger equation in the 1920s, atomic theory became a precise mathematical science. 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. 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). 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 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. Precise agreement with experiment is obtained if small corrections due to the effects of the theory of special relativity and quantum electrodynamics are also included.

Who was the first scientist to conduct a controlled nuclear chain reaction experiment? What is the unit of measure for cycles per second? Test your physics acumen with this quiz.

The Editors of Encyclopaedia Britannica Erik Gregersen.

# data[].attributes.attachment_link.title
atomic theory | Definition, Scientists, History, & Facts

# data[].attributes.attachment_link.description
atomic 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.

# data[].attributes.attachment_link.title
Bohr's Model of an Atom - Class 9 Tutorial