Among all the elements of the periodic system are several of these, without which not only develop various diseases in living organisms, but in general it is impossible to live a normal life and grow.One such - calcium.
interesting that when it comes to this metal as a simple substance, that no use for a man he has not even harm.But you need only mention the Ca2 + ions as directed there is a lot of points that characterize their importance.
position of calcium in the periodic
characteristic of calcium, as well as any other element begins with the provisions of its place in the periodic system.After all, it gives the opportunity to learn a lot about this atom:
- nuclear charge;
- number of electrons and protons, neutrons;
- degree of oxidation, the highest and lowest;
- electron configuration and other important things.
before us is an element in the fourth period, a large second group, the main group and has a serial number 20. Also, the chemical periodic table shows the atomic weight of calcium - 40.08, which is the average value of existing isotopes of a given atom.
degree of oxidation alone, is always constant, equal to two.The formula of highest oxide CaO.The Latin name of the element calcium, hence a symbol of the atom Ca.
characteristic of calcium as a simple substance
Under normal conditions, the element is a metal silver-white color.The formula of calcium as a simple substance - calcium.Due to the high chemical activity and is capable of forming a plurality of compounds belonging to various classes.
in the solid state of the human body is not included, so the value is for industrial and technical purposes (mainly chemical synthesis).
is one of the most widespread on the share of the earth's crust metal, about 1.5%.It refers to the group of alkaline earth, as by dissolution in water gives an alkali, but is found in nature in the form of multiple minerals and salts.A lot of calcium (400 mg / l) is included in the composition of sea water.
Crystalline
Feature calcium is due to the structure of the crystal lattice, which he can be of two types (as there is an alpha and beta form):
- cubic granetsentricheskaya;
- obemnotsentricheskaya.
type bond in the molecule - metal lattice sites, as all - metal atom ions.
Being in nature
There are several basic substances in nature which contain this element.
- Seawater.
- Rocks and Minerals.
- Living organisms (shells of, bones and so on).
- Groundwater in the earth's crust.
can indicate the following types of rocks and minerals, which are natural sources of calcium.
- Dolomite - a mixture of calcium carbonate and magnesium.
- Fluorite - calcium fluoride.
- gypsum - CaSO4 · 2H2O.
- Calcite - chalk, limestone, marble - calcium carbonate.
- Alabaster - CaSO4 · 0.5H2O.
- Apatity.
Total emit about 350 different minerals and rocks, which contain calcium.
Methods for producing
in free form select the metal for a long time it was not possible, since its chemical activity is high in nature in its pure form can not be found.Therefore, until the XIX century (1808) was the element of another mystery, which was carrying the periodic table.
calcium as the metal was able to synthesize the English chemist Humphry Davy.It was he who first discovered the features of the interaction of melts solid minerals and salt with an electric shock.Today, still the most relevant way to obtain this metal is the electrolysis of its salts, such as:
- mixture of calcium chloride and potassium;
- mixture of fluoride and calcium chloride.
can also remove calcium from its oxide using a common method in the industry aluminothermy.
physical properties
characteristic of calcium on physical parameters can be described by a few points.
- Physical state - under normal circumstances the firm.
- Melting point - 842 0C.
- metal soft, can be cut with a knife.
- Color - silvery white, shiny.
- has good conduction and heat-conducting properties.
- Prolonged heating becomes a liquid, and then the vapor state, losing the properties of the metal.The boiling point of 1484 0C.
physical properties of calcium have one feature.When pressure is exerted on the metal, it will at some time loses its metallic properties and the ability to conductivity.However, with further increase in the impact of the newly restored and behaves like a superconductor, several times the indicators according to the other elements.
chemical properties
activity of the metal is very high.So there are a lot of interactions in which calcium enters.The reactions of all non-metals for him - the usual case, because as a reducing agent, he is very strong.
- Under normal conditions is readily reacted to form the corresponding binary compounds: halogen, oxygen.When heated
- hydrogen, nitrogen, carbon, silicon, phosphorus, boron, sulfur, and others.
- Outdoors immediately reacts with carbon dioxide and oxygen, so covered with gray bloom.
