The Electronic Structure of Atoms in the Environment

The Electronic Structure of Atoms in Environmental/Green Chemistry and Sustainability

When a person thinks of a light bulb, the first image that comes to mind is that of an incandescent light bulb.

The incandescent light bulb makes light by heating a metal filament wire, contained inside a glass bulb, to a high temperature until it glows. You may also think of Thomas Edison who’s light bulb invention was not the first, but remarkable the most effective.

The compact fluorescent lamp (also referred to as CFL bulbs) is a fluorescent lamp designed to replace the incandescent lamp. The main difference between incandescent lighting bulbs and fluorescent lighting bulbs is in the process of stimulating the atoms.

How do they work?

CFLs produce light in a different way then incandescent bulbs. In a CFL bulb, an electric current is driven through a glass tube containing argon gas and a small amount of mercury vapor. “This generates invisible ultraviolet light that excites a fluorescent coating called phosphor (uses a mixture of three phosphors) on the inside of the tube, which then emits visible light.” (1)

The selling points for CFLs are that they use less electricity, reduce pollution, and last longer. The Negative side is that these bulbs cost more. There is also the fact that they contain a small amount of mercury. Being that there are billions of CFLs in use worldwide, this represents a definite source of mercury contamination unless CFLs are recycled and the mercury in them are recovered. (2)

Fluorescent light bulbs utilize a chemical reaction to excite atoms. The interaction of an inert gas (argon), a liquid metal (mercury), and phosphorus participate in the reaction necessary to make visible light.

Argon, going by the abbreviated symbol Ar, is the 18th element on the periodic chart. It is one of the noble gases with an electron configuration of [Ne]3s23p6. Argon works well in the CFL reaction because it is an inert gas. It is a completely stable gas and does not see to gain or lose electrons.

Mercury

CFLs contain a small amount of mercury sealed in the glass tubing. An average amount of 4 milligrams is contained in one CFL. Mercury is an essential part of CFLs because it allows the bulb to be an efficient light source. It contains two electrons in its valence shell with the element having an electron configuration of [Xe]6s24f145d10.

Wavelength of light that CFLs give off:

When a powerful light source like the sun passes through a prism, you would be able to see a continuous visible spectrum displaying all wavelengths. The visible spectrum is typically classified as being from 390-750nm. CFls are designed to provide illumination. A larger percentage of the light emitted from CFLs is specific to the visible part of the spectrum (approximately 400-700nm in wavelength). (3)

From ChemPRIME: 5.0: Prelude to Electronic Structure

References

1. (online) http://www.energystar.gov/

2. Wagner, T.P. (2011) Compact Fluorescent Lights and the Impact of Convenience and knowledge on household Recycling rates, Waste Management volume 31 issue 6 pgs 1300-1306.

3. (online) http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/HomeBusinessandEntertainment/ucm116400.htm

Contributors and Attributions

• Ed Vitz (Kutztown University), John W. Moore (UW-Madison), Justin Shorb (Hope College), Xavier Prat-Resina (University of Minnesota Rochester), Tim Wendorff, and Adam Hahn.