Pnictogen

A pnictogen /ˈnɪktədʒən/ is one of the chemical elements in group 15 of the periodic table. This group is also known as the nitrogen family. It consists of the elements nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi), and perhaps the chemically uncharacterized synthetic element moscovium (Mc). In modern IUPAC notation, it is called Group 15. In CAS and the old IUPAC systems it was called Group VA and Group VB respectively (pronounced 'group five A' and 'group five B', 'V' for the Roman numeral 5). In the field of semiconductor physics, it is still usually called Group V. The 'five' ('V') in the historical names comes from the 'pentavalency' of nitrogen, reflected by the stoichiometry of compounds such as N2O5. They have also been called the pentels. The term pnictogen (or pnigogen) is derived from the Ancient Greek word πνίγειν (pnígein) meaning 'to choke', referring to the choking or stifling property of nitrogen gas. Like other groups, the members of this family show similar patterns in electron configuration, especially in the outermost shells, resulting in trends in chemical behavior. This group has the defining characteristic that all the component elements have 5 electrons in their outermost shell, that is 2 electrons in the s subshell and 3 unpaired electrons in the p subshell. They are therefore 3 electrons short of filling their outermost electron shell in their non-ionized state. The Russell-Saunders term symbol of the ground state in all elements in the group is 4S​3⁄2. The most important elements of this group are nitrogen (N), which in its diatomic form is the principal component of air, and phosphorus (P), which, like nitrogen, is essential to all known forms of life. Binary compounds of the group can be referred to collectively as pnictides. The spelling derives from the Greek verb πνίγειν (pnígein), to 'choke' or 'stifle', which is a property of molecular nitrogen in the absence of oxygen; it can also be used as a mnemonic for the two most common members, P and N. The name pentels (from Greek πέντε, pénte, five) was also used for this group at one time, stemming from the earlier group naming convention (Group VB). Pnictide compounds tend to be exotic. Various properties that some pnictides have include being diamagnetic and paramagnetic at room temperature, being transparent, and generating electricity when heated. Other pnictides include the ternary rare-earth main-group variety of pnictides. These are in the form of REaMbPnc, where M is a carbon group or boron group element and Pn is any pnictogen except nitrogen. These compounds are between ionic and covalent compounds and thus have unusual bonding properties.