The elements Boron, Silicon, Germanium, Arsenic, Antimony, and Tellurium belong to which category?

• A. Noble Gases
• B. Metals
• C. Nonmetals
• D. Metalloids

Answer: (D)

Metalloids are elements with properties between metals and nonmetals, sitting along the staircase boundary on the periodic table. The elements Boron, Silicon, Germanium, Arsenic, Antimony, and Tellurium lie right on that boundary, so they share that mixed character. Their hallmark is semiconducting behavior: they conduct electricity better than nonmetals but not as well as metals, and their conductivity can be tuned by temperature or by adding small amounts of impurities. This blend of traits—brittle solids with some metallic character and reliable, controllable conductivity—fits the metalloid category. Noble gases are inert and gaseous, which doesn’t match these elements’ solid, semi-metallic behavior. Ordinary metals are typically malleable and highly conductive, unlike these borderline elements. Nonmetals lack the semiconducting properties and mixed character these elements exhibit.