That physical properties of metals for the most part determine the field of application technology and people in the industry.Among the main characteristics of considerable importance is the temperature of melting.Knowledge of this parameter allows you to successfully combine different ingredients and create comfortable, durable and high-quality alloys, especially suited for use in the home.
melting point and boiling point of metals
for each representative of a given indicator.However, the limit of heating is at all metals.At a certain temperature, they begin to melt, going from a solid to a liquid state.If we bring the figure up to a critical value, the metal goes into a gaseous state, ie, begin the process of boiling and evaporation.
Therefore, there is an entire classification, reflecting the ability of metals to melt.All of them fall into the following groups.
-
Fusible.This group includes those that melt at rates below 600 ° C.Example: zinc, sodium, gallium, bismuth, tin, cesium, and others.
- medium meltability.Indicator within 600-1600 ° C.For example, the melting point of pure gold - 1063 ° C, then it belongs to this group of metals.
- Refractory.More than 1600 ° C.Examples: titanium, tungsten, chromium and others.
should be noted that this classification is valid only for pure metals.When it comes to alloys, the numbers change dramatically, and the values may differ from the baseline.
boiling point of metals is significantly higher than the considered parameter.Thus, if the melting point of gold - 1063 ° C, the boiling point - is 2947 ° C.The difference is almost double!
Gold: general characteristics
Aurum, or gold - is a chemical element at number 79 in the periodic table.The atomic mass of 196.967 units.Located in group I, subgroup side.It refers to the precious metals, in addition to:
- platinum;
- silver;
- palladium.
From the viewpoint of reactivity is virtually inert, no special conditions do not react.It has special physical properties, allowing its use in jewelry, art, industry.
physical properties of gold
What is so unique in the metal, which was for many centuries chasing people and which became a symbol of financial well-being in the world?
- color.For pure gold typical beautiful rich yellow color with a pronounced metallic sheen.Liquid metal has a pale green color.Couples its yellow-green color.
- hardness.Using this parameter gold inferior to many other members because it is a soft metal.On a scale of hardness materials (Mohs scale), this figure is 2.5-3.
- melting point of gold - 1063 ° C.
- Conductivity is good, is 75% relative to the copper as a superconductor.
- thermal conductivity and heat capacity is also excellent.Products from gold instantly heated and are heated quickly.
special properties that give high value of gold, considered separately.It:
- ductility;
- plasticity;
- density.
density metal
very characteristic density means the weight of a substance per unit volume.So gold has almost the highest figure for a given parameter.For example, half a cup of pure golden sand will have a weight of about 1000 grams.
density of gold, purified from impurities is 19.3 g / cm3.If we talk about the natural rocks of gold, then it is somewhat lower figure - 18-18,2 g / cm3.This indicator allows you to conveniently extract the metals from the rocks.He also makes gold so expensive for the very small number of grams.
malleability and ductility
melting point of gold, as well as its extreme malleability and ductility make it user friendly and docile in the hands of experienced people.So, on hearing the term "gold leaf".What it is?It rolled into the thinnest slices of translucent sheets of gold, which it does not lose its bright and beautiful shine.Gold leaf can cover the surface of products, walls, domes, churches and so on.
total of 1 g of this amazing metal can be made very thin wire, the length of which will amount to almost 3000 meters!Gold is easily subjected to the following deformations without loss of properties and the integrity of the structure:
- compression;
- collapse;
- bending;
- grinding;
- rolling;
- stretching;
- giving any desired shape.
Naturally, such a set of physical properties can not remain unnoticed by the people and, therefore, gold is used in various fields of science, technology and industry.
Being in nature and human use
intact gold occurs in nature in the form of ingots, sand or inclusions in the rocks.Placer gold - it is the place of their production man.In a mixture of sand, clay and other parts is removed, and then separated in a pure form.
as gold is contained in:
- plants;
- animals;
- the human body;
- groundwater;
- seas and oceans;
- lithosphere.
Of all these places, people learned to extract metals for use in their needs.Why do I need it?
- biggest industry - is, of course, jewelry.Beautiful decorations made from different alloys of gold are the main feature of the financial wealth of almost every woman.They are given to loved ones, they invest, they are admired and appreciated.
- technique.Melting of gold and platinum, and palladium, nickel, and some other metals makes them very valuable for use in technical applications.A property of gold have a high degree of malleability and ductility, combined with chemical inertness allows to use wire of this metal in the smallest detail, chips.For example, phones, televisions, calculators, and other electronic devices.
- Gold - hard currency around the world, which is not depreciated ever.He was not afraid of inflation and default, so many keep their savings is in ingots of metal.
- Awards for achievements in different sports, tournaments and games are executed in gold, silver and bronze, which once again emphasizes their high value.
gold alloy
These characteristics of the metal in its pure form make it not only unique and popular, but also affect the quality of products.Thus, due to the high softness of pure gold jewelry is easy to deform, bruise and spoil.Therefore the most commonly used metal alloys with other members of the periodic system.
- 585 gold.This alloy is the most sold and distributed in the country and abroad.Of what it consists?58.5% - pure gold, 34% are copper, 7.5% - Silver.The melting point of gold 585 - about 840 ° C, which is significantly lower than that of pure sample.However, the overall properties of the alloy is much better since the impurities compensate disadvantages simple metal.Copper serves to enhance the strength and hardness of the product.However, if it is too much, then the product will undergo rapid corrosion.Silver affects the color.Thanks to him, a fusion of yellow, shiny, without admixture of green.The fact that the melting point of gold 585 is so low compared to the net option, says that contact with the products must be extremely cautious and careful and not leave near open flames.
- Gold 999. This alloy - on the basis of an essentially pure metal with a small proportion of copper.Because of this, the melting point of gold 999 increases as compared with the previous figure.It is 1063 ° C, i.e. the same value as for the simple substance.Products made of this alloy softer, capable of deformation, therefore, require careful handling and special care.
Gold 375
melting point of gold is a 585 average.Indeed, there is an alloy in which the share of the precious metal is necessary only 37.5% (375 samples).In such an embodiment a melt index generally nearing 770 ° C, which is the minimum value.
Speaking of the base alloy of gold and silver, these options are not used.The product will be too soft.Therefore, copper is present necessarily.The melting point of silver and gold is approximately the same, the variation is small.The white metal it is 961.8 ° C.Therefore, they are not too cooperative alloy lowers overall in the product.
What determines the color of gold jewelry?
What color is molded decoration on light, it depends on what kind of additives in the mix and what their percentage.The red color will have a product in which the 50/50 copper-gold and silver.
White - if the mixture introduce palladium, nickel silver and more.Green - silver and copper, pink - silver, palladium and copper.
