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460 BCE
Democritus Biography
He was born 460 BCE— died c. 370. He is the central figure in the development of philosophical atomism and of the atomic theory of the universe. His rival was Aristoteles. He theorized that all material bodies are made up of indivisibly small “atoms”. -
400 BCE
Democritus Discovery
He took a simple seashell and break it in half. He then took that half and broke it in half over and over and over and over again until he was finally left with a fine powder. He then took the smallest piece from the powder and tried to break that but could not. So thus Democritus had discovered what was the indivisible building block of life the atom. -
Jhon Dalton Biography
He was born on September 5 or 6, 1766, Eaglesfield, Cumberland, England-died July 27, 1844, in Manchester. Dalton was born into a Quaker family of tradesmen. At his 12 years old he started teaching. At the New College in Manchester, he became a math and philosophy tutor. -
Jhon Dalton Discovery
He based his theory of partial pressures on the idea that only atoms in a mixture of gases repel one another, whereas unlike atoms appear to react indifferently toward each other. Dalton's experiments on gases led to his discovery that the total pressure of a mixture of gases amounted to the sum of the partial. -
William Crookes Biography
Born June 17, 1832, London, Eng.—Died April 4, 1919, London. One of the most important scientists in 19th century Europe, both in the field of physics and chemistry. He was the inventor of the cathode ray tube, for the discovery of the element thallium, and for being the first to analyze helium gas in the laboratory. He enjoyed remarkable popularity, and his personality and achievements are well known. -
J.J. Thomsons Biography
He was born on December 18th 1857 and died on August 30 1940. He studied engineering in 1870. He won his mathematics license in 1880. One of his students was Ernest Rutherford, who later on became his successor. He became part of the royal society and later on its president during the years 1915-1920. In 1884 he married Rose Elizabeth Paget and had two children, George Paget Thomson, and Joan Paget Thomson. After his discovery, he won a physics Nobel prize in 1906. -
William Crookes Discovery
He discovered the Crookes radiometer, a device that converts light radiation into rotary motion. Discovered the element thallium and show there is a negative charge in atoms. He created a Crookes tube that consists of a partially evacuated glass bulb of various shapes, with two metal electrodes, the cathode, and the anode, one at either end. When a high voltage is applied between the electrodes, cathode rays are projected in straight lines from the cathode. -
Robert Millikan Biography
Robert Millikan was born in 1868 and grew up in rural Iowa, the second son of a minister. Millikan attended Oberlin College, earned his PhD from Columbia University, and then spent a year in Germany before taking a position at the University of Chicago. By about 1906, Millikan had become a successful educator and textbook writer, but he hadn’t done any real scientific significance and was eager to make his mark. In 1923 Millikan was awarded the Nobel Prize in Physics. -
Ernest Rutherford Biograhy
Born 30 de Agosto de 1871 Brightwater, New Zealand - Died 19 de Octubre de 1937. He was noted for his ability to arithmetic. He turned out to be a brilliant student, which allowed him to enter Nelson College. He also had great qualities for rugby, which earned him being very popular at his school. He finished first in all subjects, thanks to which he entered the University, Canterbury College, in which he continued to play rugby and participated in the science and reflection clubs. -
Niels Bohr Biography
Born in Copenhagen, Denmark on October 7, 1885- Died November 18, 1962, Carlsberg, Copenhagen, Denmark. He grew up in an atmosphere most favourable to the development of his genius – 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. -
Erwin Schrodinger Biography
Born August 12, 1887, Vienna, Austria—died January 4, 1961, Vienna, who contributed to the wave theory of matter and to other fundamentals of quantum mechanics. He was a highly gifted man with a broad education. After having finished his chemistry studies, he devoted himself for years to Italian painting. After this, he took up botany, which resulted in a series of papers on plant phylogeny. He had a wide interest in severe logic of ancient grammar and the beauty of German poetry. -
Henry Gwyn Jeffreys Moseley Biography
Born November 23, 1887, Weymouth, Dorset, England—died August 10, 1915, in Gallipoli, Turkey. He was an English physicist who experimentally demonstrated that the significant properties of an element. Moseley enlisted in the army when World War I broke out in 1914 and that's how he died when his group was settled in turkey. -
James Chadwick Biography
Born in Cheshire, England, on 20th October 1891- July 24, 1974, Cambridge, UK. He attended Manchester High School prior to entering Manchester University in 1908; he graduated from the Honours School of Physics in 1911 and spent the next two years under Professor (later Lord) Rutherford in the Physical Laboratory in Manchester, where he worked on various radioactivity problems, gaining his M.Sc. degree in 1913. -
J.J. Thomson Scientific Discovery
His objective was to find what were the mysterious rays that glowed when electricity was applied to metal. When he moved a magnet near a tube modified to reveal rays, he saw that it bent the path of that beam. He showed that an electric current consists of flowing negatively charged particles– what soon came to be called “electrons.” when he used different metals to generate the rays, the resulting electrons were always the same. The conclusion was that an electron must be a piece of every atom. -
Ernest Rutherford Discovery
He postulated the nuclear structure of the atom, discovered alpha and beta rays and proposed the laws of radioactive decay. His laboratory showed that when alpha particles are fired into gas atoms, a few are violently deflected, which implies a dense, positively charged central region containing most of the atomic mass. He received the Nobel Prize in Chemistry. -
Robert Millikan Discovery
He varied the electric voltage between two metal plates as an oil drop fell between them until the drop stopped falling. When the drop was stationary, the downward force of gravity on the drop equalled the upward electrical force on the charges in the drop, and then Millikan could measure how much charge the drop had. -
Niels Bohr Discovery
He was the first to apply the quantum concept, which restricts the energy of a system to certain discrete values, to the problem of atomic and molecular structure. Technically he drew how the atom worked and mostly concentrated on how electros would move around the nucleus. -
Henry Gwyn Jeffreys Moseley Discovery
He demonstrated that the significant properties of an element are determined by the atomic number, not by the atomic weight, and firmly established the relationship between atomic number and the charge of the atomic nucleus. He concluded that the atomic number is the number of positive charges in the atomic nucleus. He discovered a systematic relation between wavelength in X-ray spectra and in the atomic number. -
Erwin Schrodinger Discovery
Introduced a theory describing the behaviour of particles of matter having a dual nature and in some situations acting like waves. He produced papers which described partial differential equation, that is the basic equation of quantum mechanics and bears the same relation to the mechanics of the atom as Newton’s equations of motion bear to planetary astronomy. -
James Chadwick Discovery
Rutherford and he studied the transmutation of elements by bombarding them with alpha particles and investigated the nature of the atomic nucleus, identifying the proton, the nucleus of the hydrogen atom, as a constituent of the nuclei of other atoms.He had discovered the neutron.
