The position of non-metals in the periodic table features. Nonmetals

All currently known chemical elements have a common "house" - the periodic system. However, they are not located there as necessary, but in a strict order, a certain sequence. One of the main criteria by which all atoms are classified are characteristics.

Non-metals and representatives of metallic elements are the basis on which not only their division within the table is based, but also the scope of human application. Let's take a closer look at non-metals and their characteristics.

Position in the periodic system

If we consider the system of chemical elements as a whole, then we can determine the location of the non-metals as follows:

1. Top right corner.
2. Above the conventional boundary diagonal from boron to astatine.
3. The main subgroups are from group IV-VIII.

Obviously, their number is clearly inferior to that of metals. In terms of numbers, this will be approximately 25/85. However, this fact does not in the least diminish their significance and importance. Moreover, the physical properties of non-metals are much more diverse than those of their "opponents".

Varieties of simple compounds of non-metals

Several basic categories are defined, which include all known elements under consideration. Physical properties- non-metals - allow you to divide them into:

• solid;
• gaseous;
• liquid.

At the same time, there is a special group of elements - noble gases. According to their characteristics, they do not belong to any of the designated categories.

Gaseous non-metals

There are many of them. These include the following simple substances, how:

• oxygen;
• nitrogen;
• halogens chlorine and fluorine;
• hydrogen;
• white phosphorus;
• ozone.

However, this is possible provided standard parameters environment. Crystal cell of these representatives - molecular type chemical bond in molecules - covalent non-polar. The physical properties of the group are similar. They possess:

• compressibility;
• the ability of boundless mixing with each other;
• expandability;
• fill the entire volume of the vessel.

Among the listed substances, two are poisonous - chlorine and Very dangerous, asphyxiant compounds. At the same time, chlorine is a yellow-green gas, phosphorus is white, easily flammable in air.

Oxygen and ozone are good oxidants. The first is a constant component of the air necessary for the life of most organisms. The second is formed after a thunderstorm when electrical discharges of lightning act on oxygen in the air. Has a pleasant scent of freshness.

Liquid non-metals

The physical properties of non-metals of this group can be described by characterizing only one substance - bromine. Since only he is a liquid at normal conditions among all representatives of the considered group of elements.

It is a dark brown liquid, quite heavy, which is the strongest poison. Even bromine vapors can cause difficult, non-healing long time ulcers on the hands. Its smell is very unpleasant, for which the element got its name (in translation bromos - fetid).

In terms of its chemical characteristics, bromine is an oxidizing agent for metals and a reducing agent for stronger non-metals than itself.

Despite these features, bromine ions must be present in the human body. Without it, diseases associated with hormonal disorders occur.

Solid representatives

Most non-metals belong to simple substances in this category. This is:

• all carbon;
• red and black phosphorus;
• sulfur;
• silicon;
• arsenic;
• one of the modifications of tin.

All of them have fairly hard, but fragile substances. Black phosphorus is a greasy dry compound. Red is a pasty mass.

The hardest of all these substances is diamond - a type of carbon. The physical and chemical properties of non-metals in this group are very different, since some of them are located far from each other in the table. This means that the degree of oxidation, the displayed chemical activity, the nature of the compounds - all these indicators will vary.

An interesting non-metal in the solid state is iodine. Its crystals shine on a cut, thus showing a similarity to metals. This is not surprising, because it is located almost on the border with them. This substance also has special property- sublimation. When heated, iodine turns into a gaseous state, bypassing the liquid. Its pairs have a bright purple saturated color.

Physical properties of non-metals: table

To make it easier to identify what non-metals are, it is better to build a summary table. It will show what are the general physical properties of non-metals, and what are their differences.

Obviously, differences rather than similarities prevail in the physical properties of non-metals. If for metals several characteristics can be distinguished, under which each of them will fall, then this is impossible for the elements we have considered.

1. Position of metals in the table of elements

Metals are located mainly in the left and bottom parts of the PSCE. These include:

2. The structure of metal atoms

Metal atoms at the outer energy level usually have 1-3 electrons. Their atoms have a large radius and easily donate valence electrons, i.e. show restorative properties.

3. Physical properties of metals

Metallic bond - This is a bond that is carried out by free electrons between cations in a metal crystal lattice.

