Nitrogen 7 N 14.00674(7) Nitrogen is used in Cryogenic Nitrogen Pressure Tanks. Properties Symbol Name Atomic Number Atomic Weight Group Number N nitrogen 7 14.00674(7) 15 Description Standard State: gas at 298 K Color: colorless Nitrogen makes up 78% of the earth's atmosphere, by volume.  When nitrogen is a liquid, it is colorless and odorless making it look similar to water.  Nitrogen is used primary as a coolant; most commonly used in rockets and as a refrigerant in food storage.