The element Au on the Periodic Table is Gold, a metal recognized for its singular luster and enduring nature. The symbol “Au” is derived from the Latin word aurum, meaning “shining dawn” or “glow.” Gold has been known and prized by human civilizations since ancient times. Its inherent resistance to degradation ensured its role as a powerful cultural and monetary medium across the globe. This rare and dense element remains important in both human history and modern technology.
Gold’s Place on the Periodic Table
Gold occupies position 79 on the Periodic Table, meaning a neutral atom contains 79 protons. It is situated in Period 6 and Group 11, placing it within the family of transition metals. The standard atomic weight of Gold is approximately 196.97 atomic mass units. Its electronic configuration, [Xe] 4f¹⁴ 5d¹⁰ 6s¹, shows it possesses a single electron in its outermost shell, a feature shared with Copper and Silver in Group 11. Although elemental Gold has a full d-subshell, it is classified as a transition metal because it commonly forms ions, such as Au³⁺, which possess an incomplete d-orbital.
Defining Physical and Chemical Characteristics
Pure Gold is one of the softest and densest naturally occurring elements, with a density of 19.3 grams per cubic centimeter. It is also the most malleable and ductile of all known metals, allowing it to be hammered into extremely thin sheets or drawn into fine wire. Chemically, Gold is categorized as a noble metal, exhibiting extreme resistance to corrosion; it does not react with oxygen, sulfur, or most common acids. Its distinctive metallic yellow color is unusual among metals and results from relativistic effects on its electrons. While generally non-reactive, Gold can be dissolved by aqua regia (a mixture of nitric and hydrochloric acids) or by alkaline cyanide solutions used in mining.
Common Applications and Value
The combination of Gold’s beauty and permanence makes it a favored material in the jewelry industry, accounting for over half of global demand. Its resistance to tarnish ensures ornaments maintain their luster, while its malleability allows for intricate designs. Since pure Gold is too soft, it is typically alloyed with metals like copper or silver to increase strength, with purity measured in karats. Gold is also invaluable in high-tech industrial applications. As an excellent conductor of electricity and heat, its corrosion resistance makes it a preferred material for electrical connectors in electronics, preventing signal degradation.
Economically, Gold holds a unique position as a financial asset. It has historically served as the basis for currency systems and continues to be held as bullion by central banks and institutional investors as a hedge against inflation and economic volatility. Its high density is a practical advantage for storage, allowing large amounts of value to be concentrated in a small, easily secured space. Gold’s enduring stability and universal recognition ensure its continued role as a store of value in the global financial market.