Search results
Results from the WOW.Com Content Network
It can also be used with highly specific meanings in specialised contexts. In the description of protein structure, in particular in the Protein Data Bank file format, a heteroatom record (HETATM) describes an atom as belonging to a small molecule cofactor rather than being part of a biopolymer chain.
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 ...
Also acid ionization constant or acidity constant. A quantitative measure of the strength of an acid in solution expressed as an equilibrium constant for a chemical dissociation reaction in the context of acid-base reactions. It is often given as its base-10 cologarithm, p K a. acid–base extraction A chemical reaction in which chemical species are separated from other acids and bases. acid ...
In chemistry, cyanide (from Greek kyanos 'dark blue') is a chemical compound that contains a C≡N functional group. This group, known as the cyano group, consists of a carbon atom triple-bonded to a nitrogen atom. [1] In inorganic cyanides, the cyanide group is present as the cyanide anion − C≡N. This anion is extremely poisonous.
In quantum chemistry, the quantum theory of atoms in molecules (QTAIM), sometimes referred to as atoms in molecules (AIM), is a model of molecular and condensed matter electronic systems (such as crystals) in which the principal objects of molecular structure - atoms and bonds - are natural expressions of a system's observable electron density distribution function.
The common atom that connects the two (or sometimes three) rings is called the spiro atom. [2]: SP-0 In carbocyclic spiro compounds like spiro[5.5]undecane, the spiro-atom is a quaternary carbon , and as the -ane ending implies, these are the types of molecules to which the name spirane was first applied (though it is now used general of all ...
A 3D model of ethyne (), the simplest alkyneIn organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carbon—carbon triple bond. [1] The simplest acyclic alkynes with only one triple bond and no other functional groups form a homologous series with the general chemical formula C n H 2n−2.
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 .