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the elements are constituted by atoms,the atoms of the same elements are equal to each other,compounds are formed and in a chemical reaction the atoms regroup
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discovered some rays that were characterized by not constituted by electric charges and are capable of passing through thick materials
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a year later a disciple of Becquerel suggested the name of radioactivity to describe the spontaneous emission of radiation by some substances that are called radioactive
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the cathode rays are formed by material particles much smaller than the atom and with a negative electric charge
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states that the atom is a positively charged sphere in which electrons are embedded it was based on an experiment called``the raisin cake mode´´
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the atom consists of a very small part called nucleus, positively charged and contains almost all of the mass
around the nucleus, in the cortex, electrons move.
the atom is electrically neutral -
the electrons are in electronic layers rotating in orbits, in these orbits the electron neither absorbs nor emits energy, but when it jumps from one orbit to another if it absorbs or emits energy
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the scientists proposed the called mechano-quantum model
