2.05

Electron Arrangement and EMR – Virtual Lab

Line Spectra

Part I: Flame Tests

• How do atoms produce light?– When energy is added to an atom, the electrons

will absorb the energy and move to higher energy levels.

– The electrons are now in the “excited state”• Unstable, temporary situation

– Consequently electrons will ‘fall’ back down to a lower energy level, dispersing the added energy in the form of Electromagnetic Radiation (light)

– The difference of energy will determine which color of light is emitted

• We can use the color of light to determine the locations of the electron orbitals.

• The differences in orbital location and potential energy are unique to every element.

• We can use the color produced to identify the element.

Flame Test Results

Identification of the Unknown Solutions

Lab Report: Fill in data table with the flame colors (5 points) Identify each unknown from part 1 of the lab, and briefly explain why you identified each unknown as you did. (2 points)

Element Flame Color

Barium

Calcium

Potassium

Rubidium

Sodium

Lithium

Unknown #1

Unknown #2

Part II - Spectroscopy

• Spectroscopy is the analysis of line spectra and of the way light interacts with matter

• Light passes through a narrow slit to produce a beam of light. It is then separated using a prism. Different colors of visible light appear as different lines according to their wavelengths.

• Different elements produce different line spectra. There is unique spacing between the energy levels

How spectroscopy works

Hydrogen Line Spectra

Lab report: Record the color and wavelength (nm) for each line in your data table. (5 points for entire data table)

Helium Line Spectra

Lab report: Record the color and wavelength (nm) for each line in your data table.

Sodium Line Spectra

Lab report: Record the color and wavelength (nm) for each line in your data table.

Neon Line Spectra

Lab report: Record the color and wavelength (nm) for each line in your data table.

Mercury Line Spectra

Lab report: Record the color and wavelength (nm) for each line in your data table.

Compare Spectrums

Lab Report: Describe the line spectrum of the star. Give the color and wavelength value of the five brightest lines in the spectrum. (3 points)

Conclusion

1. Explain, in your own words, why different elements produce different colors of light when heated. (5 points)

2. Why do you think that the elements had to be heated before they emit the colored light? (2 points)

3. What element do you think is the most abundant in the star that you observed in part 2? Explain your answer. (3 points)