Dmitry Mendeleev was able to create a unique table of chemical elements, the main advantage of which was periodicity. Metals and non-metals are arranged in the periodic table in such a way that their properties change in a periodic manner.

The periodic table was compiled by Dmitri Mendeleev in the second half of the 19th century. The discovery not only simplified the work of chemists, it was able to combine all the discovered chemical substances in a single system, and also predict future discoveries.

The creation of this structured system is invaluable for science and for humanity as a whole. It was this discovery that gave impetus to the development of all chemistry for many years.

Interesting to know! There is a legend that a scientist dreamed of the finished system.

In an interview with one journalist, the scientist explained that he had been working on it for 25 years and the fact that he dreamed about it was quite natural, but this does not mean that all the answers came in the dream.

The system created by Mendeleev is divided into two parts:

• periods - horizontal columns in one or two lines (rows);
• groups - vertical lines, in one row.

There are 7 periods in total in the system, each subsequent element differs from the previous one by a large number of electrons in the nucleus, i.e. the nuclear charge of each right indicator is greater than the left one by one. Each period begins with a metal and ends with an inert gas - this is precisely the periodicity of the table, because the properties of compounds change within one period and are repeated in the next. At the same time, it should be remembered that periods 1-3 are incomplete or small, they have only 2, 8 and 8 representatives. In the full period (i.e., the remaining four) there are 18 chemical representatives.

The group contains chemical compounds with the same highest value, i.e. they have the same electronic structure. In total, the system contains 18 groups (full version), each of which begins with alkali and ends with an inert gas. All substances presented in the system can be divided into two main groups - metal or non-metal.

To make searching easier, the groups have their own name, and the metallic properties of the substances increase with each lower line, i.e. the lower the compound, the more atomic orbits it will have and the weaker the electronic bonds. The crystal lattice also changes - it becomes pronounced in elements with a large number of atomic orbits.

There are three types of tables used in chemistry:

1. Short – actinides and lanthanides are moved outside the main field, and 4 and all subsequent periods occupy 2 lines.
2. Long - in it the actinides and lanthanides are moved beyond the boundary of the main field.
3. Extra-long – each period takes exactly 1 line.

The main one is considered to be the periodic table that was officially accepted and confirmed, but for convenience, the short version is often used. Metals and non-metals in the periodic table are arranged according to strict rules that make working with it easier.

Metals in the periodic table

In the Mendeleev system, alloys have a predominant number and the list of them is very large - they start with Boron (B) and end with polonium (Po) (the exceptions are germanium (Ge) and antimony (Sb)). This group has characteristic features, they are divided into groups, but their properties are heterogeneous. Their characteristic features:

• plastic;
• electrical conductivity;
• shine;
• easy release of electrons;
• ductility;
• thermal conductivity;
• hardness (except mercury).

Due to the different chemical and physical essence, the properties may differ significantly between two representatives of this group; not all of them are similar to typical natural alloys, for example, mercury is a liquid substance, but it belongs to this group.

In its normal state, it is liquid and without a crystal lattice, which plays a key role in alloys. Only chemical characteristics make mercury similar to this group of elements, despite the conventionality of the properties of these organic compounds. The same applies to cesium, the softest alloy, but it cannot exist in nature in its pure form.

Some elements of this type can exist only for a fraction of a second, and some do not occur in nature at all - they were created in artificial laboratory conditions. Each of the groups of metals in the system has its own name and characteristics that distinguish them from other groups.

However, their differences are quite significant. In the periodic table, all metals are arranged according to the number of electrons in the nucleus, i.e. by increasing atomic mass. Moreover, they are characterized by periodic changes in their characteristic properties. Because of this, they are not placed neatly in the table and may not be placed correctly.

In the first group of alkalis there are no substances that would be found in pure form in nature - they can only exist as part of various compounds.

How to distinguish a metal from a non-metal?

How to determine the metal in a compound? There is a simple way to determine it, but for this you need to have a ruler and a periodic table. To determine you need:

1. Draw a conditional line along the junctions of the elements from Bor to Polonium (possibly to Astat).
2. All materials that will be on the left of the line and in the side subgroups are metal.
3. The substances on the right are of a different type.

