Niels Bohr - the famous Danish scientist who first proved the incompatibility of the classical laws of physics and atoms.In this regard, he introduced two assumptions, now known as the Bohr quantum postulate.They are based on the model of the atom, once proposed by E. Rutherford, according to which he (the atom) has a structure similar to the structure of the universe: the electrons of an atom are in continuous motion around a fixed particles - the nucleus.At first, this model is considered ideal and fully describe and explain all the experiences related to the atom.But later it became clear that to answer the question on the existence of the atom and its stability, this model is not able to.
According to the planetary model, the movement of electrons around a fixed nucleus must necessarily be accompanied by the emission of electromagnetic waves having a frequency equal to the frequency of rotation of the negatively charged elements around the center.As a result - the electron energy should continue to decrease, which in turn leads to its greater attraction to the nucleus.However, as experience shows, this is not happening.Atom is the general stability of the system can exist without a long period of exposure to outside influence.The emission of an atom can be called a discrete, ieintermittent, which, of course, points to the fact the frequency of learning rather than its permanence.In other words, the researchers concluded that the use of the classical laws of physics to explain the existence of electrons is impossible.
only in 1913 introduced by Bohr assumptions used to explain an example of a hydrogen atom principles of radiation energy electrons.
conclusions made by Bohr, were empirically confirmed by many scientists of that time.On the basis of its assumptions it has created an entire theory, which later became a special case of quantum mechanics.Bohr's postulates are as follows:
1. Nuclear power system emits energy, conventionally called En, only being in quantum states.Otherwise (when finding the atom in the steady state), the energy is not released.
In this case, under the steady state refers to the movement of electrons in certain orbits.Although the actual availability of accelerated motion, electromagnetic waves are not emitted, the atom has a quantum energy value.
2. The second postulate, often known as a rule frequencies, suggests that the transition of an atom from one state to another (usually in a stationary quantum) is accompanied by the release or absorption of energy.This process is carried out in small portions - quanta.Their value corresponds to the energy difference of states between which the transition actually takes place.The second postulate allows us to calculate the known experimental values of the energies of the stationary states of the radiation frequency of the hydrogen atom.
Bohr's postulates are useful for explaining the absorption and emission of light by a particle of hydrogen.Actually, it is thus confirmed once their findings Bohr himself.Bohr's postulates have allowed modern scientists to construct a theory of the hydrogen spectrum.It is noteworthy that the construction of a quantitative theory of the spectrum of the next element - helium - proved impracticable.
However, Bohr's postulates - physics, which laid a strong foundation of brick in the quantum theory to this day are the most important observations and conclusions.In particular, it was possible to construct a theory of absorption and emission of light that make on the basis of classical physics just unreal.
Bohr's postulates allowed to breathe new life into the classical mechanics.To this day they remain undisputed in the framework of quantum mechanics.