- acid reacts violently, sometimes with inflammation.
interesting properties of calcium appear when it comes to him in the composition of salts.So beautiful cave stalactites and stalagmites, which grow on the ceiling and walls, it is nothing like calcium carbonate, formed over time from water, carbon dioxide and hydrogen under the influence of processes within groundwater.
Given how active metal in the normal state, it is stored in the laboratory, as well as alkaline.The dark glass container with a tight lid and a layer of kerosene or paraffin.
Qualitative reaction to calcium ion - is the color of a flame in a beautiful, full of brick-red color.Also identified metal compounds can be composed on an insoluble precipitation of some of its salts (calcium carbonate, fluoride, sulfate, phosphate, silicate, sulfite).
metal compounds
Varieties of metal compounds as follows:
- oxide;
- hydroxide;
- calcium salts (average, acidic, basic, double, complex).
Calcium oxide is known as quicklime.CaO is used to create the building material (lime).If you put out the oxide with water, you get the corresponding hydroxide, exhibiting properties of alkali.
great practical importance is different calcium salts which are used in different sectors of the economy.Which there are salt, we have already mentioned above.Here are some examples of the types of these compounds.
- Average salt - carbonate, CaCO3, phosphate, Ca3 (PO4) 2, and others.
- Sour - sulfate CaHSO4.
- Main - hydrogen (CaOH) 3PO4.
- Complex - [Ca (NH3) 8] Cl2.
- double - 5Ca (NO3) 2 * NH4NO3 * 10H2O.
It is in the form of compounds of this class of calcium is important for biological systems as a source of ions to the body are the salt.
biological role
What is the importance of calcium for the human body?There are several reasons.
- It ions of the element included in the intercellular substance, and tissue fluid, participating in the regulation of excitation mechanisms, the production of hormones and neurotransmitters.
- Calcium accumulates in bone, tooth enamel in an amount of about 2.5% of total body weight.This is quite a lot and plays an important role in strengthening of these structures, retaining their strength and stability.The growth of the organism is impossible without it.
- Blood clotting is also dependent on the considered ions.
- is a part of the heart muscle by participating in its excitation and contraction.
- is a member of the processes of exocytosis and other intracellular changes.
If the amount of calcium intake is not sufficient, it is possible the development of diseases such as:
- rickets;
- osteoporosis;
- blood diseases.
daily rate for an adult - 1,000 mg, and for children from 9 years of 1300 mg.In order to avoid a surplus in the body of this element should not exceed the indicated dose.Otherwise bowel disease may develop.
For all other living things calcium is not less important.For example, many invertebrates, though do not have a skeleton, but external means to strengthen their formations are also of metal.Among them:
- shellfish;
- mussels and oysters;
- sponges;
- coral polyps.
All they wear on their backs or in principle formed during the life of a exoskeleton, which protects them from external influences and predators.The main component of it - calcium salt.
Vertebrates as a person in need in these ions for normal growth and development and get their food.
Calcium containing drugs
There are many options with the help of which it is possible to make up the missing element in the normal body.Ideally, of course, natural methods - products containing the desired atom.However, if for any reason insufficient or impossible, clinical pathway is also acceptable.
For a list of foods containing calcium, about this:
- milk and milk products;
- fish;
- greens;
- crops (buckwheat, rice, baked whole wheat);
- certain citrus fruits (oranges, tangerines);
- legumes;
- all nuts (especially almonds and walnuts).
If for some food allergies or can not use them for any other reason, the fill level of the desired item in the body will help the calcium-containing products.
They are the salt of the metal having the ability to easily digested quickly being absorbed into the blood and intestines.Among them, the most popular and useful are the following.
- Calcium chloride - solution for injection or oral administration to adults and children.Different concentration of salt in the composition used for "hot shots" since it causes a feeling when vkalyvaniem.Any form of fruit juice to facilitate ingestion.
- calcium gluconate.Available as tablets (0.25 or 0.5 g), and solutions for intravenous injection.Often in the form of pills includes various fruit flavors.
- Calcium Lactate - available in tablets of 0.5 g
