Group 15 Elements
The 15th group of the periodic table
consists of nitrogen, phosphorus, arsenic, antimony and bismuth. These elements
are known as pnicogens and their
compounds as pniconides.
Nitrogen and Phosphorous are non-metals, arsenic and
antimony are metalloids while bismuth is a metal.
Occurrence of group 15 elements
Molecular nitrogen comprises 78% by
volume of the atmosphere. In the earth’s crust, it occurs as sodium nitrate,
NaNO3 (called
Chile saltpetre) and potassium nitrate, KNO3 (Indian saltpetre). It is found
in the form of proteins in plants and animals.
Phosphorus occurs in minerals of the apatite family,
Ca9(PO4)6.CaX2 (X
= F, Cl or OH) (e.g., fluorapatite Ca9(PO4)6.CaF2) which are the main components of
phosphate rocks. Phosphorus is an essential constituent of animal and plant
matter. It is present in bones as well as in living cells. Phosphoproteins are
present in milk
and eggs.
Arsenic, antimony and bismuth are
found mainly as sulphide minerals.
Electronic
configuration
The valence shell electronic configuration of
all the elements of this group is ns2np3.
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