Heteroatom
In chemistry, a heteroatom (Template:Ety) is, strictly, any atom that is not carbon or hydrogen.<ref>Template:Cite book</ref>
Organic chemistry
[edit]In practice, the term is mainly used more specifically to indicate that non-carbon atoms have replaced carbon in the backbone of the molecular structure. Typical heteroatoms are nitrogen (N), oxygen (O), sulfur (S), phosphorus (P), chlorine (Cl), bromine (Br), and iodine (I),<ref>Template:Cite journal</ref><ref>Template:Cite encyclopedia</ref> as well as the metals lithium (Li) and magnesium (Mg).
Proteins
[edit]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.<ref name="pdbformat">Template:Cite web</ref>
Zeolites
[edit]In the context of zeolites, the term heteroatom refers to partial isomorphous substitution of the typical framework atoms (silicon, aluminium, and phosphorus) by other elements such as beryllium, vanadium, and chromium.<ref>Template:Cite book</ref> The goal is usually to adjust properties of the material (e.g., Lewis acidity) to optimize the material for a certain application (e.g., catalysis).