1. Spectra and Energy Levels in Atoms
© D Hoult 2011

2. The light from a normal filament lamp gives a

3. The light from a normal filament lamp gives a continuous spectrum

4. The light from a normal filament lamp gives a continuous spectrum

5. The light from a normal filament lamp gives a continuous spectrum
Light from gas discharge lamps contains only certain wavelengths. Many of the colours of light are absent from the spectrum

6. The light from a normal filament lamp gives a continuous spectrum
Light from gas discharge lamps contains only certain wavelengths. Many of the colours of light are absent from the spectrum
Spectra like this are called

7. The light from a normal filament lamp gives a continuous spectrum
Light from gas discharge lamps contains only certain wavelengths. Many of the colours of light are absent from the spectrum
Spectra like this are called line spectra

8. The light from a normal filament lamp gives a continuous spectrum
Light from gas discharge lamps contains only certain wavelengths. Many of the colours of light are absent from the spectrum
Spectra like this are called line spectra

9. Balmer measured the wavelengths of visible light emitted by hydrogen atoms. He found that they could be described by the following formula (now called the Balmer series)

10. Balmer measured the wavelengths of visible light emitted by hydrogen atoms. He found that they could be described by the following formula (now called the Balmer series)

11. To explain these observations, Bohr made the following suggestions:

12. To explain these observations, Bohr made the following suggestions:
1. Electrons in atoms can only exist

13. To explain these observations, Bohr made the following suggestions:
1. Electrons in atoms can only exist with certain “allowed” energies

14. To explain these observations, Bohr made the following suggestions:
1. Electrons in atoms can only exist with certain “allowed” energies
2. An electron can be excited from one energy level to another by

15. To explain these observations, Bohr made the following suggestions:
1. Electrons in atoms can only exist with certain “allowed” energies
2. An electron can be excited from one energy level to another by a collision with another particle or by

16. To explain these observations, Bohr made the following suggestions:
1. Electrons in atoms can only exist with certain “allowed” energies
2. An electron can be excited from one energy level to another by a collision with another particle or by absorbing a quantum of electro-magnetic radiation

17. 3. When an electron falls from one energy level to a lower level,

18. 3. When an electron falls from one energy level to a lower level, it emits one quantum of electro-magnetic radiation

19. 3. When an electron falls from one energy level to a lower level, it emits one quantum of electro-magnetic radiation
4. The energy possessed by the quantum is equal to

20. 3. When an electron falls from one energy level to a lower level, it emits one quantum of electro-magnetic radiation
4. The energy possessed by the quantum is equal to the difference between the initial and final energy levels of the electron

21. The lowest energy is called the

22. The lowest energy is called the “ground state”

23. Energy level diagrams

38. quanta in the UV region of the spectrum

39. quanta in the UV region of the spectrum

40. quanta in the UV region of the spectrum
the Lyman series

42. quanta in the IR region of the spectrum

43. quanta in the IR region of the spectrum

44. quanta in the IR region of the spectrum
the Paschen series