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  2. List of unsolved problems in chemistry - Wikipedia

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

    Unsolved Problems in Nanotechnology: Chemical Processing by Self-Assembly - Matthew Tirrell - Departments of Chemical Engineering and Materials, Materials Research Laboratory, California NanoSystems Institute, University of California, Santa Barbara [No doc at link, 20 Aug 2016]

  3. List of reagents - Wikipedia

    en.wikipedia.org/wiki/List_of_reagents

    Reagents are "substances or compounds that are added to a system in order to bring about a chemical reaction or are added to see if a reaction occurs." [1] Some reagents are just a single element. However, most processes require reagents made of chemical compounds. Some of the most common ones used widely for specific reactive functions are ...

  4. Persistent, bioaccumulative and toxic substances - Wikipedia

    en.wikipedia.org/wiki/Persistent,_bio...

    Another route is the chemical travelling through the soil and ending up in ground water and in human water supply. [15] In the case that the soil is near a moving water system, the chemical could end up in large freshwater systems or the ocean, where fish are at high risk from the toxicological effects of DDT. [16]

  5. Per- and polyfluoroalkyl substances - Wikipedia

    en.wikipedia.org/wiki/Per-_and_polyfluoroalkyl...

    Different organizations use different definitions for PFAS, leading to estimates of between 8,000 and 7 million chemicals within the group. The EPA toxicity database, DSSTox, lists 14,735 unique PFAS chemical compounds. [42] [43] An early definition required that they contain at least one perfluoroalkyl moiety, −C n F 2n+1. [12]

  6. Chemical substance - Wikipedia

    en.wikipedia.org/wiki/Chemical_substance

    Some chemical substances can be combined or converted into new substances by means of chemical reactions. Chemicals that do not possess this ability are said to be inert. Pure water is an example of a chemical substance, with a constant composition of two hydrogen atoms bonded to a single oxygen atom (i.e. H 2 O).

  7. Chemical compound - Wikipedia

    en.wikipedia.org/wiki/Chemical_compound

    A chemical formula is a way of expressing information about the proportions of atoms that constitute a particular chemical compound, using chemical symbols for the chemical elements, and subscripts to indicate the number of atoms involved. For example, water is composed of two hydrogen atoms bonded to one oxygen atom: the chemical formula is H 2 O.

  8. 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 .

  9. 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.