Au is the abbreviation of Latin Aurum, which is the symbol of chemical elements of gold. Gold is a chemical element with atomic number 79, belonging to transition metal. It is located in the 1 1 family of the 6th period of the periodic table of elements. Gold is a yellow precious metal with good electrical and thermal conductivity. It exists in the form of pure metal in nature and is one of the earliest metals discovered and used by human beings on earth. Gold is widely used in jewelry, currency, electronic equipment and other fields. Gold is chemically stable and is not easy to be oxidized or corroded. It is also an important investment and trade commodity.