Atomic Spectra

Prian Jani

Heli Desai, Janni Patel

Formal Atomic Spectra Report

C125 Experimental Chemistry I

Section 18927

IUPUI

March 18th 2007

ATOMIC SPECTRA

INTRODUCTION

The study of interaction between light and an object is known as spectroscopic studies. A major factor in understanding the structure of atoms and molecules, and going as far as verifying the quantum theory is from what we have learned from Spectroscopic Studies. This experiment helps better the understanding of how to use spectroscopes and chemical changed that occurs in flame ionization. There are also 3 equations given. E=hλ , λv = c, and E = hc/λ, in which v is frequency, and λ is wavelength, this type of radiation is created by packets of energy called photons, which are measured in joules. These 3 equations help determining the data needed to compile the formal report.

EXPERIMENTAL

The first part was observation of various light sources with a hand held spectroscope. Using the hand held spectroscope the spectrum of a flashlight, the fluorescent light in the hood, and the two atomic emission lamps were all viewed.

The second part was introduction to the components of the spectroscope and how to read the Vernier scale. The power supply was plugged in and the power was switched on to illuminate the mercury lamp. After looking into the eye piece a line should have been seen, although if there was no line the telescope had to be moved in a 'arc-motion' until a line came into view. All of the lines of the mercury source were viewed. The lines should be in order of ROY G. BIV or VIB G. YOR.

The third part the calibration of the mercury lamp. The crosshairs were immediately set on a bright line of mercury. The positions of this line was recorded as represented on the Vernier scale. Using the magnifying lens the scale was read to the nearest quarter degree (0.25Ñ"), and then recorded. This procedure was repeated for; Violet (faint), Violet (bright), Blue 1 (very faint), Blue 2 (also very faint), Green, Yellow 1 and Yellow 2, each value was recorded using nearest quarter degree (0.25Ñ") as well.

The fourth part was measuring the lines in the hydrogen spectrum, the four lines of the hydrogen spectrum were found ( red, aqua, bright purple, and faint purple) using the atomic spectroscope and each angle associated with each line was recorded. A pictorial sketch was also made to help better understand the spectrum.

The fifth part included identification of metal ions by flame ionization. A Bunsen burner start up procedure was demonstrated by Andy. After starting the Bunsen burner the tubing was attached from the gas outlet to the burner. The gas was then turned on, and a match was lighten on top to start the flame, once started the match was extinguished and disposed in the space provided. The flame was adjusted to a bluish color by adjusting the amount of air given. Finally wire loops were dipped into the solutions of Ba, K, Cu, Na, and Ni, and introduced to the flame one by one. The important thing to note here was the color changed experienced in the wire loop.

DATA

The results and observations experienced from the procedure explained above can be found in data tables 1, 2, 3, and 4 as well as graphs 1 and 2. In table 1 In the analysis of Mercury The crosshairs were immediately set on a bright line of mercury. The positions of this line was recorded as represented on the Vernier scale. Using the magnifying lens the scale was read to the nearest quarter degree (0.25Ñ"), and then recorded. This procedure was repeated for; Violet (faint), Violet (bright), Blue 1 (very faint), Blue 2 (also very faint), Green, Yellow 1 and Yellow 2, each value was recorded using nearest quarter degree (0.25Ñ") as well. The best fitting line equation for the calibration curve is;

Y= -0.0724x +106.41 (1)

Table 1: Calibration of Spectroscope: Analysis of Mercury

Color of Spectral Line Wavelength (nm) Vernier o reading (to 0.25o)

* Violet 404.7 nm 76.75

* Violet 435.8 nm 74.50

Blue 1 & 2 491.6 nm 70.50

Green 546.1 nm 66.75

Yellow 1 576.9 nm 64.75

Yellow 2 579.0 nm 64.50

Graph 1: Wavelength at Vernier Degree

In table two, a table was prepared of Vernier readings ( Ñ" ), wavelengths (nm), and photon energies (J) for the four visible hydrogen spectral lines. The wavelength was calculated by the calibration curve equation.

Data Table 2: Energy (J) of Balmer Lines (Hydrogen)

Color of Line Vernier o Reading λ (nm) determined from BFL E= hc (J) λ

Red