Nitrogen
Definition and meaning of Nitrogen in chemistry.
Nitrogen is a chemical element with the symbol N and atomic number 7. It is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. Nitrogen is a common element in the universe and is estimated at about seventh in total abundance in the Milky Way and the Solar System.
In more detail
Under standard conditions, two nitrogen atoms bond to form N2, a colorless, odorless, and mostly inert diatomic gas. This diatomic nitrogen forms about 78% of Earth's atmosphere, making it the most abundant uncombined element on the planet. The strong triple bond between the atoms in N2 makes the gas highly stable, which requires significant energy to break during biological or industrial nitrogen fixation. Nitrogen occurs in all organisms, primarily in amino acids, which make up proteins, and in the nucleic acids DNA and RNA. Industrially, atmospheric nitrogen is converted into ammonia via the Haber-Bosch process, using hydrogen gas and an iron catalyst at high temperature and pressure. This ammonia serves as the precursor for synthetic fertilizers, explosives, and various chemical syntheses.
Key facts
| Field | General Chemistry |
|---|---|
| Formula | N2 |
| Molar mass | 28.014 g/mol |
| State at STP | Gas |
| Boiling point | -195.8 °C |
Liquid nitrogen is widely used as a cryogen for rapidly freezing food, preserving biological samples, and in cryosurgery to remove abnormal skin tissue.
Frequently asked questions
Why is nitrogen gas unreactive?
Nitrogen gas consists of diatomic molecules held together by a strong triple covalent bond, which requires a large amount of activation energy to break.
What is nitrogen fixation?
Nitrogen fixation is the process of converting inert atmospheric nitrogen gas into reactive compounds like ammonia or nitrates, which can be utilized by plants.