Radical (chemistry)

In chemistry, radicals (often refered to as free radicals) are atomic or molecular species with unpaired electrons or an otherwise open shell configuration. These unpaired electrons are usually highly reactive, so radicals are likely to take part in chemical reactions. Radicals play an important role in combustion, atmospheric chemistry, polymerization, plasma chemistry, biochemistry, and many other chemical processes. "Radical" and "Free Radical" are frequently used interchangeably, however a radical may be trapped within a solvent cage or be otherwise bound. Historically, "Radical" was used to refer to a collection of atoms that remain unchanged over the course of a reaction, however this usage is, today, uncommon. The first organic free radical (the triphenylmethyl radical) was identified by Moses Gomberg in 1900.

Diagnostics

Radical diagnostic techniques include:

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• Electron Spin Resonance

:A widely-used technique for studying free radicals, and other paramagnetic species, is electron spin resonance spectroscopy (ESR). This is alternately referred to as "electron paramagnetic resonance" (EPR) spectroscopy. It is conceptually related to nuclear magnetic resonance, though electrons resonate with higher-frequency fields at a given fixed magnetic field than do most nuclei.

Related Topics:
Electron spin resonance - Spectroscopy - Electron paramagnetic resonance - Nuclear magnetic resonance - Magnetic field

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• Nuclear magnetic resonance using a phenomenon called CIDNP
• Chemical Labelling

:Chemical labelling by quenching with free radicals, e.g. with NO or DPPH, followed by spectroscopic methods like X-ray photoelectron spectroscopy (XPS) or absorption spectroscopy, respectively.

Related Topics:
NO - DPPH - X-ray photoelectron spectroscopy - Absorption spectroscopy

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