Founders of Atomic Theory

Democritus

Democritus was born in Abdera, around 460 BCE, some say in the range of 490. His dad was from an honorable family and of extraordinary riches, and contributed to a great extent towards the diversion of the military of Xerxes on his arrival to Asia. After the death of his dad, he went looking for wisdom, and gave his legacy to this reason, adding up to one hundred gifts. He is said to have visited Egypt, Ethiopia, Persia, and India. Following quite a while of voyaging, Democritus returned to Abdera, without any methods for subsistence. His sibling Damosis, nonetheless, took him in.

In the atomist form, these constant material standards are resolute particles. Atoms are from the Greek descriptive word ‘atomos’ or ‘atomon’, ‘indissoluble’, are interminable in number and fluctuated fit as a fiddle, and superbly strong, with no interior holes. They move about in an unbounded void, repulsing each other when they impact or joining into groups by methods for modest snares and points on their surfaces, which become caught. Other than evolving place, they are unchangeable, ungenerated and indestructible. All adjustments in the obvious objects of the universe of appearance are achieved by migrations of these molecules: in Aristotelian terms, the atomists diminish all change to change of place. Democritus’ nuclear hypothesis contended from derivation and perception as opposed to test that everything is made of atoms. Molecules are the smallest particles of issue – too little for us to see. Particles have existed always, particles are unbreakable, iotas can't be obliterated. Molecules have been moving everlastingly and will stay moving perpetually and noticeable changes are brought about by improvements and developments of molecules.

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Neils Bohr

Niels Henrik David Bohr was born in Copenhagen, Denmark on October 7, 1885, as the son of Christian Bohr, Professor of Physiology at Copenhagen University, and his wife Ellen, née Adler. His father was an eminent physiologist and was largely responsible for awakening his interest in physics while still at school, his mother came from a family distinguished in the field of education. After matriculation at the Gammelholm Grammar School in 1903, he entered Copenhagen University where he came under the guidance of Professor C. Christiansen, a profoundly original and highly endowed physicist, and took his Master’s degree in Physics in 1909 and his Doctor’s degree in 1911. In 1913-1914 Bohr held a Lectureship in Physics at Copenhagen University and in 1914-1916 a similar appointment at Victoria University in Manchester. In 1916 he was appointed Professor of Theoretical Physics at Copenhagen University, and since 1920 (until his death in 1962) he was at the head of the Institute for Theoretical Physics, established for him at that university. Recognition of his work on the structure of atoms came with the award of the Nobel Prize for 1922. Bohr also contributed to the clarification of the problems encountered in quantum physics, in particular by developing the concept of complementarity. During the Nazi occupation of Denmark in World War II, Bohr escaped to Sweden and spent the last two years of the war in England and America, where he became associated with the Atomic Energy Project. In his later years, he devoted his work to the peaceful application of atomic physics and to political problems arising from the development of atomic weapons. In 1912 Bohr married Margrethe Norlund. They had six sons, one of whom, Aage, followed his father into physics - and into the ranks of Nobel Prize-winners. After Hitler took power in Germany, Bohr was deeply concerned for his colleagues there, and offered a place for many escaping Jewish scientists to live and work. He later donated his gold Nobel medal to the Finnish war effort. In 1939 Bohr visited the United States with the news from Lise Meitner (who had escaped German-occupied Austria) that German scientists were working on splitting the atom. This spurred the United States to launch the Manhattan Project to develop the atomic bomb. Shortly after Bohr's return home, the German army occupied Denmark.

Niel Bohr’s atomic theory states that – an atom is like a planetary model where electrons were situated in discretely energized orbits. The atom would radiate a photon when an excited electron would jump down from a higher orbit to a lower orbit. The difference between the energies of those orbits would be equal to the energy of the photon.