However, the method has a flaw - it does not include Germanium and Antimony in the group and only works in a long table. The method can be used as a cheat sheet, but in order to accurately determine the substance, you should remember the list of all non-metals. How many are there in total? Few - only 22 substances.

In any case, to determine the nature of a substance it is necessary to consider it separately. It will be easy to find elements if you know their properties. It is important to remember that all metals:

1. At room temperature they are solid, with the exception of mercury. At the same time, they shine and conduct electricity well.
2. They have fewer atoms at the outer level of the nucleus.
3. They consist of a crystal lattice (except mercury), and all other elements have a molecular or ionic structure.
4. In the periodic table, all nonmetals are red, metals are black and green.
5. If you move from left to right in a period, the charge of the nucleus of the substance will increase.
6. Some substances have weakly expressed properties, but they still have characteristic features. Such elements are classified as semimetals, such as Polonium or Antimony, and are usually located at the boundary of the two groups.

Attention! In the lower left part of the block in the system there are always typical metals, and in the upper right - typical gases and liquids.

It is important to remember that when moving in the table from top to bottom, the non-metallic properties of substances become stronger, since elements that have distant outer shells are located there. Their nucleus is separated from the electrons and therefore they attract weaker.

Useful video

Let's sum it up

It will be easy to distinguish elements if you know the basic principles of the formation of the periodic table and the properties of metals. It will also be useful to remember the list of the remaining 22 elements. But we must not forget that any element in a compound should be considered separately, without taking into account its connections with other substances.

In contact with

How to distinguish one non-ferrous metal from another?

Non-ferrous metal is copper, brass, lead, titanium, aluminum. The price for them is good, but only if the metal does not have impurities and, most importantly, background radiation. In the latter case, the price will drop significantly. If you do not bring the metal to the collection point, but the collection point itself comes to you, you will receive less money, keep in mind. Due to transport costs at the reception point.

How to distinguish ferrous metal from non-ferrous metal? If it is magnetic, then it is ferrous metal or one of the components of such metal - ferrous metal. Everything else is not magnetic.

Stainless steel is also not magnetic, water does not leave marks on it, and it costs much more than ferrous metal. Color – grey.

Copper is a yellow, even golden metal; when it comes into contact with oxygen, it becomes covered with a dark oxide film, and when it comes into contact with water, it becomes covered with green rust. Copper is more expensive than all non-ferrous metals, only precious metals such as silver and gold are more expensive.

Aluminum is a silvery metal, flexible and lightweight, easy to cut and bend, and low in price.

Brass is a heavy metal of yellow color with a slight redness, very similar to gold.

Bronze is dark brown in color, the surface is grainy. Costs about the same as brass. Typically, non-ferrous metals are received in the same place as ferrous metals are received. Precious metals are accepted by special organizations that have special permission from the authorities.

The most popular non-ferrous metal at collection points, for which no expense is spared, is copper. True copper is defined as follows:

If the metal is in good condition, then it will certainly have a golden-pink hue, and in air it will quickly disappear under a brown-green-blue oxide film.

Scrap metal such as water pipes, air conditioner pipes, heat sink pipes (coolers) is almost certainly copper, especially in the case of coolers, since it is not practical to remove heat with more expensive silver and gold, and copper has few competitors here.

Why give it up? Why keep unnecessary things at home, in the garage or outbuildings? If an item is lying idle, then why not scrap it and make money on it? Moreover, the very high price of non-ferrous metals simply encourages this.

This allows the state to save money. Copper is needed for many needs, and if it is possible to extract it through processing without spending enormous amounts of energy on mining ore, transporting it and obtaining the metal, then this is very good for the economy.

How often have you encountered this problem: you need welding, but you don’t know what metal is in front of you and, accordingly, it’s difficult to decide on the brand of electrode or filler rod? Perhaps the need to distinguish metal arose for you for another reason.

How can you find out what kind of metal is in front of you, what its grade is without resorting to special studies, such as spectral analysis, or carbon analysis, etc.?

It is not difficult even for a person not initiated into the intricacies of metallurgical science to distinguish non-ferrous metal from black metal. The easiest way you can resort to is a visual inspection.

