1. Gold is a simple form of chemical element gold (Au), which is a soft, golden yellow and corrosion-resistant precious metal. Gold is a rarer, more precious and more valuable metal. Generally speaking, the gold in the world is in ounces. In ancient China, gold was measured in ounces, which was a very important metal. It is not only a special currency for reserve and investment, but also an important material for jewelry industry, electronics industry, modern communication and aerospace industry.
The chemical symbol of gold is Au, and the financial English code is XAU or gold. The name Au comes from a story of Aurora, the goddess of dawn in Roman mythology, which means shining dawn.
As of 202 1, 10, 12, the gold price is 1760 USD/oz.
Second, the physical properties
1, color:
When gold melts, the steam emitted is yellow-green; Its gold powder is usually brown when it is melted; If it is cast into thin slices, it can transmit green light.
2. Extensibility:
Extremely powerful. 1 oz gold can be stretched to 50 miles long, and its ductility makes it easy to cast, making it a good choice for making jewelry. Of all metals, gold has the greatest pulling force.
3. Extensibility:
Bend your finger for the first time. It will cause extremely thin gold sheets to roll up easily. Gold weighing 65,438+0 ounces can be hammered into 4 million pieces as thin as 65,438+0 feet.
Moreover, the area of 100 square meter is very large. The ancients hammered it into thin slices and spread it in temples and palaces for decoration. All these can explain the flexibility and ductility of gold.
Third, the color of gold is golden yellow, which has metallic luster and is not easy to decompose. Density 19.3g/cm 3, melting point1064.4℃; Good ductility, can be pressed into thin foil, and has extremely high heat and thermal conductivity. The resistance of pure gold is 2.4P Pure gold has good chemical resistance and is the best electroplating material.
4. As a precious metal, gold has good physical properties. "Real gold is not afraid of fire" means that gold has high chemical stability and is not easy to react with other substances, so there is no need to worry about oxidation and discoloration. Even in the molten state, it will not be oxidized and discolored, and it will still be golden yellow after cooling. High density and heavy touch. Good toughness and ductility, good electrical conductivity. Pure gold is bright yellow, but the color changes greatly after mixing with other metals, such as gold-copper alloy is dark red, and silver-containing alloy is light yellow or grayish white. Gold is easily ground into powder, which is also the reason why gold is dispersed in nature. Pure gold jewelry is also easy to wear and lose weight.
In Mendeleev's periodic table, the atomic number of gold is 79, that is, the nucleus of gold contains 79 protons, which are positively charged. At the same time, gold has good chemical stability because it conforms to the half-full law. In the metal market, gold and nails, basking, palladium, money, graupel, platinum and other metals are collectively called precious metals.
Although gold is a very soft metal, it is not as good as lead and tin. Nails can be used to draw marks on pure gold, which makes gold very easy to process. But this is not ideal for the manufacturers of decorations, because it is easy to scratch the decorations, make them lose their luster and even affect their appearance. Therefore, when gold is used to make jewelry, copper and silver are usually added to improve its hardness.
Gold is easy to forge and extend, and can be ground into transparent and green gold foil with a thickness of 0.001mm. 0.5g of gold can be drawn into160m long gold wire.