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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 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 ...
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 ...
Each distinct atomic number therefore corresponds to a class of atom: these classes are called the chemical elements. [5] The chemical elements are what the periodic table classifies and organizes. Hydrogen is the element with atomic number 1; helium, atomic number 2; lithium, atomic number 3; and so on.
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 ...
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.
Get ready for all of today's NYT 'Connections’ hints and answers for #551 on Friday, December 13, 2024. Today's NYT Connections puzzle for Friday, December 13, 2024 The New York Times
The f-block elements come in two series: lanthanum through ytterbium in period 6, and actinium through nobelium in period 7. All are metals. The f-orbital electrons are less active in the chemistry of the period 6 f-block elements, although they do make some contribution; [5] these are rather similar to each other. They are more active in the ...