The silver

مرسلة بواسطة Unknown في 6:16 م

White metal with a high degree of luster and can be refined and polished to a high degree. With the exception of gold, silver is one of the most retractable metals and roads, and in terms of heat and electricity, it outperforms all other metals. Its strength ranges from 2.5 to 2.7 on a moss scale, which is more hardened than gold but better than copper. The silver metal in the transition group (II) of the periodic table, and its atomic number (47), and its atomic weight is 107,868, and its weight is 10.5. Silver is fused at a temperature of 962 ° C. And boil at a temperature of (2212) ° C. Characteristics of silver Silver is free in nature as it is found in the form of ores, the most prominent of which are silver sulphide ores and silver chloride. Silver is also found in ores and arsenic, and copper, zinc and lead materials often contain silver. And that a large part of the silver lag behind the ore mining materials mentioned above. Silver is superior to all metals in its ability to deliver heat and electricity and lagged behind gold only in its ability to drive and pull, in the work of laminate sheets and very fine wires. Silver is melted at a temperature of 960 ° C, if heated in vacuum or in an atmosphere of nitrogen, and fused into the air at a temperature of 923 ° C, so that the oxygen is evaporated from the air. The melting of oxygen in the molten silver increases as the molten temperature rises , At a temperature of (973) centimeter centimeter of the silver fuse (20.3) cubic centimeter of oxygen and silver melt (RFID) in nitric acid, the center of it and the diluted silver nitrate. It is also affected by the sulfuric acid of the hot center to be silver sulfides but it holds up in the face of hydrochloric acid and alkalis. History of silver metal Since ancient times, silver has been known as a valuable decorative metal and used as a coin. Several mines were built in Asia Minor before 2500 BC. and in Islamic era silver was used in making pots and money. In the fourth century AH / 10th century AD, al-Biruni pointed to the presence of silver mixed with gold, not mixed with it, and it seems that it is meant to blend the elements. The mixing is the mixture that we mean nowadays in chemistry. He says in his book Al-Jumhur: "In the village of Sanana near Zaruban In some cases, iron mixed with silver is not blended and was peeled off and is distinguished from non-melting, found in it a piece of pure silver in iron metals cut and cut secretly. Chemically, silver is not a very active metal. Silver does not dissolve in dilute acids and in alkali but melts in concentrated nitric acid or sulfuric acid, and does not react with oxygen or water at normal temperatures. Both sulfur and silver sulphide attack, and silver may lose its luster due to silver sulphide formation on the surface of the metal. Bleach, which contains a reasonable amount of sulfur as a component of the protein - silver loses its luster very quickly. Its luster is also lost by small amounts of naturally occurring sulphides in the atmosphere that are added to domestic gas, such as hydrogen sulphide. Silver sulphide is one of the most insoluble salts in aqueous solutions. This property is used to separate silver ions from other positive ions. Uses of silver Silver metals have little interest in coins, ornaments and ornaments, but silver salts and their compounds are widely used, especially in analytical chemistry and photographic filaments. Silver is also widely used in the jewelry and coin industry. Silver is usually mixed with small amounts of other metals to be stronger and more durable. Pure silver is used in the manufacture of tableware and other solid silver materials, where the proportion of silver in these materials is 92.5% while the proportion of copper 7.5%. Silver is also used to cover the soft glass surfaces used in the manufacture of mirrors. This process is carried out by evaporating the metal or depositing it from dissolved solution. However, aluminum has replaced silver in this area to a large extent. Silver is widely used in the manufacture of circuits for electrical and electronic components. Silver salts, such as silver bromide, silver chloride, and silver oxide, which become black when exposed to light, are used in the manufacture of sensitive layers used in plates, film and paper. These salts dissolve in sodium sulphate, the compound used in the photographic stabilization process. It also uses dilute solutions of silver nitrate and some insoluble compounds such as potassium in pharmaceutical industries such as antiseptics and antimicrobials. Ergirol, a silvery protein compound, is purified topically for the eye, ear, nose and neck.