Characteristics of potassium. The structure of potassium. Potassium compounds

This article will give a description of potassium in terms of physics and chemistry. The first of these sciences studies the mechanical and external properties of substances. And the second - their interaction with each other - this is chemistry. Potassium - the nineteenth in the account element in the periodic table. It belongs to alkali metals. This article will also consider the electronic formula of potassium, and its behavior with other substances, etc. This is one of the most active metals. Science, which deals with the study of this and other elements - chemistry. Grade 8 provides for the study of inorganic substances and their properties. Therefore, this article will be useful for schoolchildren. So, let's begin.

Characterization of potassium in terms of physics

This is a simple substance, which under normal conditions is in a solid aggregate state. The melting point is sixty-three degrees Celsius. The same metal boils up when the temperature reaches seven hundred and sixty-one degrees Celsius. The substance under consideration has a silvery-white color. Has a metallic luster. The density of potassium is eighty six hundredths of a gram per centimeter cubic. This is a very light metal. The formula of potassium is very simple - it does not form molecules. This substance consists of atoms that are located close to each other and have a crystal lattice. The atomic mass of potassium is equal to thirty-nine grams per mole. Its hardness is very low - it can easily be cut with a knife, like cheese.

Potassium and Chemistry

To begin with, potassium is a chemical element that has very high chemical activity. Even to store it in the open air it is impossible, as it instantly begins to react with surrounding substances. Potassium is a chemical element that belongs to the first group and the fourth period of the periodic table. It has all the properties that are characteristic of metals.

Interaction with simple substances

These include: oxygen, nitrogen, sulfur, phosphorus, halogens (iodine, fluorine, chlorine, bromine). In order, let us consider the interaction of potassium with each of them. Interaction with oxygen is called oxidation. During this chemical reaction, potassium and oxygen are consumed in a molar ratio of four parts to one, resulting in the formation of the oxide of the metal in question in two parts. This interaction can be expressed by the following reaction equation: 4K + O2 = 2K2O. When burning potassium, you can observe a bright violet flame. Therefore, this reaction is considered qualitative for the determination of potassium. Reactions with halogens are called according to the names of these chemical elements: iodination, fluorination, chlorination, bromination. These interactions can be called addition reactions, since the atoms of two different substances combine into one. An example of such a process is the reaction between potassium and chlorine, as a result of which chloride of the metal is formed. To carry out this interaction, it is necessary to take these two components - two moths of the first and one of the second. As a result, two moles of a potassium compound are formed. This reaction is expressed by the following equation: 2K + CI2 = 2KSI. With nitrogen, potassium can give compounds when burning in the open air. During this reaction, the metal and nitrogen in question are consumed in a molar ratio of six parts to one, resulting in the formation of potassium nitride in two parts. This can be shown in the form of the following equation: 6K + N2 = 2K3N. This compound is a green-black crystal. With phosphorus, the metal under consideration reacts by the same principle. If we take three moles of potassium and one mole of phosphorus, we get one mole of phosphide. This chemical interaction can be written in the form of such a reaction equation: 3K + P = K3P. In addition, potassium is able to react with hydrogen, forming a hydride. As an example, the following equation can be given: 2K + H2 = 2KN. All reaction reactions take place only in the presence of high temperatures.

Interaction with complex substances

Characterization of potassium from the point of view of chemistry provides for consideration of this topic. Complex substances with which potassium reacts are water, acids, salts, oxides. With all of them, the metal in question reacts differently.

Potassium and water

This chemical element reacts violently with it. This produces hydroxide, as well as hydrogen. If we take two moles of potassium and water, we get the same amount of potassium hydroxide and one mole of hydrogen. This chemical interaction can be expressed by the following equation: 2K + 2H2O = 2KOH = H2.

Reactions with acids

Since potassium is an active metal, it easily displaces the hydrogen atoms from their compounds. An example is the reaction that occurs between the substance under consideration and hydrochloric acid. To conduct it, you need to take two moles of potassium, and also the acid in the same amount. As a result, potassium chloride is formed - two moles and hydrogen - one mole. This process can be written down by the following equation: 2K + 2HCI = 2KSI + H2.

Potassium and oxides

With this group of inorganic substances, the metal under consideration reacts only with considerable heating. If the metal atom, which is part of the oxide, is passive than the one we are talking about in this article, there is, in fact, an exchange reaction. For example, if we take two moles of potassium and one mole of cuprum oxide, as a result of their interaction, one mole of the oxide of the chemical element in question and a pure kuprum can be obtained. This can be shown in the form of the following equation: 2K + CuO = K2O + Cu. This is where the strong reducing properties of potassium appear.

Interaction with bases

Potassium is able to react with metal hydroxides, which are to the right of it in the electrochemical activity series. In this case, its reducing properties also appear. For example, if we take two moles of potassium and one mole of barium hydroxide, as a result of the substitution reaction, we get substances such as potassium hydroxide in the amount of two moles and pure barium (one mole) - it will precipitate. The chemical interaction can be represented as the following equation: 2K + Ba (OH) 2 = 2KOH + Ba.

Reactions with salts

In this case, potassium still shows its properties as a strong reducing agent. Replacing atoms of chemically more passive elements, it allows to obtain pure metal. For example, if three moles of potassium is added to aluminum chloride in an amount of two moles, then as a result of this reaction we get three moles of potassium chloride and two moles of aluminum. Express this process with the help of the equation can be as follows: 3K + 2AІСІ3 = 3КСІ2 + 2АІ.

Reactions with fats

If potassium is added to some organic substance of this group, it will also displace one of the hydrogen atoms. For example, when stearin is mixed with the metal in question, potassium stearate and hydrogen are formed. The obtained substance is used to make liquid soap. On this, the characteristics of potassium and its interactions with other substances terminate.

