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In what form (atom, ion, or compound body) is the element copper found during these transformations? We can for example demonstrate the conservation of the element copper during a sequence of chemical transformations in the laboratory of a high school. Some elements in the Universe are conserved after having undergone several transformations. Why do we say that the mass of the atom is mainly concentrated in its nucleus?.What can we say about the masses of the proton and the neutron?.What is the uncharged particle in the nucleus called?.How did chemists establish such a structure and what is its interest?.The nucleus consists of protons and neutrons according to a simple law there must be as many protons as there are electrons in orbit around the nucleus for the electric charge of the atom to be zero. The nucleus consists of protons and neutrons.
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The total number of particles in the nucleus (protons and neutrons) is denoted by □. Mass 2 000 times less than that of the proton, knowing that the mass of an electron is equal to the ratio of the mass of a proton to 2 000 - evolving on electronic layers.ġ. (neutrons), concentrated in a tiny and dense nucleus, and negative particles (electrons) - with a It presents the atom as a splitable entity with positive particles (protons) and neutral particles It is still in use today and is also called the simplified atomic model. The Rutherford atomic model modified by Bohr and improved by Chadwick is called the He explained that it was the neutrons that prevented the nucleus from bursting by their presence in it. In order to account for the existence of neutrons, Chadwick improved the current model of the atom. In 1932, the English physicist James Chadwick, one of Rutherford's students, proved that these penetrating rays, which had not been identified by physicists, contained a particle with no electric charge and a mass equal to that of a proton. However, this ray was impossible to be directly detected.
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When Rutherford demonstrated the existence of the proton, a new problem was raised: How do positively charged protons overcome the electric repulsion force that would normally drive them apart and cause the nucleus to burst?ġ919, some physicists had discovered a very penetrating ray by bombarding beryllium with alpha particles. Thomson discovered the electron, Rutherford showed that matter is essentially empty, and Bohr helped explain why the electrons in Rutherford's model did not crash into the nucleus.