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Lise Meitner (/ ˈ l iː z ə ˈ m aɪ t n ər / LEE-zə MYTE-nər, German: [ˈliːzə ˈmaɪtnɐ] ⓘ; born Elise Meitner, 7 November 1878 – 27 October 1968) was an Austrian-Swedish nuclear physicist who was instrumental in the discoveries of nuclear fission and protactinium.
The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment.
Nuclear fission was discovered in December 1938 by chemists Otto Hahn and Fritz Strassmann and physicists Lise Meitner and Otto Robert Frisch. Fission is a nuclear reaction or radioactive decay process in which the nucleus of an atom splits into two or more smaller, lighter nuclei and
Otto Hahn (pronounced [ˈɔtoː ˈhaːn] ⓘ; 8 March 1879 – 28 July 1968) was a German chemist who was a pioneer in the fields of radioactivity and radiochemistry.He is referred to as the father of nuclear chemistry and discoverer of nuclear fission, the science behind nuclear reactors and nuclear weapons.
The prevailing model of atomic structure before Rutherford's experiments was devised by J. J. Thomson. [1]: 123 Thomson had discovered the electron through his work on cathode rays [2] and proposed that they existed within atoms, and an electric current is electrons hopping from one atom to an adjacent one in a series.
Hydrogen was known to be the lightest element, and its nuclei presumably the lightest nuclei. Now, because of all these considerations, Rutherford decided that a hydrogen nucleus was possibly a fundamental building block of all nuclei, and also possibly a new fundamental particle as well, since nothing was known to be lighter than that nucleus.
So, element 105 was named dubnium, and element 106 was named seaborgium. The elements were placed in the periodic table’s seventh row, which is above the row of lanthanides and the row of actinides.
They determined that the relatively tiny neutron split the nucleus of the massive uranium atoms into two roughly equal pieces, contradicting Fermi. [5] This was an extremely surprising result; all other forms of nuclear decay involved only small changes to the mass of the nucleus, whereas this process—dubbed "fission" as a reference to ...