Question

What are the inadequacies of Bohr's theory?

Short answer

Bohr's theory falls short in explaining the spectra of larger atoms, neglects the wave nature of electrons, fails to explain Zeeman and Stark Effects, contradicts Heisenberg's Uncertainty Principle and does not explain the fine structure and intensities of spectral lines.

Step-by-step solution

Inability to accurately predict spectra of large atoms

Bohr's model accurately predicts the spectra of atoms with one electron (hydrogen or ionized helium), but fails when it comes to larger atoms with more than one electron. It is unable to explain the spectrum and structure of multi-electron atoms and molecules.

Neglect of wave nature of electrons

Bohr's theory neglects the wave nature of electrons. It only considered them as particles moving in fixed paths or orbits. However, the modern quantum theory tells us that electrons exhibit both particle and wave characteristics, which is not accounted for in Bohr's model.

Lack of explanation for Zeeman Effect and Stark Effect

Bohr's model couldn't explain certain phenomena such as the Zeeman Effect (splitting of spectral lines in the presence of a magnetic field) and Stark Effect (splitting of spectral lines in the presence of an electric field). This is considered as a major limitation of his theory.

Contradiction with Heisenberg's Uncertainty Principle

Heisenberg's Uncertainty Principle states that it is impossible to simultaneously determine the exact position and momentum of a particle. However, in Bohr's model, the electrons are assumed to revolve in well-defined orbits, which means their position and momentum could be accurately measured. This contradicts the Principle of Uncertainty proposed by Heisenberg.

Failure to explain the fine structure of spectral lines

Further limitations are exposed when Bohr's theory fails to explain the fine structure of spectral lines and the intensities of spectral lines.