4. Obtaining metals

1. Reduction of metals from oxides with coal or carbon monoxide

Me x O y + C = CO 2 + Me or Me x O y + CO = CO 2 + Me

2. Roasting of sulfides with subsequent reduction

Stage 1 - Me x S y + O 2 = Me x O y + SO 2

Stage 2 -Mе x O y + C = CO 2 + Me or Me x O y + CO = CO 2 + Me

3 Aluminothermy (recovery with a more active metal)

Me x O y + Al = Al 2 O 3 + Me

4. Hydrogen therapy - for obtaining high purity metals

Me x O y + H 2 = H 2 O + Me

5. Recovery of metals by electric current (electrolysis)

1) Alkali and alkaline earth metals obtained in industry by electrolysis molten salts (chlorides):

2NaCl - melt, electr. current. → 2 Na + Cl 2

CaCl 2 - melt, electr. current.→ Ca + Cl 2

melts of hydroxides:

4NaOH - melt, electr. current.→ 4 Na + O 2 + 2 H 2 O

2) Aluminum in industry obtained as a result of electrolysis melt aluminum oxide I in cryolite Na 3 AlF 6 (from bauxite):

2Al 2 O 3 - melt in cryolite, electr. current.→ 4 Al + 3 O 2

3) Electrolysis aqueous solutions salts use to obtain metals of medium activity and inactive:

2CuSO 4 + 2H 2 O - solution, electr. current.→ 2 Cu + O 2 + 2 H 2 SO 4

5. Finding metals in nature

The most widespread metal in the earth's crust is aluminum. Metals are found both in compounds and in free form.

1. Active - in the form of salts (sulfates, nitrates, chlorides, carbonates)

2. Average activity - in the form of oxides, sulfides ( Fe 3 O 4, FeS 2)

CHEMICAL PROPERTIES OF METALS

The general chemical properties of metals are presented in the table:

TASKS FOR ANCHORING

# 1. Finish Equations feasible reactions, name the reaction products

Li + H 2 O =

Cu + H 2 O =

Al + H 2 O =

Ba + H 2 O =

Mg + H 2 O =

Ca + HCl =

Na + H 2 SO 4 (K) =

Al + H 2 S =

Ca + H 3 PO 4 =

HCl + Zn =

H 2 SO 4 (k) + Cu =

H 2 S + Mg =

HCl + Cu =

HNO 3 (K) + С u =

H 2 S + Pt =

H 3 PO 4 + Fe =

HNO 3 (p) + Na =

No. 2. Finish the CCM, arrange the coefficients using the electronic balance method, indicate the oxidizing agent (reducing agent):

Al + O 2 =

Li + H 2 O =

Na + HNO 3 (k) =

Mg + Pb (NO 3) 2 =

Ni + HCl =

No. 3. Insert missing characters (<, >or =)

No. 4. Finish the CCM, arrange the coefficients using the electronic balance method, indicate the oxidizing agent (reducing agent):

K + O 2 =

Mg + H 2 O =

Pb + HNO 3 (p) =

Fe + CuCl 2 =

Zn + H 2 SO 4 (p) =

Zn + H 2 SO 4 (k) =

No. 5. Solve test tasks

ELEMENT PROPERTIES AND PERIODIC SYSTEM

All elements in the Periodic Table are conventionally divided into metals and non-metals. Non-metallic elements include:

Not, Ne, Ar, Kr, Xe, Rn, F, C1, Br, I, At, O, S, Se. Te, N, P, As, C, Si, B, H

All other elements are considered metallic.

Simple substances (elements in free form) are also subdivided into metals and non-metals, based on their physical- chemical properties Oh... So, in terms of physical properties, for example, electronic conductivity, boron is a non-metal, and copper is a metal, although exceptions are possible (graphite).

In the Periodic Table, non-metals are elements of the main groups (A-groups), starting with IIIA group (boron); other elements of A-groups and all elements of B-groups are metals. In the main groups, the metallic properties are more pronounced for heavier elements, and only metals are included in the 1A-group, and only non-metals in the VPA and VIIIA groups.

In the main groups, the metallic properties of the elements increase, and the non-metallic properties decrease with an increase in the serial number of the element.

In periods for elements of the main groups, the metallic properties decrease, and the non-metallic properties increase with an increase in the serial number of the element.

Hence it follows that the most typical is not metal element is fluorine, the most typical metallic element is francium.

