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  2. Chemistry - Wikipedia

    en.wikipedia.org/wiki/Chemistry

    Chemistry is the scientific study of the properties and behavior of matter. [1] It is a physical science within the natural sciences that studies the chemical elements that make up matter and compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during reactions with other substances.

  3. Substitution reaction - Wikipedia

    en.wikipedia.org/wiki/Substitution_reaction

    The two reactions are named according tho their rate law, with S N 1 having a first-order rate law, and S N 2 having a second-order. [2] S N 1 reaction mechanism occurring through two steps. The S N 1 mechanism has two steps. In the first step, the leaving group departs, forming a carbocation (C +). In the second step, the nucleophilic reagent ...

  4. List of unsolved problems in chemistry - Wikipedia

    en.wikipedia.org/wiki/List_of_unsolved_problems...

    This is a list of unsolved problems in chemistry. Problems in chemistry are considered unsolved when an expert in the field considers it unsolved or when several experts in the field disagree about a solution to a problem.

  5. Chemical species - Wikipedia

    en.wikipedia.org/wiki/Chemical_species

    In supramolecular chemistry, chemical species are structures created by forming or breaking bonds between molecules, such as hydrogen bonding, dipole-dipole bonds, etc. [3] These types of bonds can determine the physical property of chemical species in a liquid or solid state.

  6. Reaction mechanism - Wikipedia

    en.wikipedia.org/wiki/Reaction_mechanism

    It follows that the rate of formation of CH 4 is d[CH 4]/dt = k 2 [•CH 3][CH 3 CHO] = k 2 (k 1 / 2k 4) 1/2 [CH 3 CHO] 3/2. Thus the mechanism explains the observed rate expression, for the principal products CH 4 and CO. The exact rate law may be even more complicated, there are also minor products such as acetone (CH 3 COCH 3) and propanal ...

  7. Dimerization - Wikipedia

    en.wikipedia.org/wiki/Dimerization

    In chemistry, dimerization is the process of joining two identical or similar molecular entities by bonds. The resulting bonds can be either strong or weak. Many symmetrical chemical species are described as dimers, even when the monomer is unknown or highly unstable. [1] The term homodimer is used when the two subunits are identical (e.g.

  8. Organic reaction - Wikipedia

    en.wikipedia.org/wiki/Organic_reaction

    Organic chemistry has a strong tradition of naming a specific reaction to its inventor or inventors and a long list of so-called named reactions exists, conservatively estimated at 1000. A very old named reaction is the Claisen rearrangement (1912) and a recent named reaction is the Bingel reaction (1993).

  9. Resonance (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Resonance_(chemistry)

    Contributing structures of the carbonate ion. In chemistry, resonance, also called mesomerism, is a way of describing bonding in certain molecules or polyatomic ions by the combination of several contributing structures (or forms, [1] also variously known as resonance structures or canonical structures) into a resonance hybrid (or hybrid structure) in valence bond theory.