We were taught at school to divide the periodic table diagonally with a ruler, starting with Bor and ending with Astatine, these were the territories of metals and non-metals. Everything above silicon and boron are non-metals.
Personally, I use such a table of periodic elements.
If in the old (abbreviated) version periodic table draw a straight line from the left top corner to the bottom right, then most non-metals will be at the top. Although not all. And there are also semimetals, for example, arsenic and selenium. It is easier to say which elements are non-metals, because there are significantly fewer of them than metals. And all of them are usually highlighted in yellow as p-elements (although some metals get there). In the modern (long) version of the table, with 18 groups, all non-metals (except hydrogen) are on the right. These are all gases, halogens, as well as boron, carbon, silicon, phosphorus and sulfur. Not so much.
I remember how at school the teacher divided the periodic table with a ruler and showed us the territories of metals and non-metals. The periodic table is divided into two zones diagonally. Everything above silicon and boron are non-metals. Also in the new tables, these two groups are marked with different colors.
The periodic table of Mendeleev is more informative than it might seem at first glance. In it, you can find out about the element, whether it is a metal or a non-metal. To do this, you need to be able to visually divide the table into two parts:
What is under the red line are metals, the rest of the elements are non-metals.
How to recognize metal or not metal, metal is always in a solid state, except for mercury, and non-metal can be in any form, soft, solid, liquid, and so on. You can also determine by color, as it has already become clear metal, metallic color. How to determine it in the periodic table, for this you need to draw a diagonal line from boron to astatine, and all those elements that are above the line do not belong to the metal, but those below the line to the metal.
Metals in the table of D.I. Mendeleev are in all periods except the 1st (H and He), in all groups, in the side (B) subgroups there are only metals (d-elements). Non-metals are p-elements and are located only in the main (A) subgroups. There are 22 non-metal elements in total and they are arranged in steps, starting from the IIIA group, adding one element in each group: IIIA group - B - boron, 1UA group - C - carbon and Si - silicon; VA group - nitrogen (N), phosphorus - P, arsenic - As; V1A group (chalcogens) - oxygen (O), sulfur (S), selenium (Se), tellurium (Te), V11A group (halogens) - fluorine (F), chlorine (Cl), bromine (Br), iodine (I ), astatine (At); V111A group of inert or noble gases - helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Ra). Hydrogen is located in the first (A) and seventh (A) groups. If we mentally draw a diagonal from beryllium to bohrium, then non-metals are located above the diagonal in the main subgroups.
Especially for you and so that you can clearly understand how you can easily distinguish between metals and non-metals in the table, I give you the following diagram:
The red marker highlights the separating feature of metals from non-metals. Draw it on your plate and you will always know.
Over time, you simply remember all non-metals, especially since these elements are well known to everyone, and their number is small - only 22. But until you acquire such dexterity, remembering the method of separating metals from non-metals is very simple. The last two columns of the table are entirely devoted to non-metals - this is the extreme column of inert gases and the column of halogens, which begins with hydrogen. In the first two columns on the left, there are no non-metals at all - there are solid metals. Starting from the third group, non-metals appear in the columns - first one boron, then in the 4th group there are already two - carbon and silicon, in the 5th group - three - nitrogen, phosphorus and arsenic, in the 6th group of non-metals there are already 4 - oxygen, sulfur, selenium and tellurium, well, then follows the group of halogens, which was mentioned above. To facilitate the memorization of non-metals, such a convenient table is used where all non-metals are kerchiefed:
Without memorization and the periodic table itself, remembering where the metal and where the non-metal is is unrealistic. But you can remember two simple rules. First rule - metallic properties decreases in a period from left to right. That is, those substances that stand at the beginning are metals, at the very end - non-metals. Just the first are alkali and alkaline earth metals, and then everything else, ending with inert gases. The second rule is that metallic properties increase from top to bottom in the group. For example, take the third group. We will not call boron metals, but under it is aluminum, which has pronounced metallic properties.
