1, the natural properties of silver
Silver, chemical symbol Ag, atomic number 47, relative atomic mass 107.870, melting point 960.8℃, boiling point 22 10℃, density 10.50 g/cm3 (20℃), heat of fusion1/kloc-. Silver is soft, flexible and malleable, second only to gold. It can be pressed into sheets and drawn into filaments. 1 gram of silver can be drawn into 1800 meter long filaments and rolled into1100000 mm thick silver foil. Among all metals, silver has the best electrical and thermal conductivity. Silver is also very reflective to light, and the reflectivity can reach 9 1%.
2. Silver is chemically inactive and does not react with oxygen at room temperature. Silver is a relatively stable element. Exposure to air for a long time will combine with hydrogen sulfide in the air and the surface will turn black to form black silver sulfide. At room temperature, halogen can slowly combine with silver to form silver halide. Silver can react with strong oxidizing acids (concentrated nitric acid and concentrated hydrochloric acid). Silver powder is easily soluble in cyanide solution containing oxygen and acidic thiourea solution containing oxygen. Silver has good alkali resistance. Silver exists in univalent form in compounds and can form compounds with many substances.
3. Main uses of silver
1) currency function
Silver has the property of currency and has been used as currency like gold for a long time in history. In the history of international currency, besides the gold standard, there has also been a silver standard. With the reform of monetary system and the emergence of credit currency, silver coins gradually withdrew from circulation. At present, the silver coins cast are mainly investment silver coins and commemorative silver coins; In addition, the consumption of other investment objects such as silver bars is also increasing.
2) Industry and high-tech industries
Silver has the best electrical and thermal conductivity, good flexibility, ductility and reflectivity. The industrial application of silver and its function of decorating and beautifying life are constantly being exerted, which are mainly used in the fields of electronic and electrical industry, photography, solar energy, medicine and jewelry, silverware, silver coin making and so on. The versatility of silver makes its application irreplaceable in most industries, especially in high-tech industries that need high reliability, higher precision and safety. Silver can be used in thick film slurry, and reticulated and crystalline silver can be used as catalysts for chemical reactions. Silver nitrate is used for silver plating and can be used to make silver mirrors. Silver iodide is used for artificial rainfall. Silver ions and silver compounds can kill or inhibit bacteria, viruses, algae and fungi, and the reaction is similar to that of mercury and lead. Silver is also called bionic metal because of its disease-resistant effect.