Gold is not a metalloid. The element (Au, atomic number 79) is classified as a transition metal on the periodic table. This designation is based on physical and chemical characteristics that align with metallic behavior, contrasting sharply with the intermediate nature of metalloids.
What Defines a Metalloid
Metalloids, sometimes referred to as semimetals, occupy a unique space in the periodic table because they exhibit properties intermediate between true metals and nonmetals. They serve as a transition zone, physically looking somewhat like metals, often possessing a metallic luster, but chemically behaving more like nonmetals. This dual nature is the defining characteristic for elements such as Boron (B), Silicon (Si), Germanium (Ge), Arsenic (As), Antimony (Sb), and Tellurium (Te).
A primary property of metalloids is their intermediate electrical conductivity, classifying them as semiconductors. Unlike metals, their conductivity can be precisely controlled by introducing impurities, making them indispensable in modern electronics. Their chemical reactivity is also a blend; their oxides are often amphoteric, meaning they can react with both acids and bases.
The Distinct Properties of Gold
Gold’s atomic structure firmly places it away from the metalloid classification. With 79 protons, gold is a transition metal (Group 11, Period 6). Its physical properties are those of a classic metal, exhibiting high electrical and thermal conductivity.
Gold has a high density (approximately 19.3 grams per cubic centimeter). It is the most malleable and ductile element, meaning it can be hammered into thin sheets or drawn into fine wires.
Chemically, gold is highly inert, resisting reaction with most common acids and bases. This stability, characteristic of noble metals, contrasts sharply with the variable reactivity and semiconducting nature of metalloids.
Understanding the Periodic Table Classification
The periodic table is organized based on electron configuration, which dictates the properties of each element. A diagonal line resembling a staircase serves as the traditional boundary separating metals from nonmetals.
Metals lie to the left and center of this line, while nonmetals are positioned to the right. Metalloids border the staircase line in the p-block, and their proximity gives them hybrid properties.
Gold is not found near this boundary. Instead, it resides in the central section of the periodic table known as the d-block, or the transition metals.
Gold’s d-block classification means its valence electrons occupy a d-orbital, resulting in metallic properties like high luster and excellent conductivity. D-block elements (Groups 3 through 12) are situated deep within the metal region, far from the metalloid boundary. Therefore, based on its location, gold is definitively classified as a metal, not a metalloid.