The periodic table is one of the main postulates of chemistry. With its help, you can find all the necessary elements, both alkaline and ordinary metals or non-metals. In this article, we will look at how to find the elements you need in such a table.
In the middle of the 19th century, 63 chemical elements were discovered. Initially it was supposed to place the elements according to the increase atomic mass and divide them into groups. However, it was not possible to structure them, and the proposal of the chemist Nuland was not taken seriously due to attempts to link chemistry and music.
In 1869 Dmitry Ivanovich Mendeleev published his periodic table for the first time on the pages of the Russian journal chemical society. He soon announced his discovery to chemists around the world. Mendeleev subsequently continued to refine and improve his table, until she acquired modern look. It was Mendeleev who managed to arrange the chemical elements in such a way that they changed not monotonously, but periodically. Finally, the theory came together in periodic law in 1871. Let's move on to the consideration of non-metals and metals in the periodic table.
How are metals and non-metals found?
Determination of metals by theoretical method
- All metals, with the exception of mercury, are in a solid state of aggregation. They are plastic and bend easily. Also, these elements are distinguished by good heat and electrical conductive properties.
- If you need to define a list of metals, then draw a diagonal line from boron to astatine, below which the metal components will be located. They also include all elements of side chemical groups.
- In the first group, the first subgroup contains alkaline, for example, lithium or cesium. When dissolved, it forms alkalis, namely hydroxides. They have an electronic configuration of the ns1 type with one valence electron, which, upon recoil, leads to the manifestation of restorative properties.
In the second group main subgroup are alkaline earth metals like radium or calcium. At ordinary temperature they are solid state of aggregation. Them electronic configuration has the form ns2. transition metals located in side subgroups. They possess varying degrees oxidation. AT lower degrees main properties appear, intermediate degrees reveal acid properties, and amphoteric in higher degrees.
Theoretical definition of non-metals
First of all, such elements are usually found in liquid or gaseous state, sometimes in solid . When trying to bend them they break due to brittleness. Non-metals are poor conductors of heat and electricity. The non-metals are at the top of the diagonal line drawn from boron to astatine. Non-metal atoms contain a large number of electrons, which is why it is more profitable for them to accept additional electrons than to give them away. Non-metals also include hydrogen and helium. All non-metals are located in groups from the second to the sixth.
Chemical methods of determination
There are several ways:
- Often have to apply chemical methods definitions of metals. For example, you need to determine the amount of copper in an alloy. To do this, apply a drop nitric acid to the surface and after a while time will go steam. Blot the filter paper and hold it over a flask of ammonia. If the spot turns dark blue, then this indicates the presence of copper in the alloy.
- Suppose you need to find gold, but you don't want to confuse it with brass. Apply to surface concentrated solution nitric acid in a ratio of 1 to 1. Confirmation a large number gold in the alloy there will be no reaction to the solution.
- Iron is considered a very popular metal. To determine it, you need to heat a piece of metal in hydrochloric acid. If it is really iron, then the flask will turn into yellow. If chemistry is enough for you problematic topic then take a magnet. If it is really iron, then it will be attracted to a magnet. Nickel is determined by almost the same method as copper, only additionally drop dimethylglyoxin on alcohol. Nickel will confirm itself with a red signal.
Other methods are determined in a similar way. metal elements. Just use the necessary solutions and everything will work out.
Conclusion
Periodic table of Mendeleev - an important postulate of chemistry. It allows you to find all the necessary elements, especially metals and non-metals. If you learn some features chemical elements, you can identify a number of features that help you find the desired element. You can also use by chemical means definitions of metals and non-metals, as they allow in practice to study this complex science. Good luck with your study of chemistry and Mendeleev's periodic table, it will help you with further scientific research!
Video
From the video you will learn how to determine metals and non-metals according to the periodic table.
