1. Atomic Spectra
Lab 1

2. Light
If we pass light through a prism or diffraction grating, we can see the intensity as a function of wavelength.

3. Type of Spectrum
Solids, liquids, and dense gases emit light of all wavelengths, without any gaps – or a continuous spectrum

4. Thin gases emit light of only a few wavelengths - an emission or bright line spectrum.

5. If there is a source of light behind it, a thin gas will absorb light of the same wavelengths it emits
this is called an absorption or dark line spectrum.

7. Different Emission Line SpectraH He C

8. Balmer lines
each element generates its own unique set of wavelengths of emission or absorption
Balmer studied the optical spectrum of hydrogen and found a pattern in the wavelengths of its emission lines

9. Periodic Table of Elements

11. Balmer series – set of visible lines in H spectrum
For H, the wavelengths are
a simple formula reproduces these wavelengths
λ (n) = (364.5 nm * ( n2 /n2 – 4))
where n = 3, 4, 5, …..

12. other scientists found similar patterns in other portions of the electromagnetic spectrum

13. Paschen series
Paschen, in the infrared, measured lines with wavelengths
which matched the series
λ (n) = (820.5 nm * ( n2 /n2 – 9))
where n = 4, 5, 6, …..

14. Lyman series
Lyman, in the ultraviolet, a series of lines with wavelengths
corresponding to the series
λ (n) = (91.1 nm * ( n2 /n2 – 1))
where n = 2, 3, 4, …..

15. In fact, scientists soon realized that hydrogen's spectrum could be broken down into a large number of series, each of which had wavelengths obeying a formula like
Λ (n,k) = (limit) * ( n2 /n2 – k2)) where n=k+I, k+2,….
The Lyman series corresponds to k=1 with a limit of 91.1 nm, the Balmer series to k=2 with a limit of nm, and so forth