The Rutherford model or planetary model is a model of the atom devised by Ernest Rutherford. Rutherford directed the famous Geiger-Marsden experiment in 1909, which suggested on Rutherford's 1911 analysis that the so-called "plum pudding model" of J. J. Thomson of the atom was incorrect. Rutherford's new model[1] for the atom, based on the experimental results, had the new features of a relatively high central charge concentrated into a very small volume in comparison to the rest of the atom and containing the bulk of the Atomic Mass (the nucleus of the atom).
Rutherford's model did not make any new headway in explaining the electron-structure of the atom; in this regard Rutherford merely mentioned earlier atomic models in which a number of tiny electrons circled the nucleus like planets around the sun, or a ring around a planet (such as Saturn). However, by implication, Rutherford's concentration of most of the atom's mass into a very small core made a planetary model an even more likely metaphor than before, as such a core would contain most of the atom's mass, in an analogous way to the Sun containing most of the solar system's mass.
Experimental basis for the modelIn 1911, Rutherford came forth with his own physical model for subatomic structure, as an interpretation for the unexpected experimental results. In it, the atom is made up of a central charge (this is the modern atomic nucleus, though Rutherford did not use the term "nucleus" in his paper) surrounded by a cloud of (presumably) orbiting electrons. In this 1911 paper, Rutherford only commits himself to a small central region of very high positive or negative charge in the atom."For concreteness, consider the passage of a high speed α particle through an atom having a positive central charge Ne, and surrounded by a compensating charge of N electrons." [2]
From purely energetic considerations of how far alpha particles of known speed would be able to penetrate toward a central charge of 100 e, Rutherford was able to calculate that the radius of his gold central charge would need to be less (how much less could not be told) than 3.4 x 10−14 metres (the modern value is only about a fifth of this). This was in a gold atom known to be 10−10 metres or so in radius-a very surprising finding, as it implied a strong central charge less than 1/3000th of the diameter of the atom.
The Rutherford model served to concentrate a great deal of the atom's charge and mass to a very small core, but didn't attribute any structure to the remaining electrons and remaining atomic mass. It did mention the atomic model of Hantaro Nagaoka, in which the electrons are arranged in one or more rings, with the specific metaphorical structure of the stable rings of Saturn. The so-called plum pudding model of J.J. Thomson had also had rings of orbiting electrons.
The Rutherford paper suggested that the central charge of an atom might be "proportional" to its atomic mass in hydrogen mass units u (roughly 1/2 of it, in Rutherford's model). For gold, this mass number is 197 (not then known to great accuracy) and was therefore modeled by Rutherford to be possibly 196 u. However, Rutherford did not attempt to make the direct connection of central charge to atomic number, since gold's place on the Periodic Table was known to be about 79 u, and Rutherford's more tentative model for the structure of the gold nucleus was 49 helium nuclei, which would have given it a mass of 196 u and charge of 98 e, which was much more in keeping with his experimentally-determined central charge for gold in this experiment of about 100 e. This differed enough from gold's "atomic number" (at that time merely its place number in the periodic table) that Rutherford did not formally suggest the two numbers (atomic number and nuclear charge) might be exactly the same.
A month after Rutherford's paper appeared, the proposal regarding the exact identity of atomic number and nuclear charge was made by Antonius van den Broek, and later confirmed experimentally within two years, by Henry Moseley.
Key pointsLater on, scientists found the expected number of electrons (the same as the atomic number) in an atom by using X-rays. When an X-ray passes through an atom, some of it is scattered, while the rest passes through the atom. Since the X-ray loses its intensity primarily due to scattering at electrons, by noting the rate of decrease in X-ray intensity, the number of electrons contained in an atom can be accurately estimated.
What are the success of rutherford s experiment
The gold-foil experiment
ernest Rutherford
Ernest James Rutherford.
Rutherford discovered Nitrogen in 1772.
Ernest Rutherford
why was Ernest Rutherford's nickname lord Rutherford
Rutherford
Hannah Rutherford was his mum and Davis Rutherford was his dad
Margaret Rutherford's birth name is Margaret Taylor Rutherford.
Camilla Rutherford's birth name is Camilla Claude Rutherford.
Gene Rutherford's birth name is Robert Eugene Rutherford.
Kelly Rutherford's birth name is Kelly Rutherford Deane.
Rustee Rutherford's birth name is Rustee Meghan Rutherford.
The address of the Rutherford Free Pub. Lib. is: 150 Park Avenue, Rutherford, 07070 M
The gold-foil experiment
ernest Rutherford
Eileen Rutherford