Atomic Theory!

By Noy Inthisone

Democritus

460 BC in Abdera, Thrace to 370 BC

Primarily remembered for his formulation of an atomic theory of the universe.

Everything is composed of atoms, which are physically, but not geometrically, indivisible; that between atom, there lies empty space; that atoms are indestructible; have always been, and will always be, in motion; that there are an infinite number of atoms, and kinds of atoms, which differ in shape and size.

Used sense experiments, I.E. Salt, because of the taste concluded that the atoms are sharp and pointed; air atoms are light and whirling, pervading all other materials

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John Dalton

6 September 1766 – 27 July 1844 in Manchester, England

Best known for his pioneering work in the development of modern atomic theory, and his research into colour blindness.

After describing experiments to ascertain the pressure of steam at various points between 0 and 100 °C (32 and 212 °F), Dalton concluded from observations on the vapor pressure of six different liquids, that the variation of vapour pressure for all liquids is equivalent, for the same variation of temperature, reckoning from vapour of any given pressure.

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Ernest Rutherford

August 1871 – 19 October 1937 in New Zealand

Became known as the father of nuclear physics and is to be considered as the greatest experimentalist since Michael Faraday (1792-1867)

in his early work he discovered the concept of radioactive half-life, proved that radioactivity involved the transmutation of one chemical element to another, also he differentiated and named alpha and beta radiation.

Won the Nobel Prize in Chemistry in 1908

Worked with J.J. Thomson on the conductive effects of X-rays on gases.

In 1902, with the help of Frederick Soddy, they produced a "Theory of Atomic Disintegration" to account for all their experiments.

Rutherford's research, and work done under him as laboratory director, established the nuclear structure of the atom and the essential nature of radioactive decay as a nuclear process. Rutherford's team, using natural alpha particles, demonstrated nuclear transmutation and later, using protons from an accelerator, demonstrated artificially-induced nuclear reactions and transmutation

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Marie Curie

Marie Skłodowska-Curie 7 November 1867 – 4 July 1934 in France

Was the first woman to win a Nobel Prize, the first person and only woman to win twice in multiple sciences, and was part of the Curie family legacy of five Noble Prizes.

Known for her pioneering research on radioactivity.

she discovered that uranium rays caused the air around a sample to conduct electricity. Using this technique, her first result was the finding that the activity of the uranium compounds depended only on the quantity of uranium present. She hypothesized that the radiation was not the outcome of some interaction of molecules but must come from the atom itself. This hypothesis was an important step in disproving the ancient assumption that atoms were indivisible.

During World War I, Curie saw a need for field radiological centres near the front lines to assist battlefield surgeons. After a quick study of radiology, anatomy, and automotive mechanics she procured X-ray equipment, vehicles, auxiliary generators, and developed mobile radiography units, which came to be popularly known as petites Curies

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Max Planck

April 23, 1858 – October 4, 1947 in Gottingen, Germany

He wont the Nobel Prize in Physics in 1918

Planck made many contributions to theoretical physics but his fame as a physicist rests primarily on his role as an originator of the quantum theory.

Max Planck's quantum theory revolutionized human understanding of atomic and subatomic processes.

In the turbulent post-war years, Planck, now the highest authority of German physics, issued the slogan "persevere and continue working" to his colleagues.

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Niels Bohr

7 October 1885 – 18 November 1962 in Coenhagen, Denmark

Made foundational contributions to understanding atomic structures and quantum theory, for which he received the Nobel Prize in Physics in 1922. Bohr was also a philosopher and a promoter of scientific research.

Bohr developed the Bohr model of the atom in which he proposed that energy levels of electrons are discrete and that the electrons revolve in stable orbits around the atomic nucleus but can jump from one energy level (or orbit) to another.

In September 1943, word reached Bohr that he was about to be arrested by the Germans, and he fled to Sweden. From there, he was flown to Britain, where he joined the British Tube Alloys nuclear weapons project, and was part of the British mission to the Manhattan Project.

Planetary models of atoms were not new, but Bohr's treatment was. Taking the 1912 paper by Darwin on the role of electrons in the interaction of alpha particles with a nucleus as his starting point, he advanced the theory of electrons travelling in orbits around the atom's nucleus, with the chemical properties of each element being largely determined by the number of electrons in the outer orbits of its atoms

Bohr became convinced that light behaved like both waves and particles, and in 1927, experiments confirmed the de Brogli hypothesis that matter (like electrons) also behaved like waves

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Erwin Schrodinger

12 August 1887 Vienna, Austria-Hungary to 4 Janurary 1961 Vienna Austria

Shared the Nobel Prize for Physics withe the British physicist P.A.M. Dirac.

was a Nobel Prize-winning Austrian physicist who developed a number of fundamental results in the field of quantum theory, which formed the basis of wave mechanics: he formulated the wave equation and revealed the identity of his development of the formalism and matrix mechanics.

Schrödinger proposed an original interpretation of the physical meaning of the wave function.

In January 1921, Schrödinger finished his first article on this subject, about the framework of the Bohr-Sommerfeld effect of the interaction of electrons on some features of the spectra of the alkali metals. Of particular interest to him was the introduction of relativistic considerations in quantum theory. In autumn 1922 he analyzed the electron orbits in an atom from a geometric point of view, using methods developed by the mathematician Hermann Weyl (1885–1955). This work, in which it was shown that quantum orbits are associated with certain geometric properties, was an important step in predicting some of the features of wave mechanics. Earlier in the same year he created the Schrödinger equation of the relativistic Doppler effect for spectral lines, based on the hypothesis of light quanta and considerations of energy and momentum.

He published the paper titled "Annalen der Physik" In this paper, he gave a "derivation" of the wave equation for time-independent systems and showed that it gave the correct energy eigenvalues for a hydrogen-like atom. This paper has been universally celebrated as one of the most important achievements of the twentieth century and created a revolution in quantum mechanics and indeed of all physics and chemistry.

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