Rutherford, Ernest atomic structure model

Ernest Rutherford studied atomic structure in 1910-1911 by firing a beam of alpha particles at thin layers of gold leaf. According to Thomson s model, the path of an alpha particle should be deflected only slightly if it struck an atom, but Rutherford observed some alpha particles bouncing almost backwards, suggesting that nearly all the mass of an atom is contained in a small positively charged nucleus. 

To learn more about the discovery of atomic structure, visit the Chemistry Web site at chemistrymc.com Activity Research Ernest Rutherford s work. Write a newspaper article announcing his model of the atom. 

Soon after Thomson developed his model, tremendous insight into atomic structure was provided by one of Thomson s former students, Ernest Rutherford (1871-1937), who was the outstanding experimental physicist of his time. 

Several major discoveries at the turn of the 20 century ied to our current model of atomic structure. Cathode rays were shown to consist of negative particles (electrons) that exist in ail matter. J. J. Thomson measured their mass/charge ratio and con-ciuded that they are much smalier and iighter than atoms. Robert Miliikan determined the charge of the electron, which he combined with other data to calculate its mass. Ernest Rutherford proposed that atoms consist of a tiny, massive, positive nucleus surrounded by electrons. 

The basic structure of an atom consists of a nucleus surrounded by a cloud of electrons. This is the nuclear atom , the model of an atom first identified by Ernest Rutherford (1871-1937) in 1911. The nucleus is positively charged, the electrons are negatively charged, and it is the attrartion between these opposite charges that is responsible for the existence and survival of the atom. As is well known, atoms are very small there are over a million carbon atoms in (the printed version of) the full stop at the end of this sentence. A nucleus is even smaller if an atom were enlarged to the size of a football stadium, the nucleus would be the size of a fly at its centre. 

The plum pudding model, a batter of positive charge with minute negative currants embedded in it, appeared to be consistent with experiments which showed that a beam of electrons could pass undeflected through a thin metallic foil. In other words, one might conclude, as Philipp Lenard (1862-1947) did in 1903, that the atom was mostly empty space. These data as well as the larger question about the inner structure of the atom prompted a most provocative line of experimentation by Ernest Rutherford (1871-1937). Manchester University was the site of these historical experiments, which Rutherford initiated soon after he arrived in 1907 to assume his responsibilities as Langworthy Professor of Physics. 

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