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Diagram of measurements: D is the slant distance; S is the horizontal distance; Δh is the vertical distance. Tacheometry ( / ˌ t æ k i ˈ ɒ m ɪ t r i / ; from Greek for "quick measure") is a system of rapid surveying , by which the horizontal and vertical positions of points on the Earth's surface relative to one another are determined ...
In chemistry, hexahydro-1,3,5-triazine is a class of heterocyclic compounds with the formula (CH 2 NR) 3. Known as aldehyde ammonias, these compounds characteristically crystallize with water . They are reduced derivatives of 1,3,5- triazine , which have the formula (CHN) 3 , a family of aromatic heterocycles.
Hydroxide is a diatomic anion with chemical formula OH −.It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge.
Lewis structure of a water molecule. Lewis structures – also called Lewis dot formulas, Lewis dot structures, electron dot structures, or Lewis electron dot structures (LEDs) – are diagrams that show the bonding between atoms of a molecule, as well as the lone pairs of electrons that may exist in the molecule.
This glossary of chemistry terms is a list of terms and definitions relevant to chemistry, including chemical laws, diagrams and formulae, laboratory tools, glassware, and equipment. Chemistry is a physical science concerned with the composition, structure, and properties of matter , as well as the changes it undergoes during chemical reactions ...
A tachometer that can indicate up to 7000 RPM (left) A tachometer (revolution-counter, tach, rev-counter, RPM gauge) is an instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine. [1] The device usually displays the revolutions per minute (RPM) on a calibrated analogue dial, but digital displays are ...
Valence shell electron pair repulsion (VSEPR) theory (/ ˈ v ɛ s p ər, v ə ˈ s ɛ p ər / VESP-ər, [1]: 410 və-SEP-ər [2]) is a model used in chemistry to predict the geometry of individual molecules from the number of electron pairs surrounding their central atoms. [3]
In some important cases (topological index calculation etc.) the following classical definition is sufficient: a molecular graph is a connected, undirected graph which admits a one-to-one correspondence with the structural formula of a chemical compound in which the vertices of the graph correspond to atoms of the molecule and edges of the ...