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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. List of unsolved problems in chemistry - Wikipedia

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

    How do the spin–orbit coupling, other relativistic corrections, and inter-electron effects modify the chemistry of the trans-actinides? [1] [2] Is it possible to create a practically-useful lithium–air battery? [3]

  4. Chemical reaction - Wikipedia

    en.wikipedia.org/wiki/Chemical_reaction

    Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur. The substance (or substances) initially involved in a chemical reaction are called reactants or reagents.

  5. Addition reaction - Wikipedia

    en.wikipedia.org/wiki/Addition_reaction

    In organic chemistry, an addition reaction is an organic reaction in which two or more molecules combine to form a larger molecule called the adduct. [1] [2] An addition reaction is limited to chemical compounds that have multiple bonds. Examples include a molecule with a carbon–carbon double bond (an alkene) or a triple bond (an alkyne).

  6. Döbereiner's triads - Wikipedia

    en.wikipedia.org/wiki/Döbereiner's_triads

    By 1829, Döbereiner had found other groups of three elements (hence "triads") whose physical properties were similarly related. [2] He also noted that some quantifiable properties of elements (e.g. atomic weight and density) in a triad followed a trend whereby the value of the middle element in the triad would be exactly or nearly predicted by taking the arithmetic mean of values for that ...

  7. Cage effect - Wikipedia

    en.wikipedia.org/wiki/Cage_effect

    In polymers, the probability of a free radical pair to escape recombination in the cage is 0.1 – 0.01 and 0.3-0.8 in liquids. [5] In unimolecular chemistry, geminate recombination has first been studied in the solution phase using iodine molecules [ 10 ] and heme proteins.

  8. VSEPR theory - Wikipedia

    en.wikipedia.org/wiki/VSEPR_theory

    [1]: 410–417 In VSEPR theory, a double bond or triple bond is treated as a single bonding group. [1] The sum of the number of atoms bonded to a central atom and the number of lone pairs formed by its nonbonding valence electrons is known as the central atom's steric number.

  9. History of chemistry - Wikipedia

    en.wikipedia.org/wiki/History_of_chemistry

    The protoscience of chemistry, and alchemy, was unsuccessful in explaining the nature of matter and its transformations. However, by performing experiments and recording the results, alchemists set the stage for modern chemistry. The history of chemistry is intertwined with the history of thermodynamics, especially through the work of Willard ...