Atomic Spectra - Lab Report

Atomic Spectra Pre-Lab Questions 1. On the Periodic Table, elements with similar properties are placed together in the same column/group because their atoms have the same number of electrons. 2. What is an atom's electronic structure? The electronic structure of an atom describes the energies and arrangement of electrons around the atom. 3. Electromagnetic radiation carries energy through space and is also known as radiant energy.. 4. All el electromagnetic ectromagnetic radiation travels at the same speed (in a va vacuum) cuum) which is 3.00x108 m/s,, also known as the speed of light . 5. For the following diagram of a wave, what do these letters re represent? present? A- Wavelength. The distance between corresponding points on adjacent waves. B- Amplitude. The height of the wave. 6. Fill in the blanks with the words short or long. A wave with a high frequency has a shorter wavelength. A wave with a low frequency has a longer wavelength. 7. The product of the frequency o f radiation and its wavelength can be expresse expressed d in an equation. State that equation, what each symbo symboll rep represents, resents, and the units for each. The product of frequency and wavelength is the speed of light. c = λv c- the speed of light, 3.00x108 m/s v- frequency, s-1 or Hz λ- wavelength, m,cm,mi,km, etc. 8. Make a sketch of the Electromagnetic Spectrum. (See Fig. 6.4) 9. State the frequency of your favorite radio stat station ion in Hertz Hertz.. The Spot 95.7 MHz x 106 = 9.57 x 107 Hz. Data Table • Colors of Flames of Salt Solutions Salt LiCl NaCl CaCl2 SrCl2 BaCl2 KCl CuCl2 • • Color Red Teal Blue Violet Color to eye Red Orange Orange Orange/Magenta Yellow Light pink Green Colors of Emission Tubes Gas Color to eye Neon Red Hydrogen Orange Helium Orange Nitrogen Orange/Magenta Spectral Lines Calculated Data for Hydrogen Spectral Lines a (cm) 100 100 100 100 b (cm) 76.1 47.5 42.2 38.7 d (cm) 1 x 10-4 1 x 10-4 1 x 10-4 1 x 10-4 Wavelength (cm) 6.07x10-5 4.29x10-5 3.88x10-5 3.61x10-5 Wavelength (m) Frequency (Hz) 6.07x10-7 4.94x1014 -7 4.29x10 6.99x1014 3.88x10-7 7.73x1014 3.61x10-7 8.31x1014 Energy (J) 3.27x10-19 4.63x10-19 5.12x10-19 5.51 x10-19 Calculations and d nno o t due to chlorine. 1. Cite evidence that the color observed is due to the metallic element an The color observed is due to the metallic element, since chlorine was common in all the salts compounds. Therefore, the only thing that effected the color of the flame was the different metals we used. 2. Explain the use of flame tests to identify unknowns. The flame test is used to visually determine the identity of unknowns based on the color of the salt. the salt turns the flame of a Bunsen burner to different colors depends on the substance. Therefore, we can determine the substance identity by looking on the color change of the flame. 3. Given the following known wavelen wavelengths gths for hydrogen, compare your experimental answer by % difference (show your work for at least o one ne of the calculations for credit): Line Known Value Experimental Value % Difference red blue-green blue violet 6.653 x 10-5 4.861 x 10-5 4.340 x 10-5 4.102 x 10-5 6.07x10-5 4.29x10-5 3.88x10-5 3.61x10-5 9% 12 % 11 % 12 % 4. The visib visible le hydrogen transition corresponds to hydrogen electrons falling form higher levels down to the second level. Usi Using ng Ry Rydberg’s dberg’s fo formula, rmula, 11// = 1.1 x 105 cm-1 (1/nf 2 - 1/ni2), determine the valu valuee of ni for the transition responsible for the s pectral lines yo you u see. Note: if your experimental wavelength values differ from the known values by more than a 1 or 2%, use th thee known values for wavelength given above. Line red blue-green blue violet Known Values of Wavelengths (cm) 6.653 x 10-5 4.861 x 10-5 4.340 x 10-5 4.102 x 10-5 ni 3 4 5 6 5. In whi which ch part of the electromagnetic spectrum would you expect to find the spectral line for the transition of an electron from the n = 6 to the n = 1 energy level in a hydrogen atom? By looking on the electromagnetic spectrum, the transition of an electron from the n = 6 to the n = 1 energy level in a hydrogen atom would be in the Infrared part since the wavelength is x10-4.