Nitrogen (N, atomic number 7) is a nonmetal element. It is the most abundant element in Earth’s atmosphere, making up approximately 78% of the air we breathe. This colorless and odorless gas is fundamental to life and industry. Its chemical behavior and physical characteristics align it with the nonmetallic elements.
Defining Nonmetals: The Characteristic Properties
Nonmetals are distinguished by a set of physical and chemical properties that stand in contrast to those of metals. Physically, nonmetals are poor conductors of both heat and electricity. Nitrogen, existing as a gas at standard temperature and pressure, exhibits this lack of conductivity. Solid nonmetals often lack metallic luster and are brittle, not being malleable or ductile like metals.
Chemically, nonmetals tend to have high electronegativity, meaning they strongly attract electrons when forming bonds with other atoms. Nitrogen’s electronegativity of 3.04 on the Pauling scale places it among the highest of the elements. This high electron affinity drives nonmetals like nitrogen to primarily form covalent bonds, sharing electron pairs to achieve stability, rather than forming positive ions (cations) like metals.
Nitrogen’s Place on the Periodic Table
Nitrogen’s position on the periodic table provides a clear structural explanation for its nonmetallic behavior. It is located in Group 15 (sometimes called the pnictogens) and Period 2, placing it firmly on the right side of the table.
With an atomic number of 7, the neutral nitrogen atom possesses five valence electrons in its outermost shell. Because atoms strive to achieve a stable octet of eight valence electrons, nitrogen’s five electrons mean it is much easier to gain or share three electrons than to lose all five. This electronic configuration is the direct cause of its high electronegativity and its preference for forming covalent compounds. Elements higher up and further to the right on the table, such as nitrogen, exhibit stronger nonmetallic character due to a smaller atomic radius and a greater pull on electrons.
Elemental Forms and Common Compounds
In its elemental state, nitrogen exists as diatomic nitrogen gas (\(\text{N}_2\)). This molecule is characterized by an extremely strong triple covalent bond between the two nitrogen atoms. This triple bond requires a large amount of energy to break, making \(\text{N}_2\) a relatively inert gas under normal conditions. This inert quality makes it useful as a non-reactive filler gas in many industrial applications, such as preventing oxidation in stored foods or creating controlled atmospheres.
Nitrogen forms numerous compounds that are vital to life, including ammonia (\(\text{NH}_3\)) and various nitrogen oxides. Nitrogen is a constituent of all amino acids, which are the building blocks of proteins, and it is a fundamental component of the nucleic acids DNA and RNA. The movement of nitrogen through the atmosphere, soil, and living organisms is described by the nitrogen cycle.