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The hydrogen atoms in the ammonium ion can be substituted with an alkyl group or some other organic group to form a substituted ammonium ion (IUPAC nomenclature: aminium ion). Depending on the number of organic groups, the ammonium cation is called a primary, secondary, tertiary, or quaternary. Except the quaternary ammonium cations, the ...
Molecular geometry is the three-dimensional arrangement of the atoms that constitute a molecule. It includes the general shape of the molecule as well as bond lengths , bond angles , torsional angles and any other geometrical parameters that determine the position of each atom.
In chemistry, an onium ion is a cation formally obtained by the protonation of mononuclear parent hydride of a pnictogen (group 15 of the periodic table), chalcogen (group 16), or halogen (group 17). The oldest-known onium ion, and the namesake for the class, is ammonium , NH + 4 , the protonated derivative of ammonia , NH 3 .
Linear triatomic molecules owe their geometry to their sp or sp 3 d hybridised central atoms. Well-known linear triatomic molecules include carbon dioxide (CO 2 ) and hydrogen cyanide (HCN). Xenon difluoride (XeF 2 ) is one of the rare examples of a linear triatomic molecule possessing non-bonded pairs of electrons on the central atom.
A simple example of a polyatomic ion is the hydroxide ion, which consists of one oxygen atom and one hydrogen atom, jointly carrying a net charge of −1; its chemical formula is O H −. In contrast, an ammonium ion consists of one nitrogen atom and four hydrogen atoms, with a charge of +1; its chemical formula is N H + 4.
There are additional names used for ions with multiple charges. For example, an ion with a −2 charge is known as a dianion and an ion with a +2 charge is known as a dication. A zwitterion is a neutral molecule with positive and negative charges at different locations within that molecule. [17]
Ionic radius, r ion, is the radius of a monatomic ion in an ionic crystal structure. Although neither atoms nor ions have sharp boundaries, they are treated as if they were hard spheres with radii such that the sum of ionic radii of the cation and anion gives the distance between the ions in a crystal lattice.
Compounds which are isoelectronic usually have similar chemical structures. For example, methane, CH 4, and the ammonium ion, NH 4 +, are isoelectric and are isostructural as both have a tetrahedral structure. The C-H and N-H bond lengths are different and crystal structures are completely different because the ammonium ion only occurs in salts.