Gold, the symbol of the chemical element Au, is a soft, golden yellow and corrosion-resistant precious metal. Gold is valuable, and its value content is relatively high. The international gold price unit is USD/oz, while the China gold price unit is RMB/gram. If you want to participate in future gold investment and get the opportunity of increasing investment value in the gold market, you must understand the attributes, characteristics and functions of gold in monetary finance. Gold is one of the rarest and most precious metals in the metal kingdom. In ancient times, it was mainly used as currency, decoration and jewelry, and it was the most precious metal. At 175 1, platinum was found, which is more scarce, more widely used and more difficult to extract, so it is more precious. So now, gold has changed from the first precious metal to the precious metal alongside platinum, but it is still the most popular precious metal as jewelry material and electronic information material because of its pure texture, bright color and many excellent characteristics.
[Edit this paragraph] 1. Physical and chemical characteristics of gold
Physical and chemical properties of 1. 1
Gold (transition metal)
Crystal structure: face-centered cubic structure
Atomic weight: 196.5504
Shell structure: 2,8, 18,32, 1 8,1.
Electronic configuration: [xe] 4f145d106s1.
Valence: 1, 3
Melting point: 1064.43℃
Boiling point: 2808℃
Electronegativity: 2.54
* * * Price radius:1.34a.
Ion radius: 0.85 (+3) a.
Atomic radius:1.79a.
Atomic volume:10.2cm3/mol
First ionization potential: 9.2257V
Secondary ionization potential: 20.521v.
Oxidation state: (3), 1
Density at 293K:19.32g/cm3.
Specific heat capacity: 0. 128J/gK
Heat of vaporization: 334.4kJ/mol
Heat of fusion: 12.55kJ/mol.
Electrical conductivity: 0.452x10 6/cm ω/cm ω.
Thermal conductivity: 3. 17W/cmK
Elastic coefficient: 78.3 X 10E3 MPa.
Coefficient of thermal expansion:14.2x10 (-6)/k.
Lattice parameter: 4.0786A
1.2 physical properties
Color: The beauty of golden yellow is comparable to that of the sun. The steam released when gold melts is green; Its gold powder is usually brown when it is melted; If it is cast into thin slices, it can transmit green light.
Ductility: unusually strong. 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.
Extensibility: second to none. It will cause extremely thin gold sheets to roll up easily. Gold weighing 1 ounce can be hammered into 1 foot thickness and 100 square foot thickness. The ancients hammered it into thin slices and threw it into temples and palaces for decoration. It is said that 1 ounce of gold can be used to build the roof of a house. If you have a chance to visit these ancient temples, you should pay attention, otherwise free gold coins will fall on your head!
The color of gold is golden yellow, with metallic texture and no cleavage. Hardness 2-3, pure gold 19.3, melting point1070℃; Good ductility, can be pressed into thin foil, and has high heat and thermal conductivity. Pure gold is the best electronic conductor material.
As a precious metal, gold has good physical properties. "Real gold is not afraid of fire" means that gold is not easy to melt under the general flame. 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, there are 79 negatively charged rotating electrons around the nucleus of gold, so gold has good chemical stability. In the metal market, metals such as gold, ruthenium, rhodium, palladium, osmium, iridium and platinum are collectively called precious metals.
Gold is a very soft metal, but it is not as good as lead and tin. It can trace on pure gold with nails, 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.
Gold is easy to wear and become very fine powder, so gold is often widely distributed in nature in a dispersed state.
Gold is a good conductor of heat and electricity, but it is not as good as platinum, mercury, lead and silver.
The melting point of gold is 1063. C, molten gold has high volatility, and its volatility increases with the increase of temperature.
The compressive strength of pure gold is 10 kg/mm2, and the tensile strength is related to the pretreatment method, generally between 10-30kg/ mm2. When the gold wire is cold-drawn, the force is the greatest.
Pure gold has excellent grass yellow metallic luster. It can be said that gold is the yellowest of all metals. There is no pure gold in nature, and metallic impurities (first of all, copper and silver) give gold various colors and tones, from light yellow to bright yellow and red. The color of gold also depends on the thickness of the metal block and its aggregation state. For example, thin gold foil is green under the light, so is molten gold, while unmelted gold is yellow-green, and finely dispersed gold is generally deep red or deep purple.
