Nitrogen, symbolized as N with an atomic number of 7, is definitively classified as a nonmetal. It is the lightest member of Group 15 on the periodic table, often called the pnictogens. Its nonmetallic nature is evident from its position on the right side of the periodic table, where elements generally exhibit nonmetallic characteristics.
Defining Metals, Nonmetals, and Semimetals
Metals form the largest group and are typically characterized by a shiny luster, high density, and the ability to conduct both heat and electricity effectively. These materials are also malleable, meaning they can be hammered into thin sheets, and ductile, allowing them to be drawn into wires. Chemically, metals tend to lose electrons easily, forming positive ions in reactions.
Nonmetals generally lack these physical attributes, often appearing dull and being brittle if solid at room temperature. They function as poor conductors of heat and electricity, acting as insulators. In chemical interactions, nonmetals usually gain or share electrons, resulting in high electronegativity.
Semimetals, also known as metalloids, possess properties intermediate between the two main groups. They are found along the zigzag line separating metals from nonmetals on the periodic table. They often have a metallic appearance but are brittle solids, notable for their electrical conductivity, which falls between that of a conductor and an insulator, making them semiconductors.
Nitrogen’s Chemical and Physical Properties
Nitrogen’s physical state at standard temperature and pressure aligns with nonmetals. It exists as a colorless, odorless diatomic gas (\(\text{N}_2\)), a trait common among nonmetals. This is a sharp contrast to metals, most of which are dense, lustrous solids at room temperature.
Nitrogen demonstrates zero electrical conductivity, functioning as an insulator rather than a conductor. Chemically, Nitrogen is highly electronegative, second only to oxygen and fluorine in its period, giving it a strong tendency to gain or share electrons. This preference results in the formation of covalent bonds, such as the triple bond found in its molecular form, \(\text{N}_2\).
The formation of this triple bond makes molecular nitrogen very stable and generally unreactive under normal conditions, often described as inert. When nitrogen reacts, it typically forms compounds through covalent bonding. When reacting with metals, it can form the nitride anion (\(\text{N}^{3-}\)), which is characteristic of nonmetal behavior. Nitrogen’s high ionization energies make the formation of simple positive ions unfavorable.
Practical Occurrence and Uses
Nitrogen makes up approximately 78% of Earth’s atmosphere as the diatomic gas \(\text{N}_2\). This vast atmospheric reservoir is the primary source for commercial and industrial processes. Its relatively inert gaseous nature allows it to serve as a blanket gas where oxygen would cause deterioration or combustion.
The element is necessary for all life on Earth, forming the structural backbone of biological molecules such as amino acids, proteins, and nucleic acids (DNA and RNA). This necessity is sustained through the nitrogen cycle, where atmospheric nitrogen is converted into usable forms by microorganisms and cycled through the biosphere.
Industrially, nitrogen’s properties are exploited in various ways:
- Liquid nitrogen is used for cryopreservation and quick-freezing food due to its low boiling point (approximately \(-196^{\circ}\text{C}\)).
- A significant portion of commercially produced nitrogen is used to manufacture ammonia, which is then converted into fertilizers and nitric acid.
- Nitrogen gas is widely used as an inert atmosphere in food packaging to prevent spoilage and oxidation.