Gold And Its Amazing Features
His beautiful color - rare among metal - and his wonderful glow are most likely the first qualities that have attracted people to gold since prehistory. And using it, they found the weather and other qualities, thanks to which they valued more, for millennia. Until today, gold continues to be highly valued in both art and science because of its remarkable properties. At first, it was perhaps that could be valued for easy processing: from pieces of native gold (found as such) could be reached fairly quickly ornaments: gold can be processed easily, even cold, even with of primitive tools. This property, called malleability, made possible to obtain the most beautiful jewelry, but also the most sumptuous gilded decorations. Gold is verymalleable and ductile of the metals. Due to the extraordinary malleability (ability to withstand high compressive forces, which manifests itself can be stretched into sheets without breaking), gold can be beaten by a fine foil incredible: a single gram is obtain a thin film, translucent, with an area of 1 square meter! Ductility is seen in the possibility of being drawn into wires - the wires that can be obtained are thinner, the metal is more ductile. Delicate gold jewelry wire, sometimes true gold wire lace, can be made because of metal ductility. Gold is one of the most dense metals - or of the hardest, as they say in familiar language, is heavier than lead, which has a density of 11 340 kg/m3, while gold is 19 300 kg/m3. (The heaviest metal, the highest density is osmium - 22 610 kg/m3).
What other interesting features has the gold? For example,is a good conductor of electricity and heat, while strongly reflecting infrared radiation. Due to these properties, finds many uses in industry, in all sorts of fields, from electronics manufacturing to manufacturing of components of space suits. (I'll devote a specific article uses Technology gold - are many and certainly surprising to those who were accustomed to seeing in gold, first, the raw material for the manufacture of coins and jewelry.)gold formed readily alloyswith other metals, a property of that man seized much gold alloys known for millennia. For example, an alloy calledelectrumwas used in Egypt since the third millennium BC, the Bronze Age.Electrum, constituted mostly of gold and silver (in varying proportions), with traces of copper, platinum and other metals, and naturally there (proof of the ease with which gold alloy form) and was subsequently made and artificial, are used to masters of vessels and coins it.
Today, this kind "friendly" to gold, which makes it easy to ally with different metals, is the most used in jewelry. Pure gold, so-called 24-carat gold is soft and therefore little resistance to deformation.Therefore, in practice, for making jewelry using gold alloys actually with various other metals, which allows the mechanical quality improvement and sustainability, and obtain different shades of yellow gold usual.
A high quality gold, which was highly appreciated, is its great resistance to environmental factors, the ability to maintain strength and brightness even in contact with substances that destroy or damage other metals. Air, water and many corrosive compounds have no effect on gold. And this is possible due to its chemical reactivity is very low. Although it is not inert (non-reactive completely), there are very few substances that can corrode or dissolve it. One of these substances, known from the Middle Ages, theroyal water(aqua regia), a mixture of highly corrosive nitric acid and hydrochloric acid. (In the name of "royal water" medieval alchemists thought recognize patterns: royal water was needed to accommodate the HAC "king of metals" - gold).It is interesting that none of the two acids can not dissolve, alone, gold, only the combination of them can do, because, in combination, each acid performs a certain role and it is these "cooperation" is possible dissolution of the metal. (Nitric acid may, however, alone, to dissolve silver and base metals, a property used to distinguish gold from other metals, the so-called acid test.) Another substance that dissolves gold is mercury, resulting in an alloy called amalgam of gold. This property of the state at all ages, based on a method of extracting gold from ore - amalgamation method. And finally, gold can be dissolved in alkaline cyanide solutions - again a phenomenon that underlies a method of extraction, cianurrii method, used widely today in the gold mining industry. And, since the methods of extraction is an important chapter in the story of gold, we will devote the next day, two special items.