JJ Thomson

Joseph John Thomson was born in Cheetham Hill, a suburb of Manchester on December 18, 1856. He enrolled at Owens College, Manchester, in 1870, and in 1876 entered Trinity College, Cambridge as a minor scholar. 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. In 1896, Thomson visited America to give a course of four lectures, which summarized his current researches, at Princeton. 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, which was announced during the course of his evening lecture to the Royal Institution on Friday, April 30, 1897. Thomson returned to America in 1904 to deliver six lectures on electricity and matter at Yale University. They contained some important suggestions as to the structure of the atom. He discovered a method for separating different kinds of atoms and molecules by the use of positive rays, an idea developed by Aston, Dempster and others towards the discovery of many isotopes. In 1890, he married Rose Elisabeth, daughter of Sir George E. Paget. They had one son, now Sir George Paget Thomson, Emeritus Professor of Physics at London University, who was awarded the Nobel Prize for Physics in 1937, and one daughter. In 1904 Thomson suggested a model of the atom as a sphere of positive matter in which electrons are positioned by electrostatic forces.

John Dalton

Dalton was born into a modest Quaker family in Cumberland, England, and for most of his life - beginning in his village school at the age of 12 - earned his living as a teacher and public lecturer. Both of his parents were Quakers. As a result of this, John Dalton’s higher educational opportunities were restricted to dissenting places of education. The first paper he delivered before the society was on color blindness, which afflicted him and is sometimes still called ‘Daltonism’. In 1794, he wrote his first scientific paper which he called: ‘Extraordinary Facts Relating to the Vision of Colors’.

He proceeded to calculate atomic weights from percentage compositions of compounds, using an arbitrary system to determine the likely atomic structure of each compound. If there are two elements that can combine, their combinations will occur in a set sequence. Dalton’s atomic theory states that: elements are made of atoms which are tiny particles too small to see, all atoms of a particular element are identical, atoms cannot be created, destroyed, or split.

Ernest Rutherford

Ernest Rutherford was born on August 30, 1871, in the village of Brightwater on New Zealand’s South Island. His father, James Rutherford, was a farmer from Scotland and his mother, Martha Thompson, was a schoolteacher from England. In 1895 he obtained a bachelor’s degree in chemistry and geology from Canterbury College and spent a short time working as a schoolteacher. He won an overseas study scholarship and decided to go to the University of Cambridge in the United Kingdom to work in J. J. Thomson’s laboratory. After his move to the University of Manchester, Rutherford and two of his researchers Hans Geiger and Ernest Marsden carried out in 1909 one of the landmark experiments in science, the gold foil experiment. Rutherford began the experiment because he was puzzled, that fewer alpha particles than expected from a sample of radium were reaching a new detector in his laboratory. The only medium the particles had to travel through was a small amount of air. Rutherford thought the huge amount of energy carried by alpha particles should have allowed them to travel through a small amount of air undisturbed, with no deflection. It was Sir J.J. Thomson who first discovered that the atom wasn’t indivisible after all, a notion believed to be true for centuries. However, the subatomic particle he discovered was negatively charged. If atoms were merely a cluster of negative charges, then chairs, tables, you and I would be anything but stable. He immediately realized that to account for matter’s stability, there must be a net positive charge to neutralize the negativity.

Erwin Schrodinger

Erwin Schrodinger was born on August 12, 1887, in Vienna, the only child of Rudolf Schrödinger, who was married to a daughter of Alexander Bauer, his Professor of Chemistry at the Technical College of Vienna. From 1906 to 1910 he was a student at the University of Vienna, during which time he came under the strong influence of Fritz Hasenöhrl, who was Boltzmann’s successor. It was in these years that Schrodinger acquired a mastery of eigenvalue problems in the physics of continuous media, thus laying the foundation for his future great work. In the early 1920’s, the primary evidence for the nature and action of subatomic particles came from indirect observations, for example, from noting the spectral lines formed when light passed through prisms. Schrodinger began experimental work in color and light, collaborating with prominent scholars. His book ‘What is life?’, published in 1944 relates quantum physics to genetics had a profound effect on the future of genetics and molecular biology. His last publication ‘Meine Weltansicht’ (My World View) was published in 1962.

