Consider the chemical properties of alkaline earth metals. We define the features of their structure, production, location in nature, application.
The situation in the PS
To begin with, we determine the location of these elements in the periodic system of Mendeleev. They are located in the second group of the main subgroup. These include calcium, strontium, radium, barium, magnesium, beryllium. All of them at the external energy level contain two valence electrons. In general, beryllium, magnesium, and alkaline earth metals at the external level have ns2 electrons. In chemical compounds, they exhibit an oxidation state of +2. During interaction with other substances, they exhibit reducing properties, giving off electrons from an external energy level.
Change Properties
As the nucleus of an atom grows, beryllium, magnesium, and alkaline earth metals enhance their metallic properties, since an increase in the radius of their atoms is observed. Consider the physical properties of alkaline earth metals. In its normal state, beryllium is a gray metal with a steel luster. It has a dense hexagonal crystal lattice. Upon contact with atmospheric oxygen, beryllium immediately forms an oxide film, as a result of which its chemical activity decreases, a matte coating forms.
Physical properties
Magnesium as a simple substance is a white metal that forms an oxide coating in air. It has a hexagonal crystal lattice.
Physical properties of alkaline earth metals calcium, barium, strontium are similar. They are metals with a characteristic silver luster, covered under the influence of oxygen in the air with a yellowish film. In calcium and strontium, there is a cubic face-centered lattice; barium has a body-centered structure.
The chemistry of alkaline earth metals is based on the fact that they have a metallic character. That is why they are distinguished by high electrical and heat conductivity. Their melting and boiling points are higher than those of alkali metals.
Production methods
The production of beryllium in industrial volumes is carried out by reducing the metal from fluoride. The prerequisite for this chemical reaction is preheating.
Considering that alkaline earth metals in nature are in the form of compounds, electrolysis of their salt melts is carried out to produce magnesium, strontium, and calcium.
Chemical properties
The chemical properties of alkaline earth metals are associated with the need to first remove the oxide film layer from their surface. It determines the inertness of these metals to water. Calcium, barium, strontium, when dissolved in water, form hydroxides with pronounced basic properties.
The chemical properties of alkaline earth metals suggest their interaction with oxygen. For barium, the reaction product is peroxide; for all others, oxides are formed after the reaction. In all representatives of this class, oxides exhibit basic properties, only beryllium oxide is characterized by amphoteric properties.
The chemical properties of alkaline earth metals are also manifested in reactions with sulfur, halogens, and nitrogen. In reactions with acids, the dissolution of these elements is observed. Considering that beryllium belongs to amphoteric elements, it is able to enter into chemical interaction with alkali solutions.
Qualitative reactions
The basic formulas of alkaline earth metals, considered in the course of inorganic chemistry, are associated with salts. To identify representatives of this class in a mixture with other elements, you can use a qualitative definition. When salts of alkaline earth metals are added to the flame of an alcohol lamp, cation stains the flame. The strontium cation gives a dark red hue, the calcium cation gives an orange color, and the barium cation gives a green tone.
In order to identify barium cation, sulfate anions are used in a qualitative analysis. As a result of this reaction, white barium sulfate is formed, which is insoluble in inorganic acids.
Radium is a radioactive element that is naturally found in small amounts. When magnesium interacts with oxygen, a blinding flash is observed. This process was used for some time while photographing in dark rooms. Magnesium flashes are now replaced by electrical systems. The alkaline earth metal family includes beryllium, which reacts with many chemicals. Calcium and magnesium, like aluminum, can reduce such rare metals as titanium, tungsten, molybdenum, niobium. These methods of producing metals are called calcium thermal and magnesium thermal.
Application features
What is the use of alkaline earth metals? Calcium and magnesium are used to make light alloys and rare metals.
For example, magnesium is contained in duralumin, and calcium is a component of lead alloys used to make cable sheaths and create bearings. Widespread use of alkaline earth metals in technology in the form of oxides. Quicklime (calcium oxide) and burnt magnesium (magnesium oxide) are required for the construction industry.
When calcium oxide interacts with water, a significant amount of heat is released. Slaked lime (calcium hydroxide) is used for construction. A white suspension of this substance (milk of lime) is used in the sugar industry for the purification process of beet juice.
Metal salts of the second group
Salts of magnesium, beryllium, alkaline earth metals can be obtained by interaction with the acids of their oxides. Chlorides, fluorides, iodides of these elements are white crystalline substances, mainly highly soluble in water. Among sulfates, only magnesium and beryllium compounds have solubility. Its decrease from beryllium salts to barium sulfates is observed. Carbonates are practically insoluble in water or have minimal solubility.
Sulfides of alkaline earth elements in small quantities are contained in heavy metals. If you focus on them, you can get different colors. Sulfides are included in the composition of luminous compounds called phosphors. Apply similar paints to create luminous dials, road signs.
Common alkaline earth metal compounds
Calcium carbonate is the most abundant element on Earth. It is an integral part of such compounds as limestone, marble, chalk. Among them, the main application is limestone. This mineral is indispensable in construction, it is considered an excellent building stone. In addition, quicklime and slaked lime, glass, and cement are obtained from this inorganic compound.
The use of limestone gravel helps to strengthen roads, and thanks to the powder, the acidity of the soil can be reduced. Natural chalk is a shell of the oldest animals. This compound is used for the manufacture of rubber, paper, the creation of school crayons.
Marble is in demand among architects, sculptors. It was from marble that many of Michelangelo’s unique creations were created. Some of the Moscow metro stations are lined with marble tiles. Magnesium carbonate in large volumes is used in the manufacture of bricks, cement, glass. It is needed in the metallurgical industry to remove waste rock.
Calcium sulfate, naturally occurring in the form of gypsum (crystalline calcium sulfate hydrate), is used in the construction industry. In medicine, this compound is used to make casts, as well as to create plaster casts.
Alabaster (semi-aquatic gypsum), when interacting with water, produces a huge amount of heat. It is also applied in industry.
Epsom salt (magnesium sulfate) is used in medicine as a laxative. This substance has a bitter taste, it is found in sea water.
“Barite porridge” (barium sulfate) is not soluble in water. That is why this salt is used in x-ray diagnostics. Salt delays x-rays, which helps to detect diseases of the gastrointestinal tract.
In the composition of phosphorites (rocks) and apatites there is calcium phosphate. They are needed to produce calcium compounds: oxides, hydroxides.
Calcium plays a special role for living organisms. It is this metal that is needed to build the bone skeleton. Calcium ions are necessary to regulate the functioning of the heart, increase blood coagulation. Its lack causes disturbances in the functioning of the nervous system, loss of coagulability, and the loss of the ability of the hands to hold various objects normally.
In order to avoid health problems, every day a person should consume about 1.5 grams of calcium. The main problem is that in order for the body to absorb 0.06 grams of calcium, it is necessary to eat 1 gram of fat. The maximum amount of this metal is contained in lettuce, parsley, cottage cheese, cheese.
Conclusion
All representatives of the second group of the main subgroup of the periodic table are necessary for the life and work of modern man. For example, magnesium is a stimulant of metabolic processes in the body. It must be present in nerve tissue, blood, bones, and liver. Magnesium is an active participant in photosynthesis in plants, since it is an integral part of chlorophyll. Human bones make up about a fifth of the total weight. They contain calcium and magnesium. Oxides, salts of alkaline earth metals have found diverse applications in the construction industry, pharmaceuticals and medicine.