Chemistry: What’s a Chromophore?

Chemistry
One online definition of chromophore is "an atom or group whose presence is responsible for the color of a compound." Although one may think of a chromophore that includes a metal atom such as copper, nickel, or cobalt, in organic chemistry a chromophore is more likely to consist of a collection of carbon-carbon multiple bonds, perhaps with modifying features. It is the organic variety we discuss in this article. Multiple Bonds Most organic compounds incorporate one or more of three carbon-to-carbon bond varieties: single bonds, double bonds, triple bonds. When drawing a basic organic compound, these are usually represented by: C–C, C=C, and C≡C, respectively. Although such notations are quite useful, they afford little information concerning bond nature and behavior. Bond Hybridization The best working hypothesis for bonding between atoms…
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The Difference Between Alkanes, Alkenes, and Alkynes

Chemistry, Education
[caption id="attachment_16044" align="alignright" width="440"] An acetylene (ethyne) torch.[/caption] Alkanes, alkenes, and alkynes are made up of carbon and hydrogen. The carbon atoms in each exhibit a valency of four.  Though these three hydrocarbon varieties are similar, there is a difference in bonding. We illustrate this with the simplest example: ethane vs. ethene vs. ethyne. Common and Scientific Names Common names are names given to many compounds, but they may mislead the uninitiated. For instance, the scientific names of alkenes contain the suffix –en(e) as part of their name. But acetylene is not an alkene. It is an alkyne. The scientific names of alkynes contains the suffix –yne. Acetylene is scientifically named ethyne. Yet, it nomenclature is not the only difference between alkanes, alkenes, and alkynes. Alkanes Alkanes are completely saturated…
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Acetylene and Acetylides

Chemistry
Acetylene and acetylides are easy to make and simple to understand. Acetylene (ethyne) is one of the tiniest organic compounds. Its formula is C₂H₂. The two carbon atoms share a triple bond. Its structure is HC≡CH. Acetylides are produced from acetylene by replacing one hydrogen atom. Acetylene is a useful fuel. Despite this, acetylene can form acetylides that are extremely dangerous, explosive! Making Acetylene Making the gas is simple. Mixing calcium carbide with water makes acetylene. CaC₂ + 2 H₂O → Ca(OH)₂ + C₂H₂↑ Calcium Carbide Where does calcium carbide come from? Lime and coke are combined at temperatures ranging from 2000 to 2100 degrees C in an electric arc furnace. CaO + 3C → CaC₂ + CO↑ [caption id="attachment_16272" align="alignright" width="280"] Calcium carbide[/caption] Triple Bond What is the origin of…
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