Black metal when cutting or cleaning it has a silvery-light color, however, it oxidizes very quickly in air. The oxide has a dull gray shade. The metal is easily picked up by a magnet and is highly corroded, that is, covered with a layer of red rust.

Aluminum and alloys based on it - when freshly cut, the metal is light and shiny and cannot be picked up by a magnet; as it oxidizes it becomes dull. Pure aluminum is whitish in color; the oxidized surface is visually perceived as a white coating.

Copper has a red tint, darkens strongly in air with the formation of a green coating. Can't be picked up with a magnet. When burned, the flame turns green.

Bronze - it is an alloy with copper - it has a yellow tint, oxidizes slightly and is not magnetic.

Brass is an alloy of copper and zinc, almost the same as bronze, only it oxidizes more strongly.

Corrosion-resistant steel (stainless steel) without color, sometimes with a grayish tint, hard-worked stainless steel can be taken with a magnet, annealed stainless steel is not magnetic.

Magnesium - metal with a white silver tint, non-magnetic. It burns with a bright white flame and produces a sweetish taste when inhaled.

Various chemical elements, carved with an abrasive or other wheel, burn in air, each in its own unique way. When cutting or sharpening, you can determine the metal more accurately by the color and shape of the spark and the number of “stars”.

It is known that low-carbon steels, depending on the type of deoxidizing agent added to the melt, are divided into: boiling, calm, semi-quiet.

Boiling steel leaves a few long sparks, colored orange. When keeping large quantities carbon (high-carbon) a beam of numerous light sparks flies out from under the circle, with “stars” at the end. As the percentage of carbon increases, the brightness increases and there are more “stars”.

Tool steel (high-speed cutter) gives a bunch of broken short sparks.

With experience, you can learn to determine the amount of carbon with an accuracy of a tenth of a percent. However, it is almost impossible to distinguish high-quality steel from ordinary steel, since the percentage of harmful impurities such as sulfur and phosphorus, in both cases, is very small and they do not in any way affect the shape, color, size of the spark, etc. . In addition, please note that Art. 20 and St.3, St.4 contain the same amount of carbon and, accordingly, visually you will not see any difference in the nature of combustion.

You can unmistakably determine the presence of tungsten in steel if its more than 3-4% spark turns dark burgundy and this is the main sign that the steel is not carbon.

Cast iron(an alloy of iron with carbon from 2.14%) turns the spark red, you can’t go wrong here.

On impact titanium A bright whitish spark strikes the steel.

Stainless steel gives a similar picture, however, the brightness of the spark is less and it is more difficult to obtain.

Additional research can confirm the brand of material. If you take a steel blank and cut it to 25% of its thickness, and then hit it with a sledgehammer, you will get a fracture, and by studying the nature of it, you can also draw conclusions.

Quick cutter, or rapid(P18, P9 and others) due to its high hardness, it breaks brittlely and the fracture is fine-grained with a dark color. Carbon steel, on the contrary, has a light-colored fracture with a coarse grain. By comparing the data on the type of surface on which the destruction occurred with the results on sparks, we can speak with a high degree of confidence about the correctness of determining the grade of material.

If, despite all the tests carried out, you are still overcome by doubts, then if you have a hardening furnace, you can conduct the following experiment, based on the different ability of steels to harden.

So, steel with a carbon content of up to 0.25% (St. 3-St. 20), after heating to T = 900 degrees, some exposure and subsequent sharp cooling in water, remains as soft and plastic as it was before heat treatment and can be sawed off well a file (it would be nice to have a set of calibrated files with different hardnesses on the farm). Carbon steel with a content of up to 1.3% C can be easily distinguished from low-alloy steel after oil quenching. After such a procedure, the former can be easily sawed with a file, and the latter (alloyed) acquire such a high hardness that the file slides over them (in particular, we are referring to the well-welded grades 9ХС, ХВГ).
It is very difficult to distinguish St.40 and St.50 from St.40X and St.50X from each other by spark, but after hardening, St.40X acquires greater hardness and the file glides over such steel and does not file it down, while St.40 remains soft and pliable. A file, as a means of determining hardness, is used in the absence of other measuring instruments (a Rockwell hardness tester, or a Super-Rockwell hardness tester with a diamond indenter, or an ultrasonic hardness tester based on the phenomenon of ultrasonic contact impedance).
It should be noted that most steels after hardening have a decarburized layer (this layer, accordingly, has low hardness) and it must be removed to obtain correct data.
If the question is to distinguish steel by type of manufacture, the surface of hot-rolled steel is always covered with a coating of scale, while cold-rolled steel has a clean, shiny, uncontaminated surface.

