1 Lab 3 Emission Spectroscopy Remote Version Laboratory Exercise 3Virtual Experience EMISSION SPECTROSCOPY: YOUR TASKS FOR COMPLETING THIS LAB: 1.Read the Objectives and the Introduction (pages 1 - 3). 2.Complete Activity A in the Procedure (page 3). 3.Complete the Pre-lab (page 8). 4.Save the completed Pre-lab and submit it to Canvas* before your in-person lab period (October 5th - 9th). (page 8) with file name: Lab_3_Pre_Lab_Your Name_Your_Section_Number.doc (or pdf) 5.Complete the Activities in the Procedure (pages 4 - 7) 6.Complete the Data, Observations and Calculations section (pages 9 - 14). 7.Complete the Post-lab questions (pages 13 - 15). 8.Submit the Lab Report (Pages 9-15) to the Lab 3 Remote Assignment on Canvas* before your next in-person lab period (October 12th - 16th). Lab_3_Report_Your Name_Your_Section_Number.doc (or pdf) *You may print out these pages and handwrite your input or you may type it in. If handwritten, you will need to scan the pages and create a file to be submitted. If input is typed, save this document as a word or pdf file. Either way, do your work in a different color and save the file as: Lab 3 (Pre_Lab or Report)_Your Name_Your_Section_Number.doc (or pdf) OBJECTIVES -To view emission spectra of different substances and appreciate the uniqueness of each line spectra. -To measure the wavelength of each line in the hydrogen emission spectrum and associate those emissions with possible electron transitions.
2 Lab 3 Emission Spectroscopy Remote Version INTRODUCTION Spectroscopy is the study of substances through their emitted or absorbed electromagnetic radiation. Using spectroscopy, you can “look” inside an atom and gain an understanding of atomic structure and validate (or refute) existing hypotheses about atomic structure. In emission spectroscopy when an atom in a high-energy state transitions to a low-energy state it releases energy. When that energy (light) is passed through a slit and then a prism the light is separated into its component wavelengths; the series of resulting lines, known as a line spectrum, is characteristic of the element. Figure 1 shows the splitting of light emitted from hydrogen atoms in an excited state (due to the electrical current running through the gas discharge tube) into its component wavelengths and the resulting line spectrum; only those emissions in the visible region of the electromagnetic (EM) spectrum are shown in Figure 1. Figure 1 Source: Each line in the spectrum corresponds to an electronic transition. According to the Bohr model of the atom, when an electron transitions from a higher energy level to a lower one, the energy of the emitted light (photon) is equal to the energy of the spacing between the two levels involved in the transition as shown in Figure 2: Figure 2 The energy of the emitted photon is equal to the energy difference between the two levels:Ephoton= En,high– En,lowThis is must be so in accordance with the conservation of energy.