"Analyse the significance of the hydrogen spectrum in the development of the Bohr model of the atom"
Due to the individuality of the spectral lines, and since only certain wavelength's were emitted, it indicated that the electrons were changing energy levels, hence had set orbits.
"Define Bohr's postulates"
1. Electrons can revolve around certain allowed orbits - stationary states - without radiating energy.
2. When an electron falls from a higher energy level to a lower energy level, it emits energy that is quantised by the Planck relationshipm E = hf (Einstein later modified this, E = hf - Φ (work function)
3. Angular momentum is quanitsed and can only take values of nh/2π where n is the principal quantum number.
Describe how Bohr's postulates led to the development of the mathematical model to account for the existence of the hydrogen spectrum (Rydbergs formula)
The Bohr model was able to provide a physical basis for the Balmer series formula (Rydberg's equation). If you want extension look in your excel book, it has the derivation
Discuss the limitations of the Bohr model of the hydrogen atom
1. It was an ad hoc theory.
2. Did not work for multi-electron atoms.
3. Could not explain the relative intensities of the spectral lines.
4. Could not explain the hyperfine spectral lines
5. Could explain the Zeeman effect (splitting of spectral lines when placed in a magnetic field).
The equation is used to determine the wavelength of the emitted photon when an electron drops from a higher energy level to a lower energy level. It could be in a question as follows:
"Calculate the wavelength of the photon emitted in a drop from the 4th energy level to the 2nd evergy level"
In this case, n(final) = 2 and n(initial) = 4, R = Rydbergs constant which is in your data sheet, whack in the values and solve.
