when was this formulated?
1911
Rutherford model
Rutherford presented 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 May 1911 paper, Rutherford only committed himself to a small central region of very high positive or negative charge in the atom.
a medium of free floating positive and negative charges is called a(n) Plasma what can you tell me about the physical properties of electron? The electric charge is negative one elementary charge; its mass is approximately 1/1836 that of the proton; exhibit properties of both particles and waves: they can collide with other particles and can be diffracted like light. where can you see its use? In the electron microscope; free-electron laser (FEL); cathode ray tubes; in welding;  Electron beam processing is used to irradiate materials in order to change their physical properties or sterilize medical and food products. were there any theories based on it? Yes - experiments by physicists Ernest Rutherford, Henry Moseley, James Franck and Gustav Hertz had largely established the structure of an atom as a dense nucleus of positive charge surrounded by lower-mass electrons. can you elaborate on the initial physicist's theory? He formulated the Rutherford model of the atom in 1911 that a very small charged nucleus, containing much of the atom's mass, was orbited by low-mass electrons.
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Rutherford model [SEP] Experimental basis for the model
In this May 1911 paper, Rutherford only committed 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 "N" "e", and surrounded by a compensating charge of "N" electrons. From purely energetic considerations of how far 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 × 10 metres.