3 parts: Structure of the table Symbols of the elements Calculating the number of neutrons from atomic mass If the periodic table seems difficult for you to understand, you are not alone! Although it can be difficult to understand its principles, learning to work with it will help in the study of natural sciences. To get started, study the structure of the table and what information can be learned from it about each chemical element. Then you can start exploring the properties of each element. And finally, using the periodic table, you can determine the number of neutrons in an atom of a particular chemical element.
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seasons; Times of Day; days of the week ... In the middle of the 19th century, D.I. Mendeleev noticed that the chemical properties of elements also have certain sequence(they say that this idea came to him in a dream). The result of the miraculous dreams of the scientist was the Periodic Table of Chemical Elements, in which D.I. Mendeleev arranged the chemical elements in order of increasing atomic mass. AT modern table chemical elements are arranged in ascending order of the element's atomic number (the number of protons in the nucleus of an atom).
Complete list of metals known to science
What are metals? Elements that lose electrons easily, that are shiny (reflective), malleable (can be molded into other shapes), and are considered good conductors of heat and electricity are called metals. They are crucial to our way of life, as they are not only part of structures and technologies, but also essential to the production of almost all items. Metal is even in human body. When you look at a multivitamin's ingredient label, you'll see dozens of compounds listed.
Definition of metals and non-metals in the periodic table.
How to determine metal or non-metalIn the section Natural Sciences to the question of how to determine from the periodic table where is a metal and where is a non-metal? the best answer given by the Proscenium author is non-metals: H———————He ——B, C, N, O, F, Ne ———Si, P, S, Cl, Ar ————As, Se Br, Kr —————Te, I, Xe ——————-At, Rn The rest are metals
Nonmetals | Position in the periodic table
They are characterized by the properties of both metals and non-metals. Depending on the density, metals are divided into light (density 0.53 × 5 g/cm?) and heavy (5 × 22.5 g/cm?). Between metals and non-metals are semi-metals (metalloids). For example, in the IA(1) group, all elements from lithium (Li) to francium (Fr) donate one electron. In their "pure" form, these elements are, of course, metals and have all the properties of metals.
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Metals and non-metals in the periodic table — Article holding
Chemistry is one of the most ordered sciences. Although this has been known for a long time, the final proof was formulated by Mendeleev and expressed in the form of a periodic table. It was based on the atomic mass of the elements, modern scientists do this based on the number of protons and neutrons in the nucleus. One way or another, both options come down to the same scheme.
How to use the periodic table
Non-metals - elements from the 14th to the 16th groups of the periodic table. They almost do not conduct electricity and heat. Non-metals are very brittle and practically do not bend and any other deformations. They can exist in 2 out of 3 states of matter at room temperature: gas (e.g. oxygen) and solids(e.g. carbon). Non-metals, do not have a metallic luster and do not reflect light.
Metals and various non-metals in the periodic table of Mendeleev: signs and properties
Nature has a certain cyclicity and repetition in its manifestations. Ancient Greek scientists also paid attention to this when they tried to decompose the nature of things into components: elements, geometric figures and even atoms. Scientists of our time also pay attention to the signs of repetition. For example, Carl Linnaeus, based on phenotypic similarity, was able to build a system of living beings.
How to recognize metal or non-metal in the periodic table?
I know about “drawing a line from boron to astatine”. But here I have a problem: Fe, for example, is above the line, but it is a metal. Are there any exceptions or what? The second question are those elements that are on the line, they also have the properties of both metals and non-metals. Do they form a metallic bond?
The properties of chemical elements allow them to be combined into appropriate groups. On this principle, a periodic system was created, which changed the idea of existing substances and made it possible to assume the existence of new, previously unknown elements.
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Periodic system of Mendeleev
The Periodic Table of Chemical Elements was compiled by D. I. Mendeleev in the second half of the 19th century. What is it, and why is it needed? It combines all the chemical elements in order of increasing atomic weight, and all of them are arranged so that their properties change in a periodic manner.
Mendeleev's periodic system brought into a single system all the existing elements that were previously considered simply separate substances.
On the basis of its study, new chemical substances. The significance of this discovery for science cannot be overestimated., it was far ahead of its time and gave impetus to the development of chemistry for many decades.