James Chadwick

James Chadwick was born in the small town of Bollington, England, UK on October 20, 1891. His parents were Joseph, a railway storekeeper, and Anne, a domestic servant. When he was 11, James won entry to the prestigious Manchester Grammar School. Unfortunately, his parents were too poor to afford the modest school fees. Instead, James Chadwick was educated at Manchester’s Central Grammar School for Boys. Aged 16, he won a scholarship to the Victoria University of Manchester. In 1914, Chadwick decided to travel to Germany to study with Hans Geiger. Unfortunately, not long after he arrived, World Waw I broke out and Chadwick ended up spending the next four years in a prison camp there. This did not entirely stop his scientific studies. To keep from being bored, he and some fellow prisoners formed a science club, lectured to each other, and managed to convince the guards to let them set up a small lab. Though many chemicals were hard to get hold of, Chadwick even found a type of radioactive toothpaste that was on the market in Germany at the time, and managed to persuade the guards to supply him with it. Using some tin foil and wood he built an electroscope and did some simple experiments. Chadwick is best known for his discovery of the neutron in 1932. A neutron is a particle with no electric charge that, along with positively charged protons, makes up an atom's nucleus. Bombarding elements with neutrons can succeed in penetrating and splitting nuclei, generating an enormous amount of energy. In this way, Chadwick's findings were pivotal to the discovery of nuclear fission, and ultimately the development of the atomic bomb. James Chadwick discovered the neutron in 1932 and was awarded the Nobel Prize for Physics in 1935.

Werner Heisenberg

Werner Heisenberg was born on 5th December, 1901, at Würzburg. He was the son of Dr. August Heisenberg and his wife Annie Wecklein. His father later became Professor of the Middle and Modern Greek languages in the University of Munich. Heisenberg went to the Maximilian school at Munich until 1920, when he went to the University of Munich to study physics under Sommerfeld, Wien, Pringsheim, and Rosenthal. At the end of the Second World War, he and other German physicists were taken prisoner by American troops and sent to England, but in 1946 he returned to Germany and reorganized, with his colleagues, the Institute for Physics at Göttingen. This Institute was, in 1948, renamed the Max Planck Institute for Physics. Heisenberg is best known for his uncertainty principle and theory of quantum mechanics, which he published at the age of twenty-three in 1925. He was awarded the Nobel Prize for Physics in 1932 for his subsequent research and application of this principle. His new theory was based only on what can be observed, that is to say, on the radiation emitted by the atom.

Louis De Broglie

Born in Dieppe, France on 15 August in 1892, Louis de Broglie grew up in a rich, aristocratic family. Prince Louis-Victor de Broglie of the French Academy, Permanent Secretary of the Academy of Sciences, and Professor at the Faculty of Sciences at Paris University, was born at Dieppe (Seine Inférieure) on 15th August, 1892, the son of Victor, Duc de Broglie and Pauline d’Armaillé. Then, as his liking for science prevailed, he studied for a science degree, which he gained in 1913. He was then conscripted for military service and posted to the wireless section of the army, where he remained for the whole of the war of 1914-1918. During this period, he was stationed at the Eiffel Tower, where he devoted his spare time to the study of technical problems. At the end of the war Louis de Broglie resumed his studies of general physics. Most of the work in Maurice’s lab involved X-rays, which made Louis think about the dual nature of light; more particularly the wave–particle duality. Broglie soon suggested in his thesis for a doctorate degree that matter, also, might behave in a similar manner. His thesis, ‘Recherches sur la théorie des quanta’ (Research on the Theory of the Quanta), centered on his revolutionary theory of electron waves. When the French Academy became aware of his theory of electron waves, it caught Albert Einstein’s attention, who had high praise for Broglie’s bold ideas. That inspired the birth of wave mechanics.

Broglie’s theory resolved and offered an explanation to a question that was brought up by calculations of the motion of electrons within the atom. It was later independently proved in 1927 by G.P. Thomson and Clinton Davisson and Lester Germer that matter actually could show wave-like characteristics. Louis de Broglie won the 1929 Nobel Prize in Physics for his amazing work. Broglie stayed at the Sorbonne after earning his doctorate, being appointed a professor of theoretical physics at the newly-established Henri Poincaré Institute in 1928, where he remained until his retirement in 1962.