Use of potassium and its compounds

Like all metals, considered in this article is necessary for many processes in the industry. The main use of potassium occurs in the chemical industry. Due to its high chemical activity, pronounced alkali metal and reducing properties, it is used as a reagent for many interactions and obtaining a variety of substances. In addition, alloys with a potassium content are used as coolants in nuclear reactors. Also, the metal considered in this article finds its application in electrical engineering. In addition to all of the above, it is one of the main components of fertilizers for plants. In addition, its compounds are used in a wide variety of industries. Thus, in the extraction of gold, potassium cyanide is used, which serves as a reagent for the recovery of valuable metals from ores. In the production of glass, potassium carbonate is used. Phosphates of the chemical element in question are components of various cleaning agents and powders. In matches there is chlorate of this metal. In the manufacture of films for old cameras, the bromide of the element in question was used. As you already know, it can be obtained by brominating potassium in a high temperature condition. In medicine, the chloride of this chemical element is used. In soap making - stearate and other derivatives of fats.

Preparation of the metal under consideration

Nowadays, potassium is extracted in laboratories in two main ways. The first is to restore it from hydroxide with sodium, which is chemically even more active than potassium. And the second is getting it from chloride, also with the help of sodium. If you add the same amount of sodium to one mole of potassium hydroxide, one mole of alkali sodium and pure potassium is formed. The equation for this reaction is as follows: KOH + Na = NaOH + K. For the second type of reaction, the chloride of the metal and sodium must be mixed in equal molar proportions. As a result, substances such as potassium salt and potassium are formed in the same ratio. To express this chemical interaction it is possible with the help of such a reaction equation: KSI + Na = NaCl + K.

The structure of potassium

The atom of this chemical element, like all others, consists of a nucleus containing protons and neutrons, as well as electrons that rotate around it. The number of electrons is always equal to the number of protons that are inside the nucleus. If any electron disconnects or joins the atom, it ceases to be neutral and turns into an ion. They are of two kinds: cations and anions. The former have a positive charge, while the latter have a negative charge. If an electron has joined the atom, it turns into an anion, but if any of the electrons left their orbit, the neutral atom becomes a cation. Since the serial number of potassium, according to Mendeleyev's table, is nineteen, there are as many protons in the nucleus of this chemical element as well. Therefore, we can conclude that there are nineteen electrons around the nucleus. The number of protons that are contained in the structure of an atom can be determined by subtracting the atomic number of the chemical element from the atomic mass. So we can conclude that there are twenty protons in the potassium core. Since the metal considered in this article belongs to the fourth period, it has four orbits, on which the electrons are located evenly, which are constantly in motion. The scheme of potassium is as follows: in the first orbit there are two electrons, on the second - eight; As well as on the third, on the last, fourth, orbit, only one electron rotates. This explains the high level of chemical activity of a given metal - its last orbit is not completely filled, so it seeks to connect with some other atoms, as a result of which their electrons of the last orbits become common.

Where can you find this element in nature?

Since it has extremely high chemical activity, it is not found anywhere on the planet in its pure form. It can be seen only in the composition of various compounds. The mass fraction of potassium in the earth's crust is 2.4 percent. The most common minerals, which include potassium, are salvinite and carnallite. The first has the following chemical formula: NaCl • KCl. It has a motley coloring and consists of many crystals of various colors. Depending on the ratio of potassium chloride to sodium, as well as the presence of impurities, it can contain red, blue, pink, orange components. The second mineral, carnallite, looks like transparent, soft blue, light pink or pale yellow crystals. Its chemical formula looks like this: KCl • MgCl2 • 6H2O. It is crystalline hydrate.

The role of potassium in the body, the symptoms of lack and excess

It, together with sodium, maintains the water-salt balance of the cell. He also participates in the transfer between the membranes of the nerve impulse. In addition, it regulates the acid-base balance in the cell and throughout the body as a whole. It takes part in the processes of metabolism, counteracts the appearance of edema, is part of the cytoplasm - about fifty percent of it - the salt of the metal in question. The main signs that the body lacks potassium is puffiness, the appearance of a disease such as dropsy, irritability and disturbances in the work of the nervous system, retardation of reaction and memory impairment. In addition, an inadequate amount of this trace element adversely affects the cardiovascular and muscular systems. A lack of potassium for a very long time can provoke a heart attack or stroke. But because of the excess of potassium in the body can develop a small intestine ulcer. To balance your diet in such a way that you get a normal amount of potassium, you need to know what products it contains.

Food with a high content of the micronutrient in question

First of all, these are nuts, such as cashews, walnuts, hazelnuts, peanuts, almonds. Also, a lot of it is in potatoes. In addition, potassium is found in dried fruits, such as raisins, dried apricots, prunes. This element is rich in pine nuts. Also its high concentration is observed in beans: beans, peas, lentils. Sea kale is also rich in this chemical element. Still other products containing this element in large quantities are green tea and cocoa. In addition, in high concentration it is found in many fruits, such as avocados, bananas, peaches, oranges, grapefruits, apples. Many cereals are rich in the micronutrient in question. First of all, it is pearl barley, as well as wheat and buckwheat groats. In parsley and Brussels sprouts, too, there is a lot of potassium. In addition, it is found in carrots and melons. Onions and garlic have a considerable amount of the chemical element in question. Chicken eggs, milk and cheese are also high in potassium. The daily norm of this chemical element for the average person is from three to five grams.

Conclusion

After reading this article, we can conclude that potassium is an extremely important chemical element. It is necessary for synthesizing many compounds in the chemical industry. In addition, it is used in many other industries. Also, it is very important for the human body, therefore, it must regularly and in the necessary quantity go there with food.