Search results
Results from the WOW.Com Content Network
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 ...
Heteropolymetalates: K 5 [IMo 6 O 24]·nH 2 O Ag 7 [PV 12 O 36]·nH 2 O (NH 4) 4 [NiMo 6 O 24 H 6]·5H 2 O K 3 [CrMo 6 O 24 H 6]·nH 2 O (NH 4) 8 [CeMo 12 O 42]·8H 2 O. In chemistry, the heteropolymetalates are a subset of the polyoxometalates, which consist of three or more transition metal oxyanions linked together by shared oxygen atoms to form a closed 3-dimensional molecular framework.
Nonterminal symbols are those symbols that can be replaced. They may also be called simply syntactic variables. A formal grammar includes a start symbol, a designated member of the set of nonterminals from which all the strings in the language may be derived by successive applications of the production rules.
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 ...
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.
The practice also continues with tritium compounds. When the name of the solvent is given, a lowercase d is sometimes used. For example, d 6-benzene or C 6 D 6 can be used instead of C 6 [2 H 6]. [14] The symbols for isotopes of elements other than hydrogen and radon are no longer used in the scientific community.
Moreover, a hydrogen atom in a molecule can form a second, albeit weaker, bond with an atom or group of atoms in another molecule. Such bonding, "helps give snowflakes their hexagonal symmetry, binds DNA into a double helix ; shapes the three-dimensional forms of proteins ; and even raises water's boiling point high enough to make a decent cup ...