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bronzeprairie-dog351Lv1

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Certain elements emit light of a specific wavelength when they are burned. Historically, chemists used such emission wavelengths to determine whether specific elements were present in a sample. Characteristic wavelengths for some of the elements are given in the following table:
(a) Determine which elements emit radiation in the visible part of the spectrum. (b) Which element emits photons of highest energy? Of lowest energy? (c) When burned, a sample of an unknown substance is found to emit light of frequency 9.23 × 10¹⁴ s^{- 1}. Which of these elements is probably in the sample?

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Trinidad TremblayLv2

21 May 2020

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Procedure for Part 1 1.Using the TV Specs, observe and record atomic emission spectra from H lamp. 2.Sketch the atomic emission spectrum of H. Include color and wavelength.3.Repeat step 1 with the Hg lamp.4.Sketch the atomic emission spectrum of Hg. Include color and wavelength.5.Repeat step 1 with the Helamp.6.Sketch the atomic emission spectrum of He. Include color and wavelength.

Procedure for Part 2

4.Conduct a full spectrum analysis of a colored solution.a.Fill a cuvette Â¾ full with the colored solution and place it in the spectrometer. Align the cuvette so that the clear sides are facing the light source of the spectrometer.b.Click . A full spectrum graph of the colored solution will be displayed.c.Once signal has stabilized, click d.Examine the graph, noting the peak or peaks of very high absorbance or other distinguishing features. Compare the color of the solution with the wavelength associated with that color. Use the ârainbowâ chart drawn above.e.To Save your graph, select Store Latest Run from the Experiment menu.

Post lab question

1. Briefly explain why the gas discharge tube glows when the high voltage is

applied. Why does the gas not glow when the voltage is turned off.

2. When you look directly at the gas discharge tube through the grating, do you see the color

of a single wavelength of light or a blend of wavelengths?

3.Other than our blending of colors of different wavelengths emitted from a single source,

what is another limitation of using our eyes to detect electromagnetic radiation?

4. Explain how the emission phenomenon can be used

to find out what elements are present in an unknown sample.

5. What is a continuous spectra? What type of source creates a continuous spectra?

6. Explain why atomic emission spectra are not continuous.

7. How many lines are there in the Hg line spectra? How many

did you see? What might be the reason that these two answers are different?

8. Why do atoms absorb and emit light of the same frequency? In other words, why donât

atoms absorb light at one set of frequencies and emit light at another set of frequencies?

9. Why does the atomic emission spectrum vary from element to element? Explain how

atomic structure influences the spectrum.

10. In part 2, does the wavelength of maximum absorbance (ie: the color that corresponds to

the wavelength) for each solution correspond to the color of the solution that you âseeâ?

Describe why or why not? (For instance, for the red solution, was the highest absorbance

measured at the red wavelength and describe why or why not?)

plz help me answer as much as possible thanks

When the spectrum of light from the Sun is examined in high resolution in an experiment similar to that illustrated in Figure 6.9, dark lines are evident. These are called Fraunhofer lines, after the scientist who studied them extensively in the early nineteenth century. Altogether, about 25,000 lines have been identified in the solar spectrum between 2950 Å and 10,000 Å. The Fraunhofer lines are attributed to absorption of certain wavelengths of the Sun’s “white” light by gaseous elements in the Sun’s atmosphere. (a) Describe the process that causes absorption of specific wavelengths of light from the solar spectrum. (b) To determine which Fraunhofer lines belong to a given element, say, neon, what experiments could a scientist conduct here on Earth?

magentacricket434

Use a ruler to calibrate the spectral limits in the figure above. In other words, what are the right and left limits in nm, and what is the equation that converts distance on this page in cm to spectral units of nm? This âcalibrationâ will help you with the next item.

Use the NIST Atomic Spectral Database to assign the three bright spectral lines in the hydrogen spectrum.

Abstract This physical chemistry laboratory exercise will have students work with provided emission spectra for several elements and data collected on the NIST Atomic Spectral Database. First, students will develop a method for calculating what wavelengths of visible light are associated with the most intense spectral lines in the provided visible emission spectra. Then, the NIST Atomic Spectral Database will be accessed in order to identify select properties associated with the four most intense spectral lines. Introduction The emission process can be described in two general parts. Initially, energy is absorbed by an atom, and its electrons can be moved into higher energy (excited) states from their ground state The excitedrelectrons then "relax" and drop back to their ground state. Energy lost during an electron's retaxation process is emitted as a photon. Recall that the energy of a photon is photon upper E lower Where Ephoton is the energy of the photon that is emitted when the emitter drops from an upper energy state to a lower energy state, h is Planck's constant, c is the speed of light, and v is the wavenumber. Remember that the length units should match for c and v This is a good time to revisit a few concepts. Atoms and molecules possess discrete energy levels their energy levels are quantized and not continuous. Using eq 7.1, it is possible to determine the energy associated with a specific excited state to ground state transition if we can determine the wavelength of emitted light. Also keep in mind that there are selection rules that limit the type of transitions we can expect to observe. All of these points are reflected in an elemental or ionic emission spectrum. The visible light spectrum falls within a fairly narrow range of wavelengths, from approximately 400 to 700 nm. Even so, discrete spectral lines are seen in each element's visible light emission spectrum. Each (take some time to reflect on why that would be), each element also has a unique emission spectrum. This provides a diagnostic tool for determining the composition of a sample. As an example, the elements present in celestial objects can be determined by the light that they produce line represents one possible transition. Since each element has unique energy levels Some of the transitions observed in this lab exercise involve d-orbitals. As such, a discussion regarding d-orbitals and related selection rules is necessary at this point. The first goal is to determine which character table should be used. Start by observing the shape and relative orientations of the d-orbitals. Refer to Figure 1 below

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