Alkali elements in the periodic table

3 parts: Structure of the table Element designations Calculating the number of neutrons by atomic mass If you find the periodic table difficult to understand, you are not alone! Although it can be difficult to understand its principles, learning how to use it will help you when studying science. First, study the structure of the table and what information you can learn from it about each chemical element. Then you can begin to study 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 Chemical properties the elements also have a certain sequence (they say that this idea came to him in a dream). The result of the scientist’s wonderful dreams was the Periodic Table of Chemical Elements, in which D.I. Mendeleev built chemical elements Ascending atomic mass. In the 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 easily lose electrons, 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 are also important for the production of almost all objects. There is metal even in human body. When you look at a multivitamin's nutritional label, you'll see dozens of compounds listed.

Determination of metals and non-metals in the periodic table.

How to determine a metal or a non-metal In the Natural Sciences section, the question is how to determine from the periodic table which is a metal and which is a non-metal? given by the author Proscenium the best answer 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

Non-metals | Position in the periodic table

They are characterized by the properties of both metals and non-metals. Depending on their density, metals are divided into light (density 0.53 × 5 g/cm?) and heavy (5 × 22.5 g/cm?). Between metals and nonmetals there are semimetals (metalloids). For example, in group IA(1), 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.

Table of groups of metals and non-metals in the periodic table of Mendeleev: what is it and how to determine the softest element

The periodic table of chemical elements was compiled by D.I. Mendeleev in the second half of the 19th century. What is it and what is it for? It unites all chemical elements in order of increasing atomic weight, and they are all arranged in such a way that their properties change in a periodic manner.

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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

Nonmetals are elements from the 14th to 16th groups of the periodic table. They almost do not conduct electricity and heat. Non-metals are very brittle and practically resistant to bending or any other deformation. They can exist in 2 of 3 states of matter at room temperature: gas (eg oxygen) and solid (eg 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 cyclicality 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. Modern scientists also pay attention to signs of repetition. For example, Carl Linnaeus was able to build a system of living beings based on phenotypic similarity.

How to Find out a Metal or Non-Metal in the Periodic Table?

I know about “draw 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 exceptions or what? Second question: Those elements that are on the line have the properties of both metals and non-metals. Do they form a metallic bond?

Nature has a certain cyclicality and repetition in its manifestations. Ancient Greek scientists also paid attention to this when they tried to decompose the nature of things into their components: elements, geometric figures and even atoms. Modern scientists also pay attention to signs of repetition. For example, Carl Linnaeus was able to build a system of living beings based on phenotypic similarity.

For a long time chemistry as a science remained without a system that could organize the great variety of discovered substances. The knowledge of ancient alchemists provided rich material for building such a system. Many scientists have made attempts to build a harmonious scheme, but all attempts were in vain. This was the case until 1869, when the great Russian chemist Dmitry Ivanovich Mendeleev presented the world with his brainchild - the periodic table of chemical elements. They say that a scientist dreamed of the table. In his dream, he saw a table lined up in the shape of a snake and wrapped around his feet. The reliability of this fact is doubtful, but be that as it may, it was a real breakthrough in science.

Mendeleev arranged the elements in order of increasing atomic mass. This principle is still relevant today, however, now it is based on the number of protons and neutrons in the nucleus.

Metals and their distinctive properties

All chemical elements can be fairly roughly divided into metals and non-metals. What makes them different from each other? How to distinguish a metal from a non-metal?

Of the 118 discovered substances, 94 belong to the group of metals. The group is represented by various subgroups:

What characteristics are common to all metals?

