Atomic Spectra

Question 1

Atomic spectrum

Answer 1

Divided into two:
1.absorption spectrum
2.emission spectrum

Question 2

Emission spectrum

Answer 2

Divided into 3:
1. line /discrete spectrum=> hydrogen
2. band spectrum => molecules
3. continuous spectrum => black body

Question 3

Spectroscopy

Answer 3

The branch of physics which deals with the investigation of wavelength and intensities of electromagnetic radiations emitted or absorbed by atoms is called spectroscopy

Question 4

Atomic spectrum

Answer 4

Spectrum of radiation due to transition between energy levels in an atom.
Note: the fact that the spectrum of any element contains wavelength that exhibits.

Question 5

Line/ discrete spectrum

Answer 5

Spectrum which consist of discrete lines corresponding to single wavelength of imitate radiation is called line spectrum.
For example: atomic spectra of hydrogen atom.

Question 6

Spectral series (line spectrum)

Answer 6

The spectrum of an element contains certain wavelength that show definite regularities into certain groups called spectral series.
The results obtained by balmer were expressed in 1896 by J.R. Rydberg:
1\λ = R(1/p^2 - 1/n^2)
• R=> Rydberg constant -> value is 1.0974×10^7m^-1

Question 7

Bohr’s model of hydrogen

Answer 7

To explain the empirical results obtained by rydburg , neils bohr in 1913 formulated a model of hydrogen atom utilizing classical physics and Planck’s quantum theory.

Question 8

Postulate of Bohr’s model of hydrogen

Answer 8

1. Electron moving around the nucleus in a circular orbit without radiating these orbits are cointized stationary state of atom.
2. Only those orbits are allowed in which angular momentum of electron is integral multiple of h/ 2π
   mvr=nh
3. When an electron jumps from a higher energy state “En” to “EP” a photon of energy hf is emitted such that
   En - Ep = hf

Question 9

De- Broglie interpretation of bohr postulate