Nitrogen lies in the fifteenth group and second period of the periodic table. The seven electrons in an atom of nitrogen give it its atomic number, seven. The symbol 'N' represents nitrogen, which is a nonmetallic element having no color, odor or taste. More than known 10 isotopes of nitrogen exist with known half-lives. It makes up around 78 percent of the earth's atmosphere by volume. Liquefaction of air, followed by separation and distillation produces commercial nitrogen.
The energy orbitals of nitrogen contain seven electrons. A nitrogen atom requires two orbitals: s and p, to hold its electrons. Filling of the orbitals takes place according to the Aufbau principle, Pauli's exclusion principle and Hund's rule of maximum multiplicity. The first 1s orbital in the nitrogen atom has two electrons followed by 2s orbital with two electrons; completely occupying both the orbitals. The third energy orbital, 2p, has three electrons which fill it half..
Liquid nitrogen often acts as a preservative for substances like sperm, eggs and embryos. Nitrogen can create inert environment needed in welding. Sometimes, nitrogen also preserves documents, foods and chemicals to prevent them from oxidizing or reacting with air or water. Commercial production of ammonia by Haber's process by using nitrogen as a base is an industrial application of the element. Fertilizers contain nitrogen as a vital ingredient needed for crop growth. Nitric acid production process utilizes nitrogen as a raw material. Nitrogen is a vital ingredient of compound used in making gunpowder, like nitroglycerin and trinitrotoluene commonly known as TNT.
Liquid nitrogen can cause severe frostbite to exposed bare skin. Some compound of nitrogen, like nitrates and nitrites can cause several health effects like reactions with blood and decreased functioning of the thyroid gland. Due to extensive use of fertilizers, concentration of nitrates and nitrites increase in the soil, thus the amount of nitrogen in food, groundwater and surface water is greatly increased. Cattle food having excess nitrogen can cause the oxygen transport of the blood to decrease and nitrates can form nitro-amines in the animal stomach and intestines that are dangerously carcinogenic compounds.