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Arrow pushing or electron pushing is a technique used to describe the progression of organic chemistry reaction mechanisms. [1] It was first developed by Sir Robert Robinson.In using arrow pushing, "curved arrows" or "curly arrows" are drawn on the structural formulae of reactants in a chemical equation to show the reaction mechanism.
Newton's laws are often stated in terms of point or particle masses, that is, bodies whose volume is negligible. This is a reasonable approximation for real bodies when the motion of internal parts can be neglected, and when the separation between bodies is much larger than the size of each.
Each time a dislocation moves through a crystal, part of the crystal shifts by one lattice point along a plane, relative to the rest of the crystal. The plane that separates the shifted and unshifted regions along which the movement takes place is the slip plane. To allow for this movement, all ionic bonds along the plane must be broken. If all ...
[Also known as rectilinear motion] Reciprocal motion; Brownian motion – the random movement of very small particles; Circular motion; Rotatory motion – a motion about a fixed point. (e.g. Ferris wheel). Curvilinear motion – It is defined as the motion along a curved path that may be planar or in three dimensions.
A [1,5] shift involves the shift of 1 substituent (hydride, alkyl, or aryl) down 5 atoms of a π system. Hydrogen has been shown to shift in both cyclic and open-chain compounds at temperatures at or above 200 ˚C. [4] These reactions are predicted to proceed suprafacially, via a Hückel-topology transition state. [1,5] hydride shift in a ...
The manner in which they diffuse is important as it may dictate the kinetics of movement, temperature dependence, and overall mobility of surface species, among other parameters. The following is a summary of the most important of these processes: [12] Hopping or jumping is conceptually the most basic mechanism for diffusion of adatoms. In this ...
This pathway runs along the reaction coordinate, which is a parametric curve that follows the pathway of the reaction and indicates its progress; thus, energy profiles are also called reaction coordinate diagrams.
The movement of mobile dislocations allow atoms to slide over each other at low stress levels and is known as glide or slip. The movement of dislocations may be enhanced or hindered by the presence of other elements within the crystal and over time, these elements may diffuse to the dislocation forming a Cottrell atmosphere. The pinning and ...