Argon (Ar), an element with the atomic number 18, is classified as a nonmetal. This colorless, odorless element exists as a gas at standard temperature and pressure, exhibiting extreme chemical inertness. Argon is the most abundant noble gas found in Earth’s atmosphere, representing approximately 0.93% of the air we breathe. Its classification as a nonmetal stems from its physical and chemical characteristics, which are the opposite of metallic properties.
How Elements Are Classified
Elements on the periodic table are sorted into three categories: metals, nonmetals, and metalloids. This classification is based on their shared physical and chemical properties. Metals are good conductors of heat and electricity, possess a shiny luster, and are both malleable and ductile. Most metals exist as solids at room temperature.
Nonmetals are poor conductors of heat and electricity, lack metallic luster, and are often brittle in a solid state. Metalloids represent an intermediate category, displaying properties of both metals and nonmetals, such as having a metallic appearance but acting as partial conductors. This makes metalloids useful as semiconductors, and the classification system allows scientists to predict an element’s behavior.
The Nonmetallic Properties of Argon
Argon’s physical state and conductive nature place it within the nonmetal group. Unlike metals, which are mostly solids, Argon is a monatomic gas under normal conditions, only condensing to a liquid at extremely low temperatures. It lacks the reflective, shiny surface known as metallic luster.
Argon is a poor conductor of both heat and electricity. Its atoms do not easily release the free-moving electrons necessary to facilitate the flow of current or thermal energy, which is a hallmark of metallic elements. If solidified, Argon would be brittle rather than malleable or ductile, aligning with the properties of other nonmetals.
Argon’s Role as a Noble Gas
Argon is categorized as a noble gas due to its position in Group 18 of the periodic table. Noble gases are defined by having a complete valence shell of eight electrons, which results in high stability. This full outer shell means Argon is unreactive and does not readily form chemical bonds with other elements, a behavior common to nonmetals.
This chemical inertness is why Argon is used widely in industry. It serves as a protective shielding gas during arc welding to prevent oxidation of the metal. Argon is also used to fill incandescent light bulbs, preventing the tungsten filament from rapidly burning out and extending the bulb’s lifespan.