Helium is a familiar element. Elements exhibit a wide array of characteristics, from physical appearance to chemical reactivity. Scientists categorize these fundamental building blocks of matter based on their distinct properties, which helps organize the diverse behaviors observed across the periodic table.
Understanding Elemental Categories
Elements are broadly classified into three main categories: metals, nonmetals, and metalloids, each possessing unique sets of properties. Metals typically exhibit a shiny, lustrous appearance and are excellent conductors of both heat and electricity. They are also known for being malleable, meaning they can be pounded into thin sheets, and ductile, allowing them to be drawn into wires. Most metals exist as solids at room temperature and are generally found on the left and central parts of the periodic table.
Nonmetals generally appear dull and are poor conductors of heat and electricity. Many nonmetals are gases at room temperature, though some can be liquids or brittle solids. They are not malleable or ductile and tend to have lower melting and boiling points compared to metals. Nonmetals are predominantly located on the right side of the periodic table.
Metalloids, also known as semimetals, display properties intermediate between those of metals and nonmetals. These elements can possess a metallic luster but are often brittle solids and are used as semiconductors due to their moderate conductivity. They are found along the diagonal “staircase” line that separates metals from nonmetals on the periodic table.
Helium’s Place Among Elements
Helium is definitively classified as a nonmetal. It exists as a colorless, odorless, and tasteless gas at room temperature, a common state for many nonmetals. Unlike metals, helium does not conduct heat or electricity well. It also lacks the shiny, reflective luster typical of metals and cannot be hammered into shapes or drawn into wires.
Helium’s position on the periodic table also supports its classification. It is found in Group 18, which is the noble gas group, on the far right side of the periodic table. Elements in this group consistently exhibit nonmetallic behaviors, such as chemical inertness. Therefore, based on its physical and chemical properties, helium clearly falls into the nonmetal category.
Helium’s Unique Characteristics and Applications
Helium’s classification as a noble gas, a type of nonmetal, is a consequence of its electron configuration. It possesses a full outer electron shell, making it exceptionally stable and chemically inert. This means helium does not readily react with other elements.
Helium’s extremely low density makes it the second lightest element after hydrogen. This low density accounts for its use as a lifting gas in balloons and airships.
Liquid helium has the lowest boiling point of any known substance, at approximately -268.9 °C (-452 °F). This extremely low boiling point makes it useful in cryogenic applications, such as cooling the superconducting magnets in Magnetic Resonance Imaging (MRI) machines. Helium’s inertness and low density also make it useful in specialized applications like providing an inert atmosphere for welding metals and for creating breathable gas mixtures for deep-sea diving, where its low solubility in the bloodstream helps prevent decompression sickness.