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Prism dioptres. Prism correction is commonly specified in prism dioptres, a unit of angular measurement that is loosely related to the dioptre. Prism dioptres are represented by the Greek symbol delta (Δ) in superscript. A prism of power 1 Δ would produce 1 unit of displacement for an object held 100 units from the prism. [2]
The chemical elements are what the periodic table classifies and organises. Hydrogen is the element with atomic number 1; helium , atomic number 2; lithium , atomic number 3; and so on. Each of these names can be further abbreviated by a one- or two-letter chemical symbol ; those for hydrogen, helium, and lithium are respectively H, He, and Li ...
Esotropia is a form of strabismus in which one or both eyes turn inward. The condition can be constantly present, or occur intermittently, and can give the affected individual a "cross-eyed" appearance. [1] It is the opposite of exotropia and usually involves more severe axis deviation than esophoria. Esotropia is sometimes erroneously called ...
Square antiprism. In geometry, the square antiprism is the second in an infinite family of antiprisms formed by an even-numbered sequence of triangle sides closed by two polygon caps. It is also known as an anticube. [1] If all its faces are regular, it is a semiregular polyhedron or uniform polyhedron .
The data below tabulates standard electrode potentials ( E °), in volts relative to the standard hydrogen electrode, at: Temperature 298.15 K (25.00 °C; 77.00 °F); Effective concentration 1 mol/L for each aqueous or amalgamated (mercury-alloyed) species; Unit activity for each solvent and pure solid or liquid species; and.
A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [1] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
This page shows the electron configurations of the neutral gaseous atoms in their ground states. For each atom the subshells are given first in concise form, then with all subshells written out, followed by the number of electrons per shell. For phosphorus (element 15) as an example, the concise form is [Ne] 3s 2 3p 3.
An infrared spectroscopy correlation table (or table of infrared absorption frequencies) is a list of absorption peaks and frequencies, typically reported in wavenumber, for common types of molecular bonds and functional groups. [1] [2] In physical and analytical chemistry, infrared spectroscopy (IR spectroscopy) is a technique used to identify ...