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  2. Ammonium - Wikipedia

    en.wikipedia.org/wiki/Ammonium

    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 ...

  3. Onium ion - Wikipedia

    en.wikipedia.org/wiki/Onium_ion

    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 .

  4. VSEPR theory - Wikipedia

    en.wikipedia.org/wiki/VSEPR_theory

    The lone pairs on transition metal atoms are usually stereochemically inactive, meaning that their presence does not change the molecular geometry. For example, the hexaaquo complexes M(H 2 O) 6 are all octahedral for M = V 3+ , Mn 3+ , Co 3+ , Ni 2+ and Zn 2+ , despite the fact that the electronic configurations of the central metal ion are d ...

  5. Chemical structure - Wikipedia

    en.wikipedia.org/wiki/Chemical_structure

    Theories of chemical structure were first developed by August Kekulé, Archibald Scott Couper, and Aleksandr Butlerov, among others, from about 1858. [4] These theories were first to state that chemical compounds are not a random cluster of atoms and functional groups, but rather had a definite order defined by the valency of the atoms composing the molecule, giving the molecules a three ...

  6. Anammox - Wikipedia

    en.wikipedia.org/wiki/Anammox

    Anammox, an abbreviation for "anaerobic ammonium oxidation", is a globally important microbial process of the nitrogen cycle [1] that takes place in many natural environments. The bacteria mediating this process were identified in 1999, and were a great surprise for the scientific community. [ 2 ]

  7. Ammonia - Wikipedia

    en.wikipedia.org/wiki/Ammonia

    The salts produced by the action of ammonia on acids are known as the ammonium salts and all contain the ammonium ion ([NH 4] +). [38] Although ammonia is well known as a weak base, it can also act as an extremely weak acid. It is a protic substance and is capable of formation of amides (which contain the NH − 2 ion).

  8. Ionic radius - Wikipedia

    en.wikipedia.org/wiki/Ionic_radius

    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.

  9. List of chemistry mnemonics - Wikipedia

    en.wikipedia.org/wiki/List_of_chemistry_mnemonics

    An atom (or ion) whose oxidation number increases in a redox reaction is said to be oxidized (and is called a reducing agent). It is accomplished by loss of one or more electrons. The atom whose oxidation number decreases gains (receives) one or more electrons and is said to be reduced. This relation can be remembered by the following mnemonics.