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Lever rule. In chemistry, the lever rule is a formula used to determine the mole fraction ( xi) or the mass fraction ( wi) of each phase of a binary equilibrium phase diagram. It can be used to determine the fraction of liquid and solid phases for a given binary composition and temperature that is between the liquidus and solidus line.
Hund's rules. In atomic physics and quantum chemistry, Hund's rules refers to a set of rules that German physicist Friedrich Hund formulated around 1925, which are used to determine the term symbol that corresponds to the ground state of a multi-electron atom. The first rule is especially important in chemistry, where it is often referred to ...
Second rule: the electrostatic valence rule. For a given cation, Pauling defined [2] the electrostatic bond strength to each coordinated anion as , where z is the cation charge and ν is the cation coordination number. A stable ionic structure is arranged to preserve local electroneutrality, so that the sum of the strengths of the electrostatic ...
Slater's rules. In quantum chemistry, Slater's rules provide numerical values for the effective nuclear charge in a many-electron atom. Each electron is said to experience less than the actual nuclear charge, because of shielding or screening by the other electrons. For each electron in an atom, Slater's rules provide a value for the screening ...
Slater–Condon rules. Within computational chemistry, the Slater–Condon rules express integrals of one- and two-body operators over wavefunctions constructed as Slater determinants of orthonormal orbitals in terms of the individual orbitals. In doing so, the original integrals involving N -electron wavefunctions are reduced to sums over ...
Therefore, measurements at two wavelengths yields two equations in two unknowns and will suffice to determine the amount concentrations c 1 and c 2 as long as the molar attenuation coefficients of the two components, ε 1 and ε 2 are known at both wavelengths. This two system equation can be solved using Cramer's rule.
He illustrates that F and Φ obey the formulas F ∝ 1 / R^2 sinh^2(r/R) and Φ ∝ coth(r/R), where R and r represent the curvature radius and the distance from the focal point, respectively. [11] The concept of the dimensionality of space, first proposed by Immanuel Kant, is an ongoing topic of debate in relation to the inverse-square law. [12]
Scientists. v. t. e. Wick's theorem is a method of reducing high- order derivatives to a combinatorics problem. [ 1] It is named after Italian physicist Gian-Carlo Wick. [ 2] It is used extensively in quantum field theory to reduce arbitrary products of creation and annihilation operators to sums of products of pairs of these operators.