1. All metals at room temperature are solids. This is true for all elements except mercury, which is solid down to minus 39 degrees Celsius. In room conditions, mercury is a liquid.
2. Most of the elements in this group have a fairly high melting point. For example, Tungsten melts at a temperature of 3410 degrees Celsius. For this reason, it is used to make filament in incandescent lamps.
3. All metals are ductile. This manifests itself in the fact that the crystal lattice of the metal allows the atoms to move. As a result, metals can bend without physical deformation and can be forged. Copper, gold and silver are particularly ductile. That is why historically they were the first metals processed by man. Then he learned how to process iron.
4. All metals conduct electricity very well, which is again due to the structure of the metal crystal lattice, which has mobile electrons. Among other things, these elements conduct heat very easily.
5. And, finally, all metals have a characteristic, incomparable metallic luster. The color is most often grayish with a blue tint. Au, Cu or Cs have yellow and red tints.

Don't miss: mechanism of education, specific examples.

Nonmetals

All nonmetals are located in the upper right corner of the periodic table along a diagonal that can be drawn from hydrogen to astatine and radon. By the way, hydrogen can also exhibit metallic properties under certain conditions.

The main difference from metals is the structure of the crystal lattice. While metals have a metallic crystal lattice, non-metals can have an atomic or molecular lattice. Molecular lattice possess some gases - oxygen, chlorine, sulfur, nitrogen. Substances with an atomic lattice have a solid state of aggregation and a relatively high melting point.

The physical properties of non-metals are quite diverse; non-metals can be solid (iodine, carbon, sulfur, phosphorus), liquid (only bromine), gaseous (fluorine, chlorine, nitrogen, oxygen, hydrogen) substances with a completely different color. State of aggregation may change under the influence of temperature.

From a chemical point of view, nonmetals can act as oxidizing and reducing agents. Nonmetals can interact with each other and with metals. Oxygen, for example, acts as an oxidizing agent with all substances, but with fluorine it acts as a reducing agent.

Allotropy

Another amazing property of non-metals is a phenomenon called allotropy - the modification of substances leading to different allotropic modifications the same chemical element. The word “allotropy” can be translated from Greek as “another property”. The way it is.

Let's take a closer look at the example of a list of some simple substances:

Other substances also have modifications– sulfur, selenium, boron, arsenic, boron, silicon, antimony. At different temperatures, many metals also exhibit these properties.

Of course, the division of all simple substances into groups of metals and non-metals is quite arbitrary. This division makes it easier to understand the properties of chemical substances and creates the illusion of their separation into separate substances. Like everything in the world, this division is relative and depends on external factors environment– pressure, temperature, light, etc.

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 open chemical substances, 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 a total of 7 periods in the system, each next element different from the previous one big amount 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, i.e. they have the same electronic structure. In total, the system contains 18 groups ( full version), each of which begins with an 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 key role in alloys. Only chemical characteristics mercury is 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 a fraction of a second, and some are not found 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 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 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.

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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.

There are many repeating sequences in nature:

• Seasons;
• Times of Day;
• days of the week…

In the mid-19th century, D.I. Mendeleev noticed that the chemical properties of elements also have a certain sequence (they say that this idea came to him in a dream). The result of the scientist’s wonderful dreams was the Periodic Table of Chemical Elements, in which D.I. Mendeleev arranged chemical elements in order of increasing atomic mass. In the 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).

The atomic number is shown above the symbol of a chemical element, below the symbol is its atomic mass (the sum of protons and neutrons). Please note that the atomic mass of some elements is not a whole number! Remember isotopes! Atomic mass is the weighted average of all isotopes of an element found in nature under natural conditions.

Below the table are lanthanides and actinides.

Metals, non-metals, metalloids

Located in the Periodic Table to the left of the stepped diagonal line that begins with Boron (B) and ends with polonium (Po) (the exceptions are germanium (Ge) and antimony (Sb). It is easy to see that metals occupy most Periodic table. Basic properties of metals: solid (except mercury); shine; good electrical and thermal conductors; plastic; malleable; give up electrons easily.

The elements located to the right of the B-Po stepped diagonal are called non-metals. The properties of non-metals are exactly the opposite of those of metals: poor conductors of heat and electricity; fragile; non-malleable; non-plastic; usually accept electrons.

