N2

Nitrogen \Ni`tro*gen\ (n[imac]"tr[-o]*j[e^]n), n. [L. nitrum
   natron + -gen: cf. F. nitrog[`e]ne. See {Niter}.] (Chem.)
   A colorless nonmetallic element of atomic number 7, tasteless
   and odorless, comprising four fifths of the atmosphere by
   volume in the form of molecular nitrogen ({N2}). It is
   chemically very inert in the free state, and as such is
   incapable of supporting life (hence the name {azote} still
   used by French chemists); but it forms many important
   compounds, such as ammonia, nitric acid, the cyanides, etc,
   and is a constituent of all organized living tissues, animal
   or vegetable. Symbol N. Atomic weight 14.007. It was formerly
   regarded as a permanent noncondensible gas, but was liquefied
   in 1877 by Cailletet of Paris, and Pictet of Geneva, and
   boils at -195.8 [deg] C at atmospheric pressure. Liquid
   nitrogen is used as a refrigerant to store delicate
   materials, such as bacteria, cells, and other biological
   materials.
   [1913 Webster +PJC]
    

Chromophore \Chro"mo*phore\, n. [Gr. ? color + fe`rein to bear.]
   (Chem.)
   Any chemical group or residue (as {NO2}; {N2}; or {O2}) which
   imparts some decided color to the compound of which it is an
   ingredient.
   [1913 Webster]