Scientists do not immediately come to a correct understanding of atomic structure.The first model of the atom proposed English physicist George. George. Thomson, discoverer of the electron.But his model came into conflict with the experiments of Rutherford on the distribution of the positive charge in the microparticle.These experiments Rutherford played a major role in understanding the workings of the atom.
It was already known that the electron mass is thousands of times smaller than the mass of the particle itself.Rutherford made the assumption that because the whole atom is neutral, the bulk of its weight should fall on the positively charged part.To confirm this hypothesis, Rutherford's experiments were limited to the following.
He suggested using alpha particles to probe the atom.The electron mass about 8,000 times less than that of α-particles and their rate is very high - it can be up to twenty thousand kilometers per second.It was Rutherford's experiments on the scattering of alpha particles.
atoms of heavy elements bombarded by these particles.Because of the small mass of the electrons to change the trajectory of α-particles could not be much.It could only do part of the atom positively charged.Consequently, the nature of alpha-particle scattering can be found in the distribution of mass and substance microparticles a positive charge.
experiments Rutherford had the following scheme.Any radioactive substance is placed inside the cylinder of lead.This cylinder longitudinally drilled a narrow channel.The flow of α-particles from the channel falling on a thin foil of the studied material (copper, gold, etc.).Then, alpha particles falling on a translucent screen that was covered with zinc sulfide.Each particle, colliding with the screen, giving a flash of light (scintillation), it could be seen through a microscope.
Rutherford Further experiments have shown that a small number of alpha particles (about one in two thousand) deflected by an angle greater than 90 °.This fact greatly puzzled Rutherford.He said that it is just as incredible as a projectile fired at a piece of tissue paper and it came back to you and stabbed.Indeed, to predict an outcome based on the Thomson model, it is impossible, and Rutherford suggested that the α-particle can be pushed back only when the bulk of the atom is in a very small volume of space.Since Rutherford's experiments helped him to come to the model of the nucleus.This body is of small size, which concentrated almost all the positive charge and the entire mass of microparticles.
atomic model follows directly from experiments, which spent Rutherford.The structure of the atom by Rutherford following conception.Positively charged nucleus in the center.Since the atom is neutral, the number of electrons equals the atomic number in Mendeleev's periodic system.They move in a circle on the core, as the planets revolve around the Sun in their orbits.The motion of electrons due to Coulomb forces.The hydrogen atom has only one electron orbiting its nucleus.Its nucleus carries a positive charge and a mass of about 1836 times the mass of the electron.
Such a model of the atom had experimental basis, but based on this model can not explain the stability of its existence.
Electrons moving in an orbit, should according to the laws of classical mechanics closer to the nucleus due to the loss of energy and, in the end, fall on him.Actually, the electron falls into the nucleus.The microparticles of chemical elements are very stable and can exist for a very long time.The conclusion of the imminent destruction of the atom due to the loss of energy that is not consistent with the experiments of Rutherford, is a result of the application of the laws of classical mechanics to the micro-scale phenomena.Therefore, the phenomena of the microworld applicable laws of classical physics.
