Bohr theory normal

Stark effect The splitting of lines in the spectra of atoms due to the presence of a strong electric field. It is named after the German physicist Johannes Stark (1874-1957), who discovered it in 1913. Like the normal Zeeman effect, the Stark effect can be understood in terms of the classical electron theory of Lorentz. The Stark effect for hydrogen atoms was also described by the Bohr theory of the atom. In terms of quantum mechanics, the Stark effect is described by regarding the electric field as a perturbation on the quantum states and energy levels of an atom in the absence of an electric field. This application of perturbation theory was its first use in quantum mechanics. 

Zeeman effect The splitting of atomic spectral lines by a magnetic field. This effect was found by the Dutch physicist Pieter Zeeman (1865-1943) in 1896. Some of the patterns of line splitting that be explained both by classical electron theory and the BOHR THEORY of electrons in atoms. The Zeeman splitting that can be explained in these ways is known as the normal Zeeman effect. There exist more complicated Zeeman splitting patterns that cannot be explained either by classical electron theory or the Bohr theory. This more complicated type of Zeeman effect is known as the anomalous Zeeman effect. It was subsequently realized that the anomalous Zeeman effect occurs because of electron spin and that the normal Zeeman effect occurs only for transitions between singlet states. 

Bohr orbits for an electron in the hydrogen atom. These circular and elliptical orbits were involved in the Bohr theory. They do not provide a correct de.scription of the motion of the electron in the hydrogen atom. According to the theory of quantum mechanics, which seems to be essentially correct, the electron moves about the nucleus in the hydrogen atom in roughly the way described by Bohr, but the motion in the normal state ( = 1) is not in a circle, but is radial (in and out. toward the nucleus and away from the nucleus). The most probable distance of the electron from the nucleus, according to quantum mechanics, is the same as the radius of the Bohr orbit. 

On account of the normalization the denominator will be equal to 1 the volume element is a spherical shell izr2dr. The result is the same as that of Bohr s theory, where in fact a is... 

In a magnetic field, E depends on m also, indeed the extra term mvjh occurs as an addition to the energy, exactly as in Bohr s theory. Wave mechanics, so far as we have developed it up to the present, yields only the normal Zeeman effect (as above, 2, p. 110). To the directional quantisation of Bohr s theory there corresponds here the finite number of values of m, i.e. of energy levels in the magnetic field there are in fact 2Z + 1 of these, in place of each term which occurs when there is no magnetic field. The splitting of the terms in an electric field (Stark effect) is correctly reproduced by wave mechanics, qualitatively and quantitatively. 

Today Bohr s concept of an electronic orbit is no longer tenable, but the modern quantum theory substitutes for the orbit a probability distribution, in which, in the case of the hydrogen atom, the probability is concentrated in the region where the Bohr orbit was. For a free electron (i.e., one not bound to the hydrogen nucleus), the probability distribution looks like that of a wave—a confined region of oscillations, called a wave packet. These wavelike properties are extremely difficult to observe under normal conditions because typical wavelengths of electrons are extremely short—around 10 or m. Wavelike... 

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