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  2. List of unsolved problems in chemistry - Wikipedia

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

    Protein folding problem: Is it possible to predict the secondary, tertiary and quaternary structure of a polypeptide sequence based solely on the sequence and environmental information? Inverse protein-folding problem: Is it possible to design a polypeptide sequence which will adopt a given structure under certain environmental conditions?

  3. How to Solve It - Wikipedia

    en.wikipedia.org/wiki/How_to_Solve_It

    First, you have to understand the problem. [2] After understanding, make a plan. [3] Carry out the plan. [4] Look back on your work. [5] How could it be better? If this technique fails, Pólya advises: [6] "If you cannot solve the proposed problem, try to solve first some related problem. Could you imagine a more accessible related problem?"

  4. Bredt's rule - Wikipedia

    en.wikipedia.org/wiki/Bredt's_rule

    In organic chemistry, an anti-Bredt molecule is a bridged molecule with a double bond at the bridgehead. Bredt's rule is the empirical observation that such molecules only form in large ring systems. For example, two of the following norbornene isomers violate Bredt's rule, and are too unstable to prepare: Bridgehead atoms violating Bredt's ...

  5. Bond order - Wikipedia

    en.wikipedia.org/wiki/Bond_order

    In chemistry, bond order is a formal measure of the multiplicity of a covalent bond between two atoms. As introduced by Gerhard Herzberg, [1] building off of work by R. S. Mulliken and Friedrich Hund, bond order is defined as the difference between the numbers of electron pairs in bonding and antibonding molecular orbitals.

  6. Benson group increment theory - Wikipedia

    en.wikipedia.org/wiki/Benson_group_increment_theory

    These approximations account for the atomic, bond, and group contributions to heat capacity (C p), enthalpy (ΔH°), and entropy (ΔS°). The most important of these approximations to the group-increment theory is the second-order approximation, because this approximation "leads to the direct method of writing the properties of a compound as ...

  7. Par yield - Wikipedia

    en.wikipedia.org/wiki/Par_yield

    Par yield is based on the assumption that the security in question has a price equal to par value. [5] When the price is assumed to be par value ($100 in the equation below) and the coupon stream and maturity date are already known, the equation below can be solved for par yield.

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  9. Strain (chemistry) - Wikipedia

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

    There are two different ways to put both of the bonds the central in n-pentane into a gauche conformation, one of which is 3 kcal mol −1 higher in energy than the other. [1] When the two methyl-substituted bonds are rotated from anti to gauche in opposite directions, the molecule assumes a cyclopentane-like conformation where the two terminal ...