Characteristics of calcium. Properties of calcium. Calcium Formula

Among all elements of the periodic system, several can be distinguished, without which not only various diseases develop in living organisms, but it is also impossible to live and grow normally. One such is calcium.

It is interesting that when it comes to this metal, as a simple substance, it does not have any good for a person, even harm. However, it is only necessary to mention the ions of Ca ²⁺ , as a mass of points immediately appear that characterize their important significance.

The position of calcium in the periodic table

The characteristic of calcium, like any other element, begins with the indication of its location in the periodic table. After all, it provides an opportunity to learn a lot about this atom:

• Charge of the nucleus;
• The number of electrons and protons, neutrons;
• Degree of oxidation, higher and lower;
• Electronic configuration and other important things.

The element considered by us is located in the fourth large period to the second group, the main subgroup and has the ordinal number 20. Also Mendeleyev's chemical table shows the atomic weight of calcium - 40.08, which is the average value of the existing isotopes of the given atom.

The degree of oxidation is one, always constant, equal to +2. The formula of higher oxide CaO. The Latin name of the element is calcium, hence the symbol of the atom Ca.

Characterization of calcium as a simple substance

Under normal conditions, this element is metal, silvery white. The formula of calcium as a simple substance is Ca. Due to its high chemical activity, it is capable of forming a variety of compounds belonging to different classes.

In the solid aggregate state, the human body is not part of the body, therefore it represents a value for industrial and technical needs (mainly chemical syntheses).

It is one of the most common metals in the earth's crust, about 1.5%. Refers to the group of alkaline earths, as it dissolves in water gives alkalis, but in nature it occurs in the form of multiple minerals and salts. A lot of calcium (400 mg / l) is included in the composition of sea water.

Crystal cell

The characteristic of calcium is explained by the structure of the crystal lattice, which can be of two types (since there is an alpha and beta form):

• Cubic face-centric;
• Body-centered.

The type of bond in a molecule is metallic, at lattice sites, like for all metals, atom-ions.

Being in nature

There are several basic substances in nature that contain this element.

1. Sea water.
2. Rocks and minerals.
3. Living organisms (shells and shells, bone tissue and so on).
4. Underground waters in the earth's crust.

You can identify the following types of rocks and minerals, which are natural sources of calcium.

1. Dolomite is a mixture of calcium carbonate and magnesium carbonate.
2. Fluorite is calcium fluoride.
3. Gypsum is CaSO ₄ · 2H ₂ O.
4. Calcite is chalk, limestone, marble is calcium carbonate.
5. Alabaster - CaSO ₄ · 0.5H ₂ O.
6. Apatity.

A total of about 350 different minerals and rocks that contain calcium.

Methods of obtaining

In a free form, it was not possible to separate the metal for a long time, since its chemical activity is high, you can not find it in pure form in nature. Therefore, until the XIX century (1808), the element in question was another enigma, which was borne by Mendeleyev's table.

Calcium as a metal was able to synthesize the English chemist Humphry Davy. It was he who first discovered the features of the interaction of melts of solid minerals and salts with electric current. To date, till now the most actual way of obtaining this metal is the electrolysis of its salts, such as:

• A mixture of calcium and potassium chlorides;
• A mixture of fluoride and calcium chloride.

It is also possible to extract calcium from its oxide by using the aluminothermy method widely used in metallurgy.

Physical properties

Characterization of calcium by physical parameters can be described by several points.

1. The aggregate state is solid under normal conditions.
2. The melting point is 842 ^° C.
3. The metal is soft, can be cut with a knife.
4. Color - silvery white, shiny.
5. It has good conductor and thermal conductivity properties.
6. With prolonged heating it passes into a liquid, then a vaporous state, losing its metallic properties. The boiling point is 1484 ^° C.

The physical properties of calcium have one feature. When there is pressure on the metal, then at some point in time it loses its metallic properties and the ability to conduct electrical conductivity. However, with a further increase in the effect, it is again restored and manifests itself as a superconductor, several times higher in terms of these parameters than other elements.

Chemical properties

The activity of this metal is very high. Therefore, there are many interactions in which calcium enters. Reactions with all non-metals for him - a common thing, because as a reductant, he is very strong.

1. Under normal conditions, it reacts easily with the formation of the corresponding binary compounds with: halogens, oxygen.
2. When heated: hydrogen, nitrogen, carbon, silicon, phosphorus, boron, sulfur and others.
3. In the open air immediately interacts with carbon dioxide and oxygen, so it becomes covered with a gray coating.
4. It reacts violently with acids, sometimes with inflammation.

