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  2. Primary standard - Wikipedia

    en.wikipedia.org/wiki/Primary_standard

    1 In chemistry. 2 See also. 3 References. ... Download as PDF; Printable version; In other projects ... [1] or preparing working standards.

  3. Bohr model - Wikipedia

    en.wikipedia.org/wiki/Bohr_model

    The two additional assumptions that [1] this X-ray line came from a transition between energy levels with quantum numbers 1 and 2, and [2], that the atomic number Z when used in the formula for atoms heavier than hydrogen, should be diminished by 1, to (Z − 1) 2. Moseley wrote to Bohr, puzzled about his results, but Bohr was not able to help.

  4. Ball-and-stick model - Wikipedia

    en.wikipedia.org/wiki/Ball-and-stick_model

    A plastic ball-and-stick model of proline. In chemistry, the ball-and-stick model is a molecular model of a chemical substance which displays both the three-dimensional position of the atoms and the bonds between them. [1] The atoms are typically represented by spheres, connected by rods which represent the bonds.

  5. 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.

  6. 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]

  7. Chemometrics - Wikipedia

    en.wikipedia.org/wiki/Chemometrics

    Chemometrics is the science of extracting information from chemical systems by data-driven means. Chemometrics is inherently interdisciplinary, using methods frequently employed in core data-analytic disciplines such as multivariate statistics, applied mathematics, and computer science, in order to address problems in chemistry, biochemistry, medicine, biology and chemical engineering.

  8. Space-filling model - Wikipedia

    en.wikipedia.org/wiki/Space-filling_model

    A space-filling model of n-octane, the straight chain (normal) hydrocarbon composed of 8 carbons and 18 hydrogens, formulae: CH 3 CH 2 (CH 2) 4 CH 2 CH 3 or C 8 H 18.Note, the representative shown is of a single conformational "pose" of a population of molecules, which, because of low Gibbs energy barriers to rotation about its carbon-carbon bonds (giving the carbon "chain" great flexibility ...

  9. Fractionation - Wikipedia

    en.wikipedia.org/wiki/Fractionation

    [1] [2] Fractions are collected based on differences in a specific property of the individual components. A common trait in fractionations is the need to find an optimum between the amount of fractions collected and the desired purity in each fraction. Fractionation makes it possible to isolate more than two components in a mixture in a single run.