There are three most common table options, which are conventionally referred to as "short", "long" and "extra long". ». The main table is considered to be a long table, it approved officially. The difference between them is the layout of the elements and the length of the periods.
What is a period
The system contains 7 periods. They are represented graphically as horizontal lines. In this case, the period can have one or two lines, called rows. Each subsequent element differs from the previous one by increasing the nuclear charge (the number of electrons) by one.
Put simply, a period is a horizontal row in the periodic table. Each of them begins with a metal and ends with an inert gas. Actually, this creates periodicity - the properties of elements change within one period, repeating again in the next. The first, second and third periods are incomplete, they are called small and contain 2, 8 and 8 elements, respectively. The rest are complete, they have 18 elements each.
What is a group
Group is a vertical column, containing elements with the same electronic structure or, more simply, with the same higher . The officially approved long table contains 18 groups that start with alkali metals and end with inert gases.
Each group has its own name, which makes it easier to find or classify elements. The metallic properties are enhanced regardless of the element in the direction from top to bottom. This is due to an increase in the number atomic orbits- the more of them, the weaker electronic communications, which makes the crystal lattice more pronounced.
Metals in the periodic table
Metals in the table Mendeleev have a predominant number, their list is quite extensive. They are characterized common features, according to their properties, they are heterogeneous and are divided into groups. Some of them have little in common with metals in physical sense, while others can exist only for fractions of a second and are absolutely not found in nature (according to at least, on the planet), because they were created, more precisely, calculated and confirmed in the laboratory, artificially. Each group has own signs
, the name is quite noticeably different from the others. This difference is especially pronounced in the first group.
The position of the metals
What is the position of metals in periodic system? Elements are arranged by increasing atomic mass, or the number of electrons and protons. Their properties change periodically, so there is no neat one-to-one placement in the table. How to determine metals, and is it possible to do this according to the periodic table? In order to simplify the question, a special technique was invented: conditionally, at the places where the elements are connected, diagonal line from Bor to Polonius (or to Astatus). Those on the left are metals, those on the right are non-metals. It would be very simple and great, but there are exceptions - Germanium and Antimony.
Such a “method” is a kind of cheat sheet, it was invented only to simplify the memorization process. For a more accurate representation, remember that the list of non-metals is only 22 elements, therefore, answering the question of how many metals are contained in the periodic table
In the figure, you can clearly see which elements are non-metals and how they are arranged in the table by groups and periods.
General physical properties
There are common physical properties metals. These include:
- Plastic.
- characteristic brilliance.
- Electrical conductivity.
- High thermal conductivity.
- Everything except mercury is in a solid state.
It should be understood that the properties of metals vary greatly with respect to their chemical or physical essence. Some of them bear little resemblance to metals in the ordinary sense of the term. For example, mercury occupies a special position. She is at normal conditions is in liquid state, does not have crystal lattice, to the presence of which other metals owe their properties. The properties of the latter in this case are conditional, mercury is related to them in more chemical characteristics.
Interesting! Elements of the first group, alkali metals, in pure form do not occur, being part of various compounds.
The softest metal that exists in nature - cesium - belongs to this group. He, like other alkaline similar substances, has little in common with more typical metals. Some sources claim that in fact, the softest metal is potassium, which is difficult to dispute or confirm, since neither one nor the other element exists on its own - being released as a result of a chemical reaction, they quickly oxidize or react.
The second group of metals - alkaline earth - is much closer to the main groups. The name "alkaline earth" comes from ancient times, when oxides were called "earths" because they have a loose crumbly structure. More or less familiar (in the everyday sense) properties are possessed by metals starting from the 3rd group. As the group number increases, the amount of metals decreases.
Dmitri Mendeleev was able to create a unique table of chemical elements, the main advantage of which was periodicity. Metals and non-metals in the periodic table are arranged in such a way that their properties change in a periodic manner.