So, to determine the brand of material, you can resort to one of the proposed options:

• visual inspection,
• striking a spark,
• fracture study,
• hardening and checking with a file.

If you examine a sample of material using all these methods and compare the results, then you can talk about one hundred percent accuracy in determining the grade of material. Also, all these options can be used as additional studies when conducting spectral analysis.

additional information

St.12Х18Н9 (AISI 304) gives a short spark, colored light yellow with a few red dots appearing from time to time. At the point of contact with the abrasive and at the ends of the branching, the spark beam has a red-yellow color.

St.X12F1 - yellow, short spark, multiple “stars”, the ends are elongated in a line. The area where the abrasive touches is red-yellow. Individual red dots throughout the entire beam.

St. 12X13 - light yellow short spark with branches.

Today, many owners of private houses are trying to make the most of their own capabilities. We are talking about organizing a workshop. The presence of even a primitive lathe will allow you to produce a wide variety of parts for a wide variety of purposes. In any case, repairing garden equipment or even your own car will become much easier.

Meanwhile, savings can be achieved by purchasing metal raw materials on the most favorable terms. Today on the Internet you can find the most attractive prices for aluminum rods. Many people purchase metal for further use at scrap metal sites. Here the question arises - how to distinguish ferrous metal from non-ferrous metal?

Surveys show that the average person cannot answer this question. The essence of the answer lies in the composition of the metals.

Ferrous metals contain an admixture of iron. Therefore, ferrous metal can be determined using an ordinary magnet. If it sticks to a metal part or workpiece, we can say with confidence that it is made of ferrous metal.

However, there are exceptions to any rule. Nickel also attracts a magnet, although it is considered exclusively non-ferrous metals. Additionally, the magnet rule does not apply to some metal alloys.

These include stainless steel.

These can safely be attributed to:

• aluminum;
• copper;
• brass;
• bronze

However, there is an easier way to identify ferrous metal. If you purchase metal at a dealer (reception point), it is very likely that it is located in the open air.

We are talking about the fact that the metal is affected by precipitation. This means that it is in no way protected from corrosion. Consequently, ferrous metals immediately begin to become covered with rust.

Non-ferrous metals are a priori not subject to corrosion (under the influence of the environment). They are protected by an invisible oxide film that appears on the surface.

The video explains how to recognize metal (non-ferrous or ferrous):

Probably everyone had to hold in their hands a piece of jewelry or another object, obviously metal. But how can you determine what metal is used in production? It could be a precious material or a counterfeit, or even a trinket with no claims to value. Expertise from specialists will give you the exact answer, but it is not free. But there are methods for approximately determining the type of metal at home. They were used a long time ago, but they have not lost their relevance in our time.

Bring the magnet to the item being tested - good way primary check. By the reaction of the magnet you can determine which group the metal belongs to:

1. Ferromagnets. The magnet is clearly attracted to the object, which means that the product may contain iron, steel or nickel.
2. Paramagnetic materials. The interaction with the magnet is very weak. This group includes aluminum and chrome. Among the precious metals that are paramagnetic are platinum and silver.
3. Diamagnets. In general, they do not react to magnets. Copper and zinc have these properties. Precious metals - gold.

Of course, such a check will not allow us to accurately determine the material from which the item is made. After all, a non-magnetic metal may not be in its pure form, but in the form of an alloy with a ferromagnet. But it can confirm or refute the assumption. For example, if you check whether it is gold or not, but the item is clearly magnetic, then you can claim that it is a fake.

When checking jewelry It should be taken into account that, in addition to precious metals, they may contain locks, built-in springs, made of another material. You need to check the metal itself.

