Even 150 years ago, scientists thought that the atoms that make up all matter, indivisible in nature.Modern science has long since shown that this is not so.It all started with the discovery of the electron.

discovery of the electron

At the end of the 19th century in what was then the science was a real coup.The famous scientist JJThomson (Lord Kelvin) discovered the electron, the microparticles having a negative charge.According to his theory, the electrons present in every atom.The lack of the necessary equipment can not accurately determine how the particles are arranged in the atom, and whether they are moving.Physicists could only indulge in philosophical discussions on this topic.

Lord Kelvin and proposed the first model of the atom.According to his model, the atom is a positively charged parti
cle of matter in which electrons are.Many compare this atom with cupcakes, which are interspersed with highlights.

experiments Rutherford

English physicist Ernest Rutherford is also engaged in research of the atom.His experiments have destroyed one of the postulates of physics of a microcosm of the time.This postulate was the fact that the atom - indivisible particle of matter.

By that time it was discovered the natural radioactivity of certain chemical elements.One Rutherford and used for the experiment.The experimental results have allowed to create a new model of the atom.

Rutherford irradiated gold foil with alpha particles.It so happens that some of them could pass freely through the foil, and some scattered at different angles.If the gold atoms had structure proposed by Thomson, alpha particle, which has a relatively large diameter, could only be reflected at a right angle.Thomson model was unable to explain this phenomenon, therefore, Rutherford proposed his model, which he called a planet.

According to her, the atom is the nucleus around which the electrons revolve.You can draw an analogy with the solar system: the planets revolve around the sun.Electrons move in their own orbits.

quantum theory of Bohr

planetary model of the atom in good agreement with many experiments, but to explain the existence of atoms long she could not.The thing is outdated classical ideas about the atom.An electron moving in an orbit must radiate (give) energy.After a short time (about 0.00000001 seconds) it should fall on the atom, so that the existence of the last stops.But why, then, we are all still exist and have not broken up into tiny particles?The answer to this question gave the quantum theory of Bohr.

Today, there are many models of the atom and atomic nucleus.Each of them has its advantages and disadvantages.Mankind will never be able to create the perfect model that would explain the amazing phenomena that occur in it.