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Formula unit. In chemistry, a formula unit is the smallest unit of a non-molecular substance, such as an ionic compound, covalent network solid, or metal. [ 1][ 2] It can also refer to the chemical formula for that unit. Those structures do not consist of discrete molecules, and so for them, the term formula unit is used. In contrast, the terms ...
In chemistry, an activated complex represents a collection of intermediate structures in a chemical reaction when bonds are breaking and forming. The activated complex is an arrangement of atoms in an arbitrary region near the saddle point of a potential energy surface. [ 1] The region represents not one defined state, but a range of unstable ...
Atom economy. Atom economy ( atom efficiency/percentage) is the conversion efficiency of a chemical process in terms of all atoms involved and the desired products produced. The simplest definition was introduced by Barry Trost in 1991 and is equal to the ratio between the mass of desired product to the total mass of reactants, expressed as a ...
Formal charge. In chemistry, a formal charge ( F.C. or q* ), in the covalent view of chemical bonding, is the hypothetical charge assigned to an atom in a molecule, assuming that electrons in all chemical bonds are shared equally between atoms, regardless of relative electronegativity. [ 1][ 2] In simple terms, formal charge is the difference ...
Specific activity. In the context of radioactivity, activity or total activity (symbol A) is a physical quantity defined as the number of radioactive transformations per second that occur in a particular radionuclide. [ 1] The unit of activity is the becquerel (symbol Bq), which is defined equivalent to reciprocal seconds (symbol s -1 ).
Graph of number of coupons, n vs the expected number of trials (i.e., time) needed to collect them all, E (T ) In probability theory, the coupon collector's problem refers to mathematical analysis of "collect all coupons and win" contests.
An example is the condensed molecular/chemical formula for ethanol, which is CH 3 −CH 2 −OH or CH 3 CH 2 OH. However, even a condensed chemical formula is necessarily limited in its ability to show complex bonding relationships between atoms, especially atoms that have bonds to four or more different substituents.
In finance, a day count convention determines how interest accrues over time for a variety of investments, including bonds, notes, loans, mortgages, medium-term notes, swaps, and forward rate agreements (FRAs). This determines the number of days between two coupon payments, thus calculating the amount transferred on payment dates and also the ...