Bohr’s Postulate of Quantisation

What Is Bohr’s Model Of An Atom?

In 1915, Neils Bohr put forth his Bohr atomic model. Changes to Rutherford’s nuclear model were responsible for this. The atomic atom model is introduced by Rutherford, who explains that electrons surround the nucleus (positively charged).

According to the Bohr Model of an atom, electrons can only move within the atomic structure model’s fixed orbitals (shells). In addition, the energy level of each orbit (cover) is constant. Essentially, Rutherford defined the atom’s nucleus, and Bohr transformed that model into electrons and their respective energy levels.

 According to Bohr’s model, electrons revolve around a small, positively charged nucleus in a series of orbits. For Bohr, distance from the core significantly affected electron energy, while proximity to the nucleus had a much smaller effect.

Postulates Of Bohr’s Model Of An Atom

The nucleus of an atom is responsible for nearly all of its mass (This is thought to be the preservation of the Rutherford model).

 Electrons rotate the nucleus in specific circular channels that are allowed.

 h is the Planck’s constant, and the angular momentum of the electron is a integer multiple of h / 2π Since L = mvr = nh / 2π if m is the mass and v is the electron velocity within the permissible radius, we get n = 1, 2, 3, etc.

n is the number of lines in the orbital angular force. In quantum theory, the number n is the real quantum number.  

 No light or energy is lost when electrons move in orbits of atom. Transverse or non-radioactive movement of electrons observed in the orbits. To overcome Rutherford’s limitations in conveying the stability of the atom, Bohr used this method. The associated power grows in direct proportion to the size of the nucleus’ energy level range. K, L, M, and N are the various energy levels, referred to as ask, l, m, and n.

 As a rule, electrons remain in the same place or orbit. The term “ground state” refers to this type of atomic state. The electron absorbed some when it reaches a higher energy level. Energy is released when an electron jumps to lower energy level.

 De Broglie’s Justification of Bohr’s Assumption

As proposed by Bohr in 1927, De Broglie came up with an explanation for why the angular momentum might be quantized in the manner Bohr assumed it was. De Broglie realized that if you use the wavelength associated with the electron, and assume that an integral number of wavelengths must fit in the circumference of an orbit, you get the same quantized angular momentum that Bohr did.

De-Broglie electron waves travel in circular orbits with n = 4, 2Rn = 4x, where x is the wavelength of the De-Broglie electron wave.  

 This quantum condition proposed by Bohr governs the electron’s angular momentum. The hydrogen atom’s discrete orbits and energy levels can be explained using this equation. The de-Broglie hypothesis presented Bohr’s second postulate on the quantization of electron angular momentum. Only resonant standing waves can persist in electron orbits and energy states because of the electron’s wave nature.

 Limitations Of Bohr’s Model Of An Atom

• Bohr’s model has numerous flaws. Some examples are provided below:

Using the Bohr model, hydrogenic atoms can be represented. Like helium, it cannot expand beyond the expansion of two atomic electrons. An attempt was made to analyze hydrogenic atoms with more than one electron in the Bohr model lines, but no success was found. Each electron serves as a link between the positive nucleus and every other electron in the system.

• It fails to explain why elliptical orbits should be preferred over circular ones.

• As shown in the hydrogen spectrum, these lines aren’t just one single line but rather a set of distinct and slightly differing frequencies. Hydrogen spectrum structures that defy Bohr’s predictions are a mystery to us.

• No information is provided by Bohr’s theory regarding the stiffness of various spectral lines. On the other hand, Bohr’s theory only predicts the wave patterns of these lines.

• There are no spectral lines in the magnetic field (Zeeman effect) nor in the electric field (Stark effect).
• When a well-placed nucleus and an electron come together, they form the Bohr model. Electrical power from multiple electron atoms is not included in this method.

Bohr theory is applicable:

 A single electron-only H-like species, such as Li2+, can be described by Bohr’s theoretical framework. In the case of hydrogen-like atoms, the Bohr model can be applied (single electron system). There is only one electron in Li2+ and H-atoms. There are 2, 0 electrons in each of He and He2+.

Conclusion

 Electrons achieve a precise rotation of the nucleus in the circular path. In the same orbit, the strength of the electrons remains constant. Once the path is taken, it will not release or absorb energy. Horizontal regions are also referred to as vertical areas’.

Bohr proposed that the electron’s angular force be restricted. This means that electrons can only move in the direction of Plack’s constant (h/2π), which is the angular force of the electron.

To put it another way, we can say that the relationship between the mass of an electron and the velocity of its orbit can be expressed in terms of the integer number n, which is the electron’s mass.

Only when n = 1, 2, 3,… n can have stable conditions or energy levels. We refer to this as the Bohr state of affairs.