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A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.

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Questions regarding fuels and the properties of fuels, like calorific value, octane number, mechanism of combustion, etc., should use this tag.
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For questions about the concept of aromaticity. Do not use for reactions of aromatic compounds.
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biopolymers consisting primarily of polycondensated amino acids.
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For questions about the atomic radius - a measure of the size of an atom, usually the mean or typical distance from the center of the nucleus to the boundary of the surrounding "cloud" of electrons.
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For questions about reduction reactions in organic chemistry, where a molecule of interest is reduced. Do not use for questions on general redox concepts.
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Also known as cis/trans isomerism, configurational isomerism, or E/Z isomerism when referring to alkenes.
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Chemical processes and theories being used in practical and experimental applications.
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for questions about phenols, their synthesis, analysis, properties and more. Do not use the 'alcohols' tag for phenols due to the differences between the two classes.
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For questions regarding the chemical processes or chemicals involved in distinguishable smells
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For questions about conformational isomerism. Use this tag alongside [stereochemistry].
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Questions about the assumptions, equations, and properties of gases derived from kinetic theory. For questions pertaining to rates of reactions, please use the kinetics tag instead.
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Questions discussing explosive nature of chemicals. Also, consider using the safety tag.
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The adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface.
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For questions regarding chemicals and chemical processes that act on and interact within environmental systems.
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The systematic discussion of molecular symmetry is known as group theory. Group theory is a systematic way of describing the symmetry of molecules using concepts/rules borrowed from mathematics. This…
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macromolecular biological catalysts that alter the rate of a reaction. Use this tag for question regarding enzyme kinetics, classification and action.
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For questions about the synthesis, properties, and reactions of organic compounds containing the -NO2 group i.e. nitro-compounds.
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For questions involving selectivity as to where a functional group reacts.
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the process of design, synthesis, and testing of molecules (drugs) for the treatment of infection and disease. The medicinal-chemistry tag should be applied to all question…
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Questions about any process which makes water more acceptable for an end use.
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For questions about the process of distillation. For the distillation process used in metal refining, also use the [metallurgy] tag.
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a type of angular momentum which is intrinsic to atomic and sub-atomic particles. Electrons in orbitals can be either spin paired or spin unpaired which influences the magnetic properties of t…
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Questions about compounds that lower the surface tension (or interfacial tension) between two liquids or between a liquid and a solid.
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Questions about elements of group 18 (group 0 in old notation) of the periodic table and their compounds, created despite the low reactivity of these elements.
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For questions about alloys.
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For questions concerning crystalline structures and their properties.
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for questions about amino acids, both natural and non-natural ones. It should only be applied to questions about the monomers. For peptides and proteins, use the proteins tag instead.
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Chemical reactions that occur in the atmosphere of Earth and other planets. Relevant reactions include both those that take place only in the gas-phase, in the solid or liquid phases of aerosols or a…
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Chemistry-in-fiction covers all chemistry that can be seen in TV series, films and can be read in books, etc. which does not necessarily need to be based on proper scientific backgrounds.
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on E1, E2, E1cb, or any other type of elimination reaction.
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Electromagnetic radiation (EM radiation, EMR, or light) is a form of energy released by electromagnetic processes. In physics, all EMR is referred to as light, but colloquially light often refers excl…
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For questions relating to the dynamics and processes that occur within and interactions between the nuclei of atoms.
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For questions related to dissolving and subsequently precipitating as substance. The purpose may be for purifying, creating polymorphs, or other reasons.
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For questions about oxidation reactions in organic chemistry, where a molecule of interest is oxidised. Do not use for questions on general redox concepts.
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For questions about formal charge in any molecule. Do not confuse with [oxidation-state].
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an allotrope of oxygen with the general formula O3. It is hence also known as trioxygen. This tag should be applied to questions, that are specifically about its structure, properties, and us…