Nitrogen group

Group 15 of the periodic (formerly numbered as Group Ⅴ or Group ⅤA) is also known by the collective name pnictogens.^[1]

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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 most important element of this group is nitrogen (N), which in its diatomic form is the principal component of air. Other members of the group include phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi) and ununpentium (Uup) (unconfirmed).

Binary compounds of the group can be referred to collectively as pnictides. The spelling derives from the Greek πνίγειν (pnigein), to choke or stifle, which is a property of nitrogen; they are also mnemonic for the two most common members, P and N. The name pentels (from the Latin penta, five) was also used for this group at one time, stemming from the earlier group naming convention (Group VB).

These elements are also noted for their stability in compounds due to their proclivity for double and triple covalent bonds. This is the property of these elements which leads to their potential toxicity, most evident in phosphorus, arsenic and antimony. When these chemicals react with various chemicals of the body, they create strong free radicals not easily processed by the liver, where they accumulate. Paradoxically it is this strong bonding which causes nitrogen and bismuths reduced toxicity(when in molecular bonds), as these form strong bonds with other atoms which are difficult to split, creating very stable molecules. For example N₂, the diatomic form of nitrogen, is used for inert atmosphere in situations where xenon or another noble gas would be prohibitively expensive.

The nitrogen group consits of two non-metals, two metalloids, and one metal. All the elements in the group are a solid at room temperatue except for Nitrogen which is a gas at room temperature.