Heat check

You can also determine the group of a metal by how it conducts heat. It is known that the thermal conductivity of silver is very high. It is almost five times higher than that of iron or platinum. Slightly worse - for gold, copper and aluminum. Platinum transmits heat even weaker than iron.

If you immerse the metal in hot water for 15–20 seconds, then based on its temperature, determined by touch, you can draw some conclusions.

1. Gold and silver objects will become as hot as the water in which they were dipped.
2. During this time, platinum and items containing iron will become warm, but not hot.

In this way it is easy to distinguish platinum from silver. But it won’t be possible to compare silver or aluminum alloy.

Iodine test

You can check the authenticity of the metal using an iodine solution purchased at a pharmacy. A drop of iodine is applied to the surface and left for several seconds. Iodine will not harm noble metals - gold, platinum, silver. If the color of a drop of iodine does not change, and after removing it with a napkin, no traces or stains remain, this indicates the authenticity of the metal. If darkening is visible at the place of the drop, then this is a low-quality alloy or an outright fake.

Vinegar test

Household vinegar solution also does not affect precious metals. But it is dangerous for counterfeits. But, unlike the iodine test, acetic acid takes time. To wait for the result, you need to immerse the metal being tested in a container with vinegar for 15–30 minutes. The absence of traces of interaction between metal and vinegar is a sign of nobility.

If, in addition to metal, the product contains precious or semiprecious stones, then it’s better not to check them like that, vinegar can ruin them. This is especially true for pearls.

Dental check

From novels and films we know that they used to test the authenticity of gold coins by biting them. What exactly can be installed in this “old-fashioned” way? Gold is a soft metal. Therefore, even with a weak bite, a dent from the teeth remains on it. Fake alloys do not have this property; you cannot take them with your teeth.

Such a check gives good results for high quality products. The higher the pure gold content, the softer it is. Gold of 900 purity and higher is so soft that they try not to expose valuable products made from it to contact with other objects.

Expert opinion

Sidorenko Alexander

Antiques appraiser, numismatist

This is how you can compare platinum and silver. The latter does not have the softness of gold, but a strong bite may leave a small dent. It is impossible to leave marks with teeth on real platinum.

Application of chemicals

Testing with active chemical reagents should be left as a last resort. If handled improperly, they will damage even genuine precious metal. And they can be dangerous for the health of the inspector.

Ammonia

Pure gold does not react to ammonia. But practically no products intended for use are made from gold 900 and 999, only for collections. And on precious metals of lesser purity, ammonia can leave an irremovable mark. Its solution in combination with other substances is used to clean gold items. Therefore, it is not worth identifying gold and silver items using ammonia.

Platinum products are usually produced with a high purity. Therefore, you can check the authenticity of platinum with ammonia. This chemical will not leave a mark on her.

Nitric and hydrochloric acids

Separately, these acids do not affect high-grade gold and platinum. And if you mix their concentrated solutions in a ratio of 1:3, you get a mixture called aqua regia. It can even dissolve gold. Aqua regia does not “take on” platinum when it is cold. This precious metal will gradually dissolve in the heated mixture.

Oddly enough, royal vodka is not afraid of genuine silver. It reacts to it by forming silver chloride in the form of a thin film on the surface. The latter protects the product itself from destruction.

Density check

One of the reliable ways to determine the type of metal or alloy is to determine its density. For pure gold it is two times higher than for copper and almost three times higher than for iron. Platinum is even heavier than gold. Even an alloy of 585 gold is noticeably heavier than base metals.

Of course, to determine the exact density of a small product, you will need pharmaceutical scales, volume calculations (Archimedes' law to help) and tabular data on the density of base metals. But to solve the question of what the alloy is mainly made of, gold or another metal, rough estimates are sufficient. If you have at hand an object made of obviously genuine metal of approximately equal volume, then you may not even need a scale. A weight difference of two to three times is not so difficult to catch.

Separately, each of the considered methods will not give an exact answer to the question of what metal the product is made of. But if several different tests show the same results, you can be confident in the correct determination. If not, then you will have to turn to professionals.