Metalloids

Between metals and non-metals there are semimetals(metalloids). They are characterized by the properties of both metals and non-metals. Semimetals have found their main application in industry in the production of semiconductors, without which not a single modern microcircuit or microprocessor is conceivable.

Periods and groups

As mentioned above, the periodic table consists of seven periods. In each period, the atomic numbers of elements increase from left to right.

The properties of elements change sequentially in periods: thus sodium (Na) and magnesium (Mg), located at the beginning of the third period, give up electrons (Na gives up one electron: 1s 2 2s 2 2p 6 3s 1 ; Mg gives up two electrons: 1s 2 2s 2 2p 6 3s 2). But chlorine (Cl), located at the end of the period, takes one element: 1s 2 2s 2 2p 6 3s 2 3p 5.

In groups, on the contrary, all elements have the same properties. For example, in group IA(1), all elements from lithium (Li) to francium (Fr) donate one electron. And all elements of group VIIA(17) take one element.

Some groups are so important that they have received special names. These groups are discussed below.

Group IA(1). Atoms of elements of this group have only one electron in their outer electron layer, so they easily give up one electron.

The most important alkali metals- sodium (Na) and potassium (K), as they play important role in the process of human life and are included in the composition of salts.

Electronic configurations:

• Li- 1s 2 2s 1 ;
• Na- 1s 2 2s 2 2p 6 3s 1 ;
• K- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1

Group IIA(2). Atoms of elements of this group have two electrons in their outer electron layer, which they also give up during chemical reactions. The most important element is calcium (Ca) - the basis of bones and teeth.

Electronic configurations:

• Be- 1s 2 2s 2 ;
• Mg- 1s 2 2s 2 2p 6 3s 2 ;
• Ca- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2

Group VIIA(17). Atoms of elements of this group usually receive one electron each, because There are five elements on the outer electronic layer and one electron is just missing from the “complete set”.

The most well-known elements of this group: chlorine (Cl) - is part of salt and bleach; Iodine (I) is an element that plays an important role in the activity of the human thyroid gland.

Electronic Configuration:

• F- 1s 2 2s 2 2p 5 ;
• Cl- 1s 2 2s 2 2p 6 3s 2 3p 5 ;
• Br- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5

Group VIII(18). Atoms of elements of this group have a fully “complete” outer electron layer. Therefore, they “don’t” need to accept electrons. And they “don’t want” to give them away. Hence, elements of this group are very “reluctant” to join chemical reactions. For a long time it was believed that they do not react at all (hence the name “inert”, i.e. “inactive”). But chemist Neil Bartlett discovered that some of these gases can still react with other elements under certain conditions.

Electronic configurations:

• Ne- 1s 2 2s 2 2p 6 ;
• Ar- 1s 2 2s 2 2p 6 3s 2 3p 6 ;
• Kr- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6

Valence elements in groups

It is easy to notice that within each group the elements are similar to each other in their valence electrons (electrons of s and p orbitals located on the outer energy level).

Alkali metals have 1 valence electron:

• Li- 1s 2 2s 1 ;
• Na- 1s 2 2s 2 2p 6 3s 1 ;
• K- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1

Alkaline earth metals have 2 valence electrons:

• Be- 1s 2 2s 2 ;
• Mg- 1s 2 2s 2 2p 6 3s 2 ;
• Ca- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2

Halogens have 7 valence electrons:

• F- 1s 2 2s 2 2p 5 ;
• Cl- 1s 2 2s 2 2p 6 3s 2 3p 5 ;
• Br- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5

Inert gases have 8 valence electrons:

• Ne- 1s 2 2s 2 2p 6 ;
• Ar- 1s 2 2s 2 2p 6 3s 2 3p 6 ;
• Kr- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6

For more information, see the article Valency and the Table of Electronic Configurations of Atoms of Chemical Elements by Period.