Interesting properties of calcium are manifested when it comes to it in the composition of salts. So, beautiful cave stalactites and stalagmites growing on the ceiling and walls are nothing else than calcium carbonate formed over time from water, carbon dioxide and bicarbonate under the influence of processes inside the underground waters.

Considering how much metal is active in the ordinary state, store it in laboratories, as well as alkaline. In a dark glass dish, with a tightly closed lid and under a layer of kerosene or paraffin.

A qualitative reaction to the calcium ion is the coloration of the flame in a beautiful, rich brick-red color. Also, the metal in the compounds can be identified by the insoluble precipitates of some of its salts (calcium carbonate, fluoride, sulfate, phosphate, silicate, sulfite).

Metal compounds

Varieties of metal compounds are as follows:

• oxide;
• Hydroxide;
• Calcium salts (medium, acidic, basic, double, complex).

Calcium oxide is known as quicklime. CaO is used to create building material (lime). If the oxide is doused with water, then the corresponding hydroxide will be obtained, exhibiting the properties of alkali.

It is of great practical importance that different calcium salts are used, which are used in different branches of the economy. What kind of salt exists, we already mentioned above. We give examples of the types of these compounds.

1. The average salts are CaCO ₃ carbonate, Ca ₃ (PO ₄ ) ₂ phosphate and others.
2. Acid - hydrogen sulfate CaHSO ₄ .
3. The main ones are bicarbonate (NaOH) ₃ PO ₄ .
4. Complex - [Ca (NH ₃ ) ₈ ] Cl _2.
5. Double - 5Ca (NO ₃ ) ₂ * NH ₄ NO ₃ * 10H ₂ O.

It is in the form of compounds of this class that calcium is important for biological systems, since salts are the source of ions for the body.

Biological role

What is calcium important for the human body? There are several reasons.

1. It is the ions of this element that are part of the intercellular substance and tissue fluid, participating in the regulation of excitation mechanisms, the production of hormones and neurotransmitters.
2. Calcium accumulates in the bones, enamel in the amount of about 2.5% of the total body weight. This is quite a lot and plays an important role in strengthening these structures, preserving their strength and sustainability. Growth of an organism without this is impossible.
3. Blood clotting also depends on the ions in question.
4. It is part of the heart muscle, participating in its stimulation and contraction.
5. He is a participant in the processes of exocytosis and other intracellular changes.

If the amount of calcium consumed is not enough, then the development of such diseases as:

• rickets;
• osteoporosis;
• Blood diseases.

The daily norm for an adult is 1000 mg, and for children from 9 years, 1,300 mg. In order to prevent an overabundance of this element in the body, it should not exceed the indicated dose. Otherwise, bowel disease may develop.

For all other living beings, calcium is no less important. For example, many invertebrate animals, although they do not have a skeleton, but external means of strengthening them are also formations of this metal. Among them:

• Mollusks;
• Mussels and oysters;
• Sponges;
• Coral polyps.

All of them wear on their back or in principle form in the process of vital activity a certain external skeleton, which protects them from external influences and predators. The main constituent of it is calcium salts.

Vertebrate animals, like humans, need the ions in question for normal growth and development and receive them with food.

Calcium containing preparations

There are many options by which it is possible to fill the missing norm of an element in the body. Best of all, of course, natural methods are products containing the desired atom. However, if this is for some reason insufficient or impossible, the medical path is also acceptable.

So, the list of products containing calcium, approximately this:

• Dairy and sour-milk products;
• a fish;
• greenery;
• Cereals (buckwheat, rice, baking from whole-grain flour);
• Some citrus fruits (oranges, tangerines);
• Beans;
• All nuts (especially almonds and walnuts).

If on any products the allergy or it is impossible to use them for other reason to restore a level of the necessary element in an organism the calcium containing preparations will help.

They are all salts of this metal, which have the ability to be easily absorbed by the body, quickly absorbed into the blood and intestines. Among them the most popular and used are the following.

1. Calcium chloride is a solution for injection or for ingestion in adults and children. It differs in the concentration of salt in the composition, it is used for "hot jabs", since it causes exactly this feeling when injected. There are forms with fruit juice to facilitate ingestion.
2. Calcium gluconate. Produced as tablets (0.25 or 0.5 g), and solutions for intravenous injection. Often in the form of tablets contains various fruit supplements.
3. Calcium lactate - available in tablets of 0.5 g.