In the Periodic Table, natural boundaries are clearly visible, relative to which a change in the properties of elements is observed. Group 1A contains typical metals, elements of group VIIIA (noble gases) are typical non-metals, intermediate groups include non-metals "at the top" of the table of elements and metals "at the bottom" of the table of elements. Another boundary between metals and non-metals corresponds to the elements Be - A1-Ge - Sb - Po (diagonal boundary). The elements of this border itself and those adjacent to it have both metallic and non-metallic properties; amphoteric behavior is characteristic of these elements. Simple substances of these elements can occur both in the form of metallic and non-metallic modifications (allotropic forms).

The ionization energy of their atoms can be taken as a measure of the metallic and non-metallic character of the elements. Ionization energy is the energy that must be expended to completely remove one electron from an atom. Usually, metals have a relatively low ionization energy (496 kJ / mol for Na, 503 kJ / mol for Ba), and non-metals have a high ionization energy (1680 kJ / mol for F, 1401 kJ / mol for N). The atoms of elements exhibiting amphoteric behavior (Be, A1, Ge, Sb, Po, etc.) correspond to intermediate values ionization energies (762 kJ / mol for Ge, 833 kJ / mol for Sb), and the highest values ​​for noble gases (2080 kJ / mol for Ne, 2372 kJ / mol for He). Within the group of the Periodic Table, the values ​​of the ionization energy of atoms decrease with an increase in the ordinal number of the element, i.e., with an increase in the size of the atoms. Electro-positive and electronegative elements. In accordance with the tendency of atoms of elements to form positive and negative monatomic ions, electropositive and electronegative elements are distinguished.

Atoms of electronegative elements have a high electron affinity. The atoms of these elements hold their own electrons very tightly and tend to accept additional electrons in chemical reactions. Atoms of electropositive elements have a low electron affinity. The atoms of such elements weakly retain their own electrons and tend to lose these electrons in chemical reactions.

The most electrically positive elements are typical metals (group 1A elements), and the most electronegative elements are typical non-metals (group VPA elements).

The electropositive nature of the elements increases with the transition from top to bottom within the main groups and decreases with the transition from left to right within the periods. The electronegative character of the elements decreases when going from top to bottom within the main groups and increases when going from left to right within the periods.

The answer should start with characterizing the position of non-metals in periodic system: if we draw an imaginary diagonal from beryllium Be to astatine At, then non-metals will be located in the main subgroups above the diagonal (i.e., in the upper right corner). Non-metals also include hydrogen H and inert gases.

Further, it is important to note that for the general characteristics of non-metals, it is necessary to pay attention to the structure of their atoms, how electrons are distributed over the electronic layers, and how many electrons are in the outer electronic layer. It is possible to give the structure of carbon atoms C, nitrogen N, oxygen O, fluorine F. This will make it possible to conclude that as the ordinal numbers of atoms of elements increase and electrons accumulate on the outer layer, non-metals of one period increase the ability to receive electrons from other atoms to their the outer layer, that is, the non-metallic properties of the elements increase in periods.

Considering the change in the properties of non-metals when moving along the group, it should be noted that they weaken. This is due to an increase in the distance from the nucleus to the outer layer, and, consequently, a decrease in the ability of the nucleus to attract electrons to itself from other atoms. To confirm this conclusion, consider the VI group. At the beginning of it there is oxygen O - a typical non-metal, and the group ends with polonium Po, which has the properties of a metal.

Next, you should go on to consider the physical properties of non-metals. It should be noted that simple substances - non-metals can have both atomic (Si, B) and molecular (H2, N2, Br2) structures. Therefore, among non-metals there are gases (O2, C12), liquids (Br2), solids (C, 12). Most non-metals are not electrically conductive, have low thermal conductivity, and solids are not plastic.

Turning to the characterization of chemical properties, it should be noted that the process of accepting electrons is more typical for non-metals. This is the difference between the chemical properties of non-metals and the chemical properties of metals. This position can be confirmed by the interaction of non-metals with simple substances. In this case, one should write down the equations of the corresponding chemical reactions and explain their essence in terms of oxidation - reduction processes. It should be noted that non-metals can exhibit the properties of both oxidizing and reducing agents. Here are some examples.

It can be added that some non-metals can react with complex substances (oxides, acids, salts). The student leads the following equations at will.