Let us now turn our attention to the elements located in groups with symbols IN. They are located in the center of the periodic table and are called transition metals.

A distinctive feature of these elements is the presence in the atoms of electrons that fill d-orbitals:

1. Sc- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 1 ;
2. Ti- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 2

Separately from the main table are located lanthanides And actinides- these are the so-called internal transition metals. In the atoms of these elements, electrons fill f-orbitals:

1. Ce- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 4d 10 5s 2 5p 6 4f 1 5d 1 6s 2 ;
2. Th- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 4d 10 5s 2 5p 6 4f 14 5d 10 6s 2 6p 6 6d 2 7s 2

The properties of chemical elements make it possible to combine them into appropriate groups. On this principle, the 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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Mendeleev's periodic table

The periodic table of chemical elements was compiled by D.I. Mendeleev in the second half of the 19th century. What is it and what is it for? It unites all chemical elements in order of increasing atomic weight, and they are all arranged in such a way that their properties change in a periodic manner.

Mendeleev's periodic system brought together unified system all existing elements that were previously considered simply separate substances.

Based on its study, new chemical substances were predicted and subsequently synthesized. The significance of this discovery for science cannot be overestimated, it was significantly 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 called “short”, “long” and “extra-long” ». The main table is considered to be a long table, it officially approved. The difference between them is the arrangement of elements and the length of periods.

What is a period

The system contains 7 periods. They are presented graphically as horizontal lines. In this case, a period can have one or two lines, called rows. Each subsequent element differs from the previous one by increasing the nuclear charge (number of electrons) by one.

To keep it simple, a period is a horizontal row of the periodic table. Each of them begins with 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

A group is a vertical column, containing elements with the same electronic structure or, more simply, with the same higher value. The officially approved long table contains 18 groups, which begin with alkali metals and end with noble gases.

Each group has its own name, making it easier to search or classify elements. Metallic properties are enhanced, regardless of the element, from top to bottom. This is due to an increase in the number of atomic orbits - the more there are, the weaker the electronic bonds, 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 the physical sense, while others can exist only for a fraction of a second and are absolutely not found in nature (at least on the planet), since they were created, or rather, calculated and confirmed in laboratory conditions, artificially. Each group has its own characteristics, the name is quite noticeably different from the others. This difference is especially pronounced in the first group.

Position of metals

What is the position of metals in the periodic table? Elements are arranged by increasing atomic mass, or number of electrons and protons. Their properties change periodically, so there is no neat placement on a one-to-one basis in the table. How to identify metals, and is it possible to do this using the periodic table? In order to simplify the question, a special technique was invented: conditionally, a diagonal line is drawn from Bor to Polonius (or to Astatus) at the junctions of the elements. Those on the left are metals, those on the right are non-metals. This would be very simple and cool, but there are exceptions - Germanium and Antimony.

This “methodology” is a kind of cheat sheet; it was invented only to simplify the memorization process. For a more accurate representation, it should be remembered that the list of nonmetals is only 22 elements, therefore, answering the question, 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 shine.
• Electrical conductivity.
• High thermal conductivity.
• All except mercury are in a solid state.

It should be understood that the properties of metals vary greatly regarding 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. Under normal conditions, it is in a liquid state and does not have a crystal lattice, the presence of which other metals owe their properties to. The properties of the latter in this case are conditional; mercury is similar to them to a greater extent in its chemical characteristics.

Interesting! Elements of the first group, alkali metals, are not found in pure form, but are found in various compounds.

The softest metal existing in nature, cesium, belongs to this group. It, like other alkaline 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 - when released as a result of a chemical reaction, they quickly oxidize or react.

The second group of metals - alkaline earth metals - are much closer to the main groups. The name "alkaline earth" comes from ancient times, when oxides were called "earths" because they had a loose, crumbly structure. Metals starting from group 3 have more or less familiar (in the everyday sense) properties. As the group number increases, the amount of metals decreases