Natural gold is sometimes covered with a thin film of iron oxide. In this case, the color of gold may be brown, dark brown or even black.
Gold can alloy with many metals, because the atomic radius of these metals is very close to that of gold. The atomic radius of gold is equal to 1.46 angstrom; Bismuth 1.46 angstrom; Silver 1.44 angstrom; Platinum 1.39 angstrom. Therefore, gold can form gold-silver alloy, gold-copper alloy, gold-platinum alloy, gold-palladium alloy and so on. These alloys are not compounds, but solid melts. All metals in the alloy have lower melting points than pure metals. If gold is heated to near the melting point, it can be melted like iron, and fine gold particles can be melted into gold nuggets. (1 angstrom = = 0.00000000 l cm)
Gold powder must be pressurized to fuse together at low temperature.
Melting gold with other metals can not only reduce its melting point, but also change the mechanical properties of gold itself. Containing silver and copper can obviously improve the hardness of gold; Containing arsenic, lead, platinum, silver, bismuth and tellurium can make gold brittle, and lead is more prominent in this respect. If the alloy containing only 1% lead is stamped, it will become fragments. If pure gold contains 0.0 1% lead, its good ductility will be completely lost.
Gold has the ability to absorb x-rays.
Gold is included in the list of compounds, just like the precious metal family, but it can react with some elements after all. Especially with halogen (chlorine, bromine, iodine) compounds to generate AuCl or AuC 13. Gold can also be combined with cyanide, mercury and hoof. In fact, there are only compounds of gold and hoof in nature, and there are few compounds of gold and mercury. All other compounds are manufactured by hand, and "regin" (Au (NH) 3 (CH) 3) can also be manufactured by hand. "Regin" is easy to explode when it is impacted or heated.
Although gold is difficult to dissolve, it can still be dissolved in some solutions. A small amount of gold can also be dissolved in water containing chlorine, sulfuric acid or corrosive acid. In aqua regia and dilute cyanide solution, it is dissolved in a large amount in ionic state.
The crystal of gold belongs to the equiaxed system. Crystals are usually cubic or octahedral in shape. The crystal melts and then condenses, which is an irregular polygon. The slower the cooling, the bigger the crystal.
1.3 chemical properties
Gold has stable chemical properties and strong corrosion resistance. Generally, it is not oxidized from normal temperature to high temperature in air, and it is insoluble in single strong acid gold such as hydrochloric acid, nitric acid and sulfuric acid, but only soluble in mixed acid (aqua regia) of hydrochloric acid and nitric acid to generate chloroauric acid H [AUCL 4]. At room temperature, in the presence of oxygen, gold can be dissolved in a solution containing potassium cyanide or sodium cyanide to form a stable complex M [Au (CN) 2]. Gold can also be dissolved in a solution containing thiourea; It is also dissolved in an acidic solution containing chlorine. Gold does not react with alkali solution, but it can react with sodium peroxide in molten state to generate NaAuO2 _ 2. The valence of gold is-1, -2,+1, +2, +3, +5, +7 and so on. The oxide is gold trioxide and the chloride is gold trichloride. In acidic medium, chloroauric acid H [AUCL _ 4] or complex M [Au (CN) _ 2] can be reduced to elemental gold powder by metal zinc (zinc powder or zinc wire), sodium sulfite and hydrazine hydrate. The sulfide of alkali metal will corrode gold and produce soluble sulfide gold. Humic acid in soil and metabolites of some bacteria can also dissolve trace amounts of gold.
The ionization potential of gold is very high, so it is difficult to lose the outer electrons and turn them into positive ions, and it is also difficult to accept that electrons turn into anions. Its chemical properties are stable and its affinity with other elements is weak. So it exists in the form of simple substance in nature, that is, natural gold.
The average content of gold in the crust is about 65438+1.1(0.001ppm), and the average content of gold in seawater is about 65438+1(0.00001ppm). The grade of gold in gold mines with general industrial value is 2-3g/ton, that of rich ore is 5-50g/ton, and that of ultra-rich ore is 50-500g/ton. There are gold nuggets, ranging from the smallest10g to the largest dozens of kilograms and hundreds of kilograms of rare gold nuggets. Because some of them are shaped like dog heads, they are commonly known as gold nuggets. Indian scientists have discovered two gold nuggets weighing nearly 2.5 tons. The lean ore is 0. 1- 1 g/ton, which has an industrial mining value of more than 0.5 g/ton at the current level of metallurgical technology.
