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In chemistry a donor number (DN) is a quantitative measure of Lewis basicity. A donor number is defined as the negative enthalpy value for the 1:1 adduct formation between a Lewis base and the standard Lewis acid SbCl 5 ( antimony pentachloride ), in dilute solution in the noncoordinating solvent 1,2-dichloroethane with a zero DN.
This is a list of scientific journals in chemistry and its various subfields. For journals mainly about materials science, see List of materials science journals. A
Once this is determined, all one needs to do is take the total value of Δ f H, subtract the Δ f H caused by the C−(C) 2 (H) 2 group(s), and then divide that number by two (due to two C−(C)(H) 3 groups), obtaining the value of the C−(C)(H) 3 group. From the knowledge of these two groups, Benson moved forward obtain and list functional ...
In number theory, a deficient number or defective number is a positive integer n for which the sum of divisors of n is less than 2n. Equivalently, it is a number for which the sum of proper divisors (or aliquot sum) is less than n. For example, the proper divisors of 8 are 1, 2, and 4, and their sum is less than 8, so 8 is deficient.
HLB scale showing classification of surfactant function. The hydrophilic–lipophilic balance (HLB) of a surfactant is a measure of its degree of hydrophilicity or lipophilicity, determined by calculating percentages of molecular weights for the hydrophilic and lipophilic portions of the surfactant molecule, as described by Griffin in 1949 [1] [2] and 1954. [3]
For hydrocarbons, the DBE (or IHD) tells us the number of rings and/or extra bonds in a non-saturated structure, which equals the number of hydrogen pairs that are required to make the structure saturated, simply because joining two elements to form a ring or adding one extra bond (e.g., a single bond changed to a double bond) in a structure reduces the need for two H's.
If the structure is not known, the average bond valence, S a can be calculated from the atomic valence, V, if the coordination number, N, of the atom is known using Eq. 3. = / (Eq. 3) If the coordination number is not known, a typical coordination number for the atom can be used instead.
The EcoScale metric was proposed in an article in the Beilstein Journal of Organic Chemistry in 2006 for evaluation of the effectiveness of a synthetic reaction. [11] It is characterized by simplicity and general applicability.