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Discovery of Radiation
The first effects of radiation was not seen untill 1896, whene Nikola Tesla subjected his fingers to X-rays and reported that this caused burns to develop. But the whole totally effects of radition was not relized until decades later. The cancer risk associated with radiation exposure were first recognized by Hermann Joseph Meller in 1927. But the -
Discovery of electrons, protons
In 1897 Thomson discovers the electron, After the discovery of the electron, it was realized that there must be positive charge centers within the atom to balance the negative electrons and create electrically neutral atoms. This lader led to the dicoveryes in 1911 and in 1932. -
The plum puuding model
Thomsom's atomic model, was a discreption of the inner structure of atoms. Sir Joseph John Thomson, who had discovered the electron and, the negatively charged part of every atom. Thomson held that atoms are uniform spheres of positively charged matter in which electrons are embedded. The plum pudding modale ad to be abandoned on both theoretical and experimental grounds in favour of the Rutherford atomic model, in which the electrons describe orbits about a tiny positive nucleus. -
The discovery of the nucleus
1911 Rutherford discovers the nucleus, The modle that Rutherfrod made was called nuclear atom or planetary model of the atom. His 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. -
The Bohr model - The atom with orbitals
A danish physicist named, Niels Bohr who had studied Thomson and Rutherford, he than refined the nuclear model by proposing that electrons moved only in restricted, successive orbital shells and that the outer, higher-energy orbits determined the chemical properties of the different elements. Bohr was able to explain the spectral lines of the different elements by suggesting that as electrons jumped from higher to lower orbits. In the 1920s, Bohr's theory became the basis for quantum mechanics, -
The discovery of the neutron
In 1932 Chadwick discovers the neutron. In a few year thier were sinteinces that were investigators throughout the world were studying the properties and interactions of the particle. Thier are vieuruas elements when bombarned by nutrions, they undergo fission wich is a teyp of nucerluer reaction. -
Harnessing Nucler Fission
Hahn and Strassmann showed that fission not only released a lot of energy but that it also released additional neutrons which could cause fission in other uranium nuclei and possibly a self-sustaining chain reaction leading to an enormous release of energy. Bohr than proposed that fission was much more likely to occur in the uranium-235 isotope than in U-238 and that fission would occur more effectively with slow-moving neutrons than with fast neutrons, the latter point being confirmed by Szilar -
The first atomic bomb test
Plans for the creation of a uranium bomb by the Allies were established as early as 1939. When the Project took final form in the desert of New Mexico, where, in 1943, Robert J. Oppenheimer began directing Project Y at a laboratory at Los Alamos, along with such minds as Hans Bethe, Edward Teller, and Fermi. In the morning of july 16, ,in the New Mexico desert120 miles south of Santa Fe, the first atomic bomb was detonated.