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430 BCE
Democritus
Democritus was a central figure in the development of the atomic theory of the universe. He theorized that all material bodies are made up of indivisibly small “atoms.” 5th century. Aristotle refused to believe that the whole of reality is reducible to a system of atoms, as Democritus said. As it turned out, though, Democritus was right. Democritus was born c. 460 BCE—died c. 370. -
384 BCE
Aristotle
Aristotle's ideas were not contradicted by anyone until the 17th century. He greatly slowed down the evolution of the atomic theory by saying it didn't exist in 384 BC. He was a philosopher, not a scientist. He also believed that everything was a combination of the four elements: earth, fire, water, air. His theory was that a mass of incomprehensible size was everywhere. There was no separate 'particles' for each material, it was all one. -
Billiard Ball Model
John Dalton thought atoms were the smallest particles of matter, he envisioned them as solid, hard spheres, like billiard (pool) balls, so he used wooden balls to model them. -
JJ Thomson
Joseph John Thomson was born in Cheetham Hill, Manchester on December 18, 1856. On his return from America, he achieved the most brilliant work of his life an original study of cathode rays culminating in the discovery of the electron. Thomson’s early interest in atomic structure was reflected in his Treatise on the Motion of Vortex Rings which won him the Adams Prize in 1884 -
James Chadwick
James Chadwick played a vital role in the atomic theory, as he discovered the Neutron in atoms. Neutrons are located in the center of an atom, in the nucleus along with the protons. They have neither a positive nor negative charge, but contribute the the atomic weight with the same effect as a proton. Chadwick discovered this subatomic particle by using a neutron chamber in his experiments. Lived in Manchester, England. -
Marie Curie
Marie Curie, née Maria Sklodowska, was born in Warsaw on November 7, 1867. Marie Curie researched and analysed the isolation of polonium and radium. In 1896 Curie developed methods for the separation of radium from radioactive residues in sufficient quantities to allow for its characterization and the careful study of its properties, therapeutic properties in particular. -
Toroidal ring model
In 1897, the English physicist J.J. Thomson discovered the electron and proposed a model for the structure of the atom. Thomson knew that electrons had a negative charge and thought that matter must have a positive charge. His model looked like raisins stuck on the surface of a lump of pudding. Rutherford thought that the negative electrons orbited a positive center in a manner like the solar system where the planets orbit the sun. -
John Dalton
The theory of atomism, proposed by Dalton in the early 19th century and derived from meteorological studies, is the foundation for our modern concept of the atom. Although a schoolteacher, a meteorologist, and an expert on color blindness, John Dalton is best known for his pioneering theory of atomism. He also developed methods to calculate atomic weights and structures and formulated the law of partial pressures. Dalton (1766–1844) lived in Cumberland, England -
Plum Pudding Model
The atomic structure proposed by J.J. Thomson in the late 19th century. Thomson had discovered that atoms are composite objects, made of pieces with positive and negative charge, and that the negatively charged electrons within the atom were very small compared to the entire atom. -
Albert Einstein
Albert Einstein was born at Ulm, in Württemberg, Germany, on March 14, 1879 In 1908 He dealt with classical problems of statistical mechanics and problems in which they were merged with quantum theory: this led to an explanation of the Brownian movement of molecules. He investigated the thermal properties of light with a low radiation density and his observations laid the foundation of the photon theory of light. -
Nuclear Model
Ernest Rutherford atomic model.The model described the atom as a tiny, dense, positively charged core called a nucleus, in which nearly all the mass is concentrated, around which the light, negative constituents, called electrons, circulate at some distance, much like planets revolving around the Sun. -
Bohr Model
Niels Bohr proposed the Bohr Model of the Atom in 1913.The Bohr Model is a planetary model in which the negatively-charged electrons orbit a small, positively-charged nucleus similar to the planets orbiting the Sun (except that the orbits are not planar) -
Ernest Rutherford
Ernest Rutherford was born on August 30, 1871, in Nelson, New Zealand. Rutherford researched in New Zealand 1919, where he worked with the magnetic properties of iron exposed to high-frequency oscillations, and his thesis was entitled Magnetization of Iron by High-Frequency Discharges.At the Cavendish Laboratory, he invented a detector for electromagnetic waves, an essential feature being an ingenious magnetizing coil containing tiny bundles of magnetized iron wire. -
Wave Model
Erwin Schrödinger combined the equations for the behavior of waves with the de Broglie equation to generate a mathematical model for the distribution of electrons in an atom.In historical linguistics, the wave model or wave theory (German Wellentheorie) is a model of language change in which a new language feature (innovation) or a new combination of language features spreads from its region of origin, affecting a gradually expanding cluster of dialects -
Quantum Model
In 1926 Erwin Schrödinger, an Austrian physicist, took the Bohr atom model one step further. Schrödinger used mathematical equations to describe the likelihood of finding an electron in a certain position. This atomic model is known as the quantum mechanical model of the atom. -
Niels Bohr
Niels Henrik David Bohr was born in Copenhagen on October 7, 1885. Bohr’s activities in his Institute were since 1930 more and more directed to research on the constitution of the atomic nuclei, and of their transmutations and disintegrations.He studied the structure of atoms on the basis of Rutherford’s discovery of the atomic nucleus. -
Werner Heisenberg
Werner Heisenberg was born on 5th December, 1901, at Würzburg.Heisenberg’s name will be associated with his theory of quantum mechanics, published in 1925 this theory and the applications resulted in the discovery of allotropic forms of hydrogen Heisenberg was awarded the Nobel Prize for Physics for 1932. -
Lucas Model
The Bergman elementary particle model and Lucas atomic model state that subatomic particles are rings, rather than spheres, point particles, or wave functions. The rings have a charge that circuits the ring at the speed of light which sets up a magnetic field. The rings are stationary, some electrons are external to the nucleus but do not orbit it, there is no wave function located around the atom.
