Ernest Rutherford - a unique, very talented and very unusual scientist.It should be noted that the most important discoveries have been made by him after he received the Nobel Prize.In 1911, this man was a success experience Rutherford (so it was named later), which allowed to look inside the atom and get some idea of how it works.
Numerous experiments with atoms held previously.Their main idea was that at different angles of deflection of particles to gather sufficient information on which would be able to say something concrete about the structure of the atom.In the early 20th century, scientists were convinced that it contains electrons, negatively charged.However, the most widely used at the time to get an idea that the atom is a positively charged like a thin mesh which is filled with electrons with a negative charge.This model is called the "grid with raisins."
Rutherford was a unique experience.Scientists have built a cannon, which gave a focused and directed a stream of particles.She looked like a leaden box, which has a narrow slit.Inside it was placed radioactive material.Alpha particles, which are emitted by a radioactive substance in all areas except one, have been absorbed by a screen of lead, and only through the slot flew determine the direction the particle beam.On his way then it sets a few screens of lead with slits that cut off particles that deviate from the desired direction.As a result of the experience of Rutherford flew up to target a focused particle beam, the target is in itself a very thin sheet of foil.It's the hit alpha ray.
After alpha particles collide with atoms of the foil, they continued on their way, and eventually appeared on the luminescent screen that was installed behind the target.When the particles hit the screen, it recorded outbreaks for which the experimenter could tell how much and how many alpha particles are deflected by the forward direction of movement of the collision with the atoms of gold foil.
Experience Rutherford was so original because of the fact that no one before him did not try to check, whether certain particles are deflected at large angles.The old model of the grid did not allow even the existence of so heavy and dense elements in the atom, so that they could reject the very fast alpha particles at a sufficiently large angle.
experience allowed Rutherford to conclude that most of the mass is concentrated in very dense matter, which is located in the heart of the atom.The rest part was in reality much less dense than it seemed earlier.Rutherford atom contained hyperdense center, which has been called the nucleus, which, incidentally, was concentrated positive charge.
picture of the atom, which drew a scientist, we are now already well known.Rutherford's model is that the center is located in the nucleus with a positive charge, which concentrated all the mass of the atom.In general, the atom is neutral.Therefore, the number of electrons inside, as well as the nuclear charge, equal to the number in the periodic system.It is understood that the electrons can not rest inside atom, since they simply fall to the core.They move around much the same way as planets revolve around the sun.
Such character of the movement define the action of Coulomb forces from the nucleus.Atoms are stable in the unexcited state may exist for long amounts of time, it does not emit any electromagnetic waves.However, the planetary model of the atom, though it proved experimentally, can not explain why it is stable.