K gold refers to the gold prepared by silver and copper in a certain proportion according to the formula that pure gold is 24k. Generally speaking, the more silver in K gold, the bluer the color; If the proportion of copper is large, the color is purple. In the early days of liberation, China's K gold was calculated according to the standard of15% per K4. After 1982, it has been harmonized with international standards, taking1666% as the standard. When other elements are added to cooked gold, the color of gold will change. People usually refer to the ripe gold containing only silver and no other metals as "pure gold" and the gold containing silver and other metals as "mixed gold".
[Edit this paragraph] 5. golden
The purity of gold and its products is called success or fineness.
More than 200 years BC, the Greek mathematician Archimedes worried about judging whether a crown was made of pure gold. When he was taking a bath in the bathtub, he discovered what later generations called Archimedes' law of specific gravity: an object immersed in a liquid was subjected to upward buoyancy; Buoyancy is equal to the weight of the liquid it displaces. Thereby successfully confirming whether the crown made by the king is made of pure gold. So, how to express the purity of gold?
5. 1 Use "k gold" to indicate the purity of gold.
Theoretically, we call gold with a content of 100% 24K; ; Therefore, the calculation method is 100/24 (the national standard is in brackets): the national standard GB 1 1887-89 stipulates that the gold content per k (abbreviation of English carat and German carat, often written as "k") is 4. 16666%.
9k= 100/24*9=37.5% (375‰)
14k =100/24 *14 = 58.333% (585 ‰), which is set to 58.5% for easy identification.
18k = 100/24 * 18 = 75%(750‰)
22k =100/24 * 22 = 91.66666% (916 ‰) is set to 9 1.6% for easy identification.
In theory, 100% gold can be called 24K gold, but in reality it is impossible to have 100% gold, so China stipulates that gold with a content of more than 99.6% (including 99.6%) can be called 24K gold.
These kinds of K gold contents are general specifications of jewelry, and gold jewelry below 9K cannot be called gold jewelry.
5.2 Use words to express the purity of gold
Some gold ornaments are marked with words, which stipulate that the gold content is not less than 990‰, and the gold content of thousands of gold is more than 999‰.
In China, the imprint and identification card of gold products are stipulated. Generally, it is the manufacturer's code, material name, content stamp, etc. They are all necessary, and products without marks are unqualified. The same is true internationally. But for some very small products, it is also allowed to be unmarked.
[Edit this paragraph ]6. The value and position of gold
6. 1 Wealth attribute of gold
The rarity of gold makes it very precious, while the stability of gold makes it easy to preserve. Therefore, gold has not only become the material wealth of human beings, but also become an important means for human beings to store wealth, so gold has been particularly favored by human beings.
Green, a gold historian, pointed out: "The civilizations of ancient Egypt and Rome were all cultivated by gold." Grabbing more gold was the motive force for the rulers of ancient Egypt and Rome to give up military activities.
From 2000 BC to 1849 BC, the rulers of ancient Egypt launched four predatory wars against Nubia (a small country rich in gold resources in the upper Nile) and occupied all the gold mines in Nubia. From 1525 BC to 1465 BC, the French king of the 18th dynasty in Egypt launched two wars successively, plundering a great deal of gold and silver from Palestine and Syria. A large amount of gold and silver flowed into Egypt, which greatly increased Egypt's wealth, enabled them to build large-scale water conservancy projects, develop agriculture, build luxurious palaces and cemeteries, and left a huge site of the Amun Temple and pyramids for mankind. The gold coffin in Tutankhamun's mausoleum alone weighs 1 10 kg.
In 47 BC, ancient Egypt was occupied by the Roman Empire. When Julius Caesar triumphed in Rome, he displayed 2822 gold crowns plundered from Egypt, each weighing 8 kilograms, accounting for 22.58 tons. It also shows 18 15 tons of silver. The gold and silver transported to the parade weighed 65,000 tarants, about 1.950 tons. The accumulation of gold and silver greatly enhanced the national strength of the Roman Empire and enabled them to build many magnificent buildings. Although most of these buildings are now in ruins, they still have a far-reaching impact on mankind in literature, history, law and philosophy.
