The atomic number of silver is 47, and it is a silver-white precious metal. Silver exists in a small amount in free state in nature, mainly in silver-containing compound ores. Silver has stable chemical properties, low activity, high price, good thermal conductivity and electrical conductivity, not easy to be corroded by chemicals, soft and ductile. Silver has good electrical and thermal conductivity and has the best reflectivity for white light. Silver does not oxidize in dry warm air or oxygen, but in humid air containing sulfur, the surface will turn black, and it is very resistant to alkaline substances. (H2SO4) dissolved. Silver in nature is often mixed with sulfides, or mixed with sulfides of other metals (lead, zinc, copper).