Nonmetals. general characteristics

Part I

1. The position of non-metals (NM) in the Periodic system.

On the diagonal of B-At and above it, non-metals are located in 6 groups. In total, out of 114 elements, 22 belong to NM.

2. Features of the structure of NM atoms:
1) small atomic radius
2) the number of electrons per external level 4-8.

3. NM have the property of allotropy- the phenomenon of the existence of one chem. element in the form of 2 or more simple substances.

4. Fill in the table "Causes of allotropy".

5. NM - simple substances and free atoms exhibit both oxidizing and reducing properties.

Fill in the table "Chemical properties of non-metals".

Write down the reaction equations, consider them in the light of oxidation-reduction processes.

6. Complete the table "Composition of air".

Part II

1. Write down the order in which its main components “boil away” from liquid air.
1) nitrogen N2 (tk) \u003d -196 ⁰С
2) argon Ar (tк) = -186 ⁰С
3) oxygen O2 (tk) = -183 ⁰С

2. The molar volume of air has a mass of 29 g. A value showing how many times molar mass any gas heavier than M air is called relative density this gas in air and is denoted by Dair.
Find Dair for:

3. What volume of each of the three main components of air can be obtained from 500 m3 of air?

4. Complete the scheme "The role of air in nature and human life."

5. Correlate the gas collected by the air displacement method with the location of the vessel.

6. Select the phenomena that are caused by the presence of it in the air constituent parts: 1) random; 2) variables. From the letters corresponding to the correct answers, you will make names chemical elements– non-metals:
1) nitrogen; 2) sulfur.
a) smog - 1
b) greenhouse effect - 2
c) influenza - 1
d) ozone holes - 2
e) allergy to flowering plants - 1
f) fog - 2
g) acid rain - 1
h) fresh air in pine forests - 2

Non-metals are elements that differ significantly in physical and chemical properties from metals. The reason for their differences could be explained in detail only in late XIX century after the discovery electronic structure atom. What is the peculiarity of non-metals? What qualities are characteristic of their day? Let's figure it out.

Non-metals - what is it?

The approach to separating elements into metals and non-metals has long existed in the scientific community. The first elements in the periodic table of Mendeleev usually include 94 elements. Mendeleev's non-metals include 22 elements. In they occupy the upper right corner.

In their free form, non-metals are simple substances, main feature which is the absence of characteristic metallic properties. They can be in all states of aggregation. So, iodine, phosphorus, sulfur, carbon are found in the form of solid substances. The gaseous state is characteristic of oxygen, nitrogen, fluorine, etc. Only bromine is a liquid.

In nature, non-metal elements can exist both in the form of simple substances and in the form of compounds. Sulfur, nitrogen, oxygen are found in unbound form. In compounds, they form borates, phosphates, etc. In this form, they are present in minerals, water, rocks.

Difference from metals

Non-metals are elements that are different from metals appearance, structure and chemical properties. They possess a large number unpaired electrons at the external level, which means they are more active in oxidative reactions and more easily attach additional electrons to themselves.

A characteristic difference between the elements is observed in the structure of the crystal lattice. In metals, it is metallic. In non-metals, it can be of two types: atomic and molecular. The atomic lattice gives substances hardness and increases the melting point; it is characteristic of silicon, boron, and germanium. Chlorine, sulfur, oxygen have a molecular lattice. It gives them volatility and a little hardness.

The internal structure of elements determines their physical properties. Metals have a characteristic luster, good conductivity of current and heat. They are hard, ductile, malleable, have a small range of colors (black, shades of gray, sometimes yellowish).

Non-metals are liquid, gaseous or non-lustrous and malleable. Their colors vary greatly and can be red, black, gray, yellow, etc. Almost all non-metals are poor conductors of current (except carbon) and heat (except black phosphorus and carbon).

Chemical properties of non-metals

AT chemical reactions non-metals can act as both oxidizing and reducing agents. When interacting with metals, they take on electrons, thus showing oxidizing properties.

