Gold is one of the transition metals, a group of elements found in the center of the periodic table in Rows 4, 5, and 6 between Groups 2 and 13. Its atomic number is 79, its atomic mass is 196.9665, and its chemical symbol is Au.

Properties

Gold is a fairly soft metal with a beautiful golden color. It is unusually ductile and malleable and can be hammered into very thin sheets with a thickness of only 0.00001 in (0.00025 cm). Gold foil of this thickness is used to make lettering on window signs. Gold has a melting point of 1,947°F (1,064°C), a boiling point of about 5,070°F (2,800°C), and a density of 19.3 grams per cubic centimeter. Gold is an excellent conductor of electricity and has a high optical reflectivity.

Generally speaking, gold is not very reactive. It does not react with oxygen, the halogens, or most acids at room temperature. This property...