Gold is also the material basis of modern industrial civilization.
/kloc-The opening of the new sea route and the discovery of the new continent in the 6th century had a great impact on European economic life. Gold and silver from America and Africa flowed into Europe, which increased the primitive accumulation of European capitalism. Portugal plundered 276 tons of gold from Africa in the16th century; Spain plundered more gold and silver from America. At the end of 16, Spain controlled 83% of the world's gold mining. The influx of gold and silver caused the rise of European prices, and the first price revolution appeared, which greatly promoted the disintegration of European feudalism and the establishment of capitalist relations of production. /kloc-in the 0 th and 7 th centuries, Portugal formed an alliance with Britain in order to fight against Spain and opened its market to British industrial products. At this time, the development of Brazilian gold under the control of Portugal reached a climax, and it was entirely possible for Brazilian gold to be converted into capital, which enabled Portugal to complete the industrial revolution. However, due to the feudal autocracy of the rulers, Portugal became a golden funnel, and most of the gold flowed to Britain. Only 600 tons of gold flowed into the British treasury, and with the inflow from other countries, Britain quickly accumulated huge monetary capital, and took the lead in implementing the gold standard in 17 17, which provided a reliable economic guarantee for the British financial system. Therefore, the second price revolution at this time not only did not affect the British financial industry, but also created conditions for the export of British goods, and the export volume of British products accounted for 1/4 of the world total. The industrial revolution finally happened in Britain.
Although the role of contemporary gold has changed, countries still reserve about 365,438+/kloc-0,000 tons of gold wealth for emergencies. More than 20,000 tons of gold is privately owned investment wealth. Therefore, some people think that of the 6.5438+0.4 million tons of gold produced by human beings for thousands of years, about 40% are financial assets and about 60% are general commodities, whose main function is for consumption.
6.2 Monetary attribute of gold
Gold has a very long history as a currency. The ancient Roman Alexander gold coins unearthed have a history of more than 2,300 years, and the Persian gold coins have a history of more than 2,500 years. The earliest existing gold coin in China is the "love" cast by Chu during the Spring and Autumn Period and the Warring States Period, which has a history of more than 2,300 years. However, these gold coins are only used in a certain range and area. Gold became a recognized international currency in the world during the "gold standard" period of19th century. "gold standard" means that gold can be used as a means of payment for domestic circulation settlement; Can be used as an international hard currency for foreign trade settlement. Although the gold standard was first implemented in Britain as early as 17 17, it was not officially confirmed in the system until 18 16. Later, Germany, Sweden, Norway, the Netherlands, the United States, France, Russia, Japan and other countries announced the implementation of the gold standard. The gold standard system is the peak of the performance of gold currency attributes. Countries around the world have implemented the gold standard for more than 200 years, ranging from several decades, while China has never implemented the gold standard. Later, due to the outbreak of the world war, many countries carried out gold control, and the gold standard was difficult to maintain. On the eve of the end of World War II, under the leadership of the United States, the Bretton Woods Conference was held, and relevant resolutions were adopted to establish an international monetary system centered on the US dollar. But the dollar is linked to gold, and the United States promises to undertake the international obligation of exchanging 35 dollars for an ounce of gold. However, in the 1960s, there were several gold buying waves. In order to safeguard its own interests, the United States first gave up the fixed official price of gold, and then announced that it would no longer undertake the obligation to exchange gold. As a result, the Bretton Woods monetary system collapsed and the non-monetization reform of gold began. This reform began in the early 1970s, and the revised agreement of the International Monetary Fund was approved in 1978. It can be said that the process of non-monetization of gold at the institutional level has been completed.
Marx said: "Money is gold and silver, and gold and silver are not money." Just as gold played the role of functions of money before the gold standard, the non-monetization of gold at the institutional level does not mean that gold completely lost its functions of money:
-gold is no longer used for foreign trade settlement, but when the balance of payments finally balances, gold is still a settlement method acceptable to both parties.
-The non-monetization of gold does not specify the destination of huge gold reserves in various countries. Even the International Monetary Fund (IMF), which holds high the banner of non-monetization of gold, only designated to dispose of16 of the gold reserve, and kept most of it, apparently leaving a tail of monetary gold for itself.
-The euro monetary system, which was born in the late 1990s, made it clear that gold accounts for 15% of the system's currency reserves. This is the return of gold monetization.
-Gold is still the fifth largest international settlement currency after the US dollar, euro, pound and yen. The great economist Keynes revealed the secret of monetary gold. He pointed out: "Gold plays an important role in our system. As the last guard and reserve in an emergency, nothing else can replace it. " Now gold can be regarded as a quasi-currency.
6.3 Commodity Properties of Gold
Making gold ornaments (including jewelry, Buddha decoration, architectural decoration, etc.). ) and gold utensils are the most basic use of gold. If there is any change, it is that gold ornaments are increasingly moving from palaces and temples to the people, from the privilege of dignitaries to mass consumption. Now more than 80% of the global gold supply is absorbed by the jewelry industry every year.
Due to the high price of gold and the relative scarcity of resources, the industrial use of gold is limited, and the proportion of industrial gold in the total world demand is less than 10%. However, some experts believe that jewelry gold will tend to be stable in the future, and the growth of industrial gold will be an important force driving the change of supply and demand structure of gold, so the commercial use of gold needs to be explored in many aspects.
At present, the main uses of gold commodities are jewelry industry, electronics industry, dentists, gold medals and other industrial gold. It should be admitted that the commercial use of gold is still very narrow at present, which is also the result of the strict control of gold as a currency metal by the state for a long time. In the future, with the advancement of the reform of the international financial system; The regression trend of financial gold's commodity attributes is strengthening, and the expansion of gold commodity demand will be more meaningful to the development of gold industry.
platinum
In nature, it often exists in the state of natural minerals and is extremely dispersed. It is obtained by enriching and extracting primary platinum ore.
Element usage:
Platinum is widely used because of its high chemical stability and catalytic activity. It is mostly used to manufacture corrosion-resistant chemical instruments, such as various reaction vessels, evaporating dishes, crucibles, electrodes, platinum nets, etc. Platinum and platinum-rhodium alloys are often used as thermocouples to measure the temperature of 1200~ 1750℃. In chemical industry, it is often used as a catalyst.
Element auxiliary data:
Platinum, like its homologous metals ruthenium, rhodium, palladium, osmium, iridium and gold, exists almost completely as a single substance in nature. Their content in the earth's crust is similar to that of gold, and their chemical inertness is equivalent to that of gold, but the degree of their discovery and utilization is far behind that of gold. Their extreme dispersion in nature and their high melting point may be the reasons for this situation. The largest natural platinum block found so far is 9.6 kg. The melting points of platinum, ruthenium, rhodium, palladium, osmium and iridium are 1772℃, 23 10℃, 966℃, 1552℃, 2054℃ and 24/kloc respectively.
The ancient Indians in South America have already made decorations out of alloys of platinum and gold. Because the content of platinum in platinum series minerals is much higher than other elements, it was first discovered among platinum series elements.
The first mention of platinum in Europe may be in the book published by French mineralogist Scari Ji 1557. He said that all metals can be melted, but there is one kind of metal that can't be melted in Darian Mine and Darinan (now Panama). This can be thought of as platinum.
/kloc-In the mid-8th century, platinum mines in South America were introduced to some European scholars who studied platinum. Many scholars believe that platinum is not a pure metal, but an alloy of gold, iron and mercury, while others think it is a semi-metal. 1752 Swedish chemist Schaefer affirmed that it is an independent metal and called it aurum album (platinum).
W
Tungsten is a rare metal with high melting point, belonging to VIB group in the sixth period (the second long period) of the periodic table of elements. Tungsten is a silvery white metal that looks like steel. Tungsten has high melting point, low vapor pressure and low evaporation rate. Tungsten has very stable chemical properties, does not react with air and water at room temperature, and is insoluble in hydrochloric acid, sulfuric acid, nitric acid and alkali solution. Soluble in the mixed solution of aqua regia, nitric acid and hydrofluoric acid. It can combine with chlorine, bromine, iodine, carbon, nitrogen and sulfur at high temperature, but it cannot be hydrogenated.
They are different kinds of elements.