Interacting with other non-metals, they behave differently. In such reactions, the less electronegative element acts as a reducing agent, while the more electronegative element acts as an oxidizing agent.

With oxygen, almost all (except fluorine) non-metals act as reducing agents. When interacting with hydrogen, many are oxidizing agents, subsequently forming volatile compounds.

Some non-metal elements have the ability to form several simple substances or modifications. This phenomenon is called allotropy. For example, carbon exists in the form of graphite, diamond, carbine, and other modifications. Oxygen has two of them - ozone and oxygen itself. Phosphorus comes in red, black, white, and metallic.

Nonmetals in nature

Non-metals are found everywhere in varying amounts. They are part of the earth's crust, are part of the atmosphere, hydrosphere, are present in the universe and in living organisms. AT outer space The most common are hydrogen and helium.

On Earth, the situation is quite different. The most important constituents of the earth's crust are oxygen and silicon. They make up more than 75% of its mass. And here least amount accounts for iodine and bromine.

In the composition of sea water, oxygen accounts for 85.80%, and hydrogen - 10.67%. Its composition also includes chlorine, sulfur, boron, bromine, carbon, fluorine and silicon. Nitrogen (78%) and oxygen (21%) dominate in the composition of the atmosphere.

Non-metals such as carbon, hydrogen, phosphorus, sulfur, oxygen and nitrogen are important organic substances. They support the vital activity of all living beings on our planet, including humans.

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

Non-metals and representatives metal elements- this is 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 position of non-metals as follows:

1. Upper right corner.
2. Above the conditional boundary diagonal from boron to astatine.
3. Main subgroups with IV-VIII group.

Obviously, their number is clearly inferior to that of metals. In terms of numerical ratio, this will be approximately 25/85. However given fact does not in any way diminish their significance and importance. At the same time, the physical properties of non-metals are much more diverse than those of their "opponents".

Varieties of simple compounds of non-metals

Several main categories are defined to which all known elements under consideration belong. Physical Properties- non-metals - allow you to divide them into:

• hard;
• 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 enough of those. These include such simple substances as:

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

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

• compressibility;
• the ability to intermingle without limit;
• extensibility;
• fill the entire volume of the vessel.

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

Oxygen and ozone are good oxidizers. The first is a constant component of air, necessary for the life of most organisms. The second is formed after a thunderstorm under the action of electrical discharges of lightning on oxygen in the air. Has a pleasant fresh scent.

Liquid non-metals

The physical properties of non-metals of this group can be described by characterizing only one substance - bromine. Since only it is a liquid under 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 complex, non-healing long time ulcers on the hands. Its smell is very unpleasant, for which the element got its name (in translation, bromos - fetid).

According to 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

The majority of 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 solid, but brittle substances. Black phosphorus is a dry compound that is greasy to the touch. Red is a pasty mass.

The hardest of all these substances is diamond, a type of carbon. Physical and Chemical properties nonmetals of 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 chemical activity exhibited, the nature of the compounds - all these indicators will vary.

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

Physical properties of non-metals: table

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

physical property	Example of a non-metal
under normal conditions	All three are characteristic: solid (sulfur, carbon, silicon and others), gaseous (for example, halogens), liquid (bromine)
Electrical and thermal conductivity	Not characteristic of anything other than carbon and black phosphorus
Coloring of a simple substance	Very varied. Example: bromine is red, sulfur is yellow, iodine crystals are dark purple, carbon in the form of graphite is dark gray, chlorine is yellow-green, and so on.
metallic luster	Characteristic only for crystalline iodine
Malleability and ductility	Completely missing. All solids- brittle, except for diamond and some forms of silicon

It is obvious that in the physical properties of non-metals differences prevail more than similarities. If for metals it is possible to distinguish several characteristics under which each of them will fall, then for the elements we have considered this is impossible.

1. The position of metals in the table of elements

Metals are located mainly in the left and lower part of the PSCE. These include:

2. The structure of metal atoms

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

3. Physical properties of metals

Change in the electrical conductivity of a metal during its heating and cooling

metal connection - this is the bond that free electrons carry out between cations in a metal crystal lattice.