The periodic system was compiled by Dmitri Mendeleev in the second half of the 19th century. The discovery not only made it possible to simplify the work of chemists, it was able to combine in itself both in unified system all discovered chemicals, and predict future discoveries.
The creation of this structured system is priceless 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 ready system dreamed of a scientist in a dream.
In an interview with one journalist, the scientist explained that he had been working on it for 25 years and that he dreamed about it was quite natural, but this does not mean that all the answers came in a 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 the system, each next element is different from the previous one. large quantity electrons in the nucleus, i.e. the charge of the nucleus 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 repeat 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. AT full period(i.e. the remaining four) 18 chemical representatives each.
In the group are chemical compounds with the same higher , i.e. they have the same electronic structure. A total of 18 groups are represented in the system ( 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 facilitate the search, 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.
In chemistry, three types of tables are used:
- Short - actinides and lanthanides are taken out of the boundaries of the main field, and 4 and all subsequent periods occupy 2 lines each.
- Long - in it actinides and lanthanides are taken out of the boundary of the main field.
- Extra long - each period occupies exactly 1 line.
The main one is considered to be the periodic table, which was adopted and officially confirmed, but for convenience, the short version is more often used. Metals and non-metals in the periodic table are arranged according to strict rules that make it easier to work with.
Metals in the periodic table
In the Mendeleev system, alloys have a predominant number and their list is very large - they start with Boron (B) and end with polonium (Po) (the exceptions are germanium (Ge) and antimony (Sb)). This group has characteristics, they are divided into groups, but their properties are heterogeneous. Their characteristic features:
- plastic;
- electrical conductivity;
- shine;
- easy return of electrons;
- ductility;
- thermal conductivity;
- hardness (except mercury).
Due to the different chemical and physical essence, the properties can 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 belongs to this group.
In its normal state, it is liquid and without a crystal lattice, which plays key role in alloys. Only chemical characteristics make mercury related 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 fractions of a second, and some do not occur in nature at all - they were created in artificial conditions laboratories. Each of the metal groups in the system has its own name and features that distinguish them from other groups.
However, their differences are quite significant. In the periodic system, all metals are arranged according to the number of electrons in the nucleus, i.e. by increasing atomic mass. At the same time, they are characterized by a periodic change characteristic properties. Because of this, they are not placed neatly in the table, but may be incorrect.
In the first group of alkalis, there are no substances that would be found in pure form in nature - they can only be in the composition of various compounds.
How to distinguish metal from non-metal?
How to determine the metal in the compound? There is an easy way to determine, but for this you need to have a ruler and a periodic table. To determine you need:
- Conduct conditional line at the junctions of elements from Bor to Polonium (possibly up to Astatine).
- All materials that will be on the left of the line and in the side subgroups are metal.
- 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 works only in a long table. The method can be used as a cheat sheet, but in order to accurately determine the substance, you should remember a list of all non-metals. How many are there? Few - only 22 substances.
In any case, to determine the nature of a substance, it is necessary to consider it separately. The elements will be easy if you know their properties. It is important to remember that all metals:
- At room temperature they are solid except for mercury. At the same time, they shine and conduct electricity well.
- They have on external level nucleus is a smaller number of atoms.
- Consist of a crystal lattice (except mercury), and all other elements have a molecular or ionic structure.
- In the periodic table, all non-metals are red, metals are black and green.
- If you move from left to right in a period, then the charge of the nucleus of matter will increase.
- Some substances have weak properties, but they still have characteristic features. Such elements belong to semimetals, such as Polonium or Antimony, they are usually located on the border of 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 you move in the table from top to bottom, they become stronger non-metallic properties substances, since there are elements that have distant outer shells. Their nucleus is separated from the electrons and therefore they are attracted weaker.
Useful video
Summing up
It will be easy to distinguish elements if you know the basic principles for the formation of the periodic table and the properties of metals. It will also be useful to memorize the list of the remaining 22 elements. But we must not forget that any element in the compound should be considered separately, not taking into account its bonds with other substances.