4. Obtaining metals

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

Me x O y + C \u003d CO 2 + Me or Me x O y + CO \u003d CO 2 + Me

2. Sulfide roasting followed by reduction

1 stage - Me x S y + O 2 \u003d Me x O y + SO 2

Stage 2 -Me x O y + C \u003d CO 2 + Me or Me x O y + CO \u003d CO 2 + Me

3 Aluminothermy (recovery with a more active metal)

Me x O y + Al \u003d Al 2 O 3 + Me

4. Hydrothermy - to obtain high purity metals

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

5. Recovery of metals by electric current (electrolysis)

1) Alkaline and alkaline earth metals obtained in industry by electrolysis salt melts (chlorides):

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

CaCl 2 - melt, electr. current.→ Ca + Cl2

hydroxide melts:

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

2) Aluminum industrially produced by electrolysis aluminum oxide melt 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 of aqueous solutions of 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 common in earth's crust metal is aluminium. Metals are found both in compounds and in free form.

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

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

3. Noble - in free form ( Au, Pt, Ag)

CHEMICAL PROPERTIES OF METALS

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

TASKS FOR REINFORCEMENT

No. 1. Finish Equations practicable reactions name the reaction products

Li + H 2 O \u003d

Cu + H 2 O \u003d

Al + H 2 O \u003d

Ba + H 2 O =

Mg + H 2 O \u003d

Ca+HCl=

Na + H 2 SO 4 (K) \u003d

Al + H 2 S \u003d

Ca + H 3 PO 4 \u003d

HCl + Zn =

H 2 SO 4 (to) + Cu \u003d

H 2 S + Mg =

HCl + Cu =

HNO 3 (K) + C u =

H 2 S + Pt =

H 3 PO 4 + Fe =

HNO 3 (p)+ Na=

Fe + Pb(NO 3) 2 =

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

Al + O 2 \u003d

Li + H 2 O =

Na + HNO 3 (k) =

Mg + Pb (NO 3) 2 \u003d

Ni + HCl =

Ag + H 2 SO 4 (k) \u003d

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

Core charge	Li…Rb	Na…Al	Ca…K
Number of energy levels	Li…Rb	Na…Al	Ca…K
Number of outer electrons	Li…Rb	Na…Al	Ca…K
Atom radius	Li…Rb	Na…Al	Ca…K
Restorative properties	Li…Rb	Na…Al	Ca…K

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

K + O 2 \u003d

Mg + H 2 O \u003d

Pb + HNO 3 (p) =

Fe + CuCl 2 \u003d

Zn + H 2 SO 4 (p) \u003d

Zn + H 2 SO 4 (k) \u003d

No. 5. Solve test tasks

1.Select a group of elements that contains only metals: A) Al, As, P; B) Mg, Ca, Si; B) K, Ca, Pb 2. Select a group in which there are only simple substances - non-metals: A) K 2 O, SO 2, SiO 2; B) H 2 , Cl 2 , I 2 ; B )Ca, Ba, HCl; 3. Indicate what is common in the structure of K and Li atoms: A) 2 electrons on the last electron layer; B) 1 electron on the last electron layer; AT) the same number electronic layers. 4. Metal calcium exhibits properties: A) an oxidizing agent B) reducing agent; C) an oxidizing or reducing agent, depending on the conditions. 5. The metallic properties of sodium are weaker than those of - A) magnesium; B) potassium; C) lithium. 6. Inactive metals include: A) aluminum, copper, zinc; B) mercury, silver, copper; C) calcium, beryllium, silver. 7. What is the physical property is not common to all metals: A) electrical conductivity, B) thermal conductivity, C) solid state of aggregation under normal conditions, D) metallic luster

Part B. The answer to the tasks of this part is a set of letters that should be written down Set a match. With an increase in the ordinal number of the element in the main subgroup of group II Periodic system the properties of the elements and the substances they form change as follows: