Can you describe allotropic modifications of phosphorus? Our article is devoted to the properties of this particular substance. In nature, there are several allotropic modifications of phosphorus. Let's get acquainted with this topic in more detail.
The concept of allotropy
Chemical elements can form different types of simple substances. This phenomenon is called allotropy. It can be due to two reasons. In the first case, this is a different number of atoms of an element in a substance. For example, oxygen and ozone. They are made up of oxygen. Only the first gas contains two atoms, and the second - three.
Phosphorus allotropy has a different nature. When combined, its atoms are able to form crystal lattices of various types. How is this possible? Three covalent bonds are formed in the molecule of this substance. But in pairs they are connected only by one. The remaining two units of valency are used to attach the third and fourth atoms. Thus, either an atomic or molecular crystal lattice is formed.
Phosphorus in nature
Under normal conditions, this substance does not occur in its pure form. This is due to its high chemical activity. The main phosphorus compounds are salts - phosphorites and apatites. Phosphorus atoms are part of cell membranes, bone tissue and nucleic acids, which are carriers of hereditary information.
Properties and name of allotropic modifications of phosphorus
Depending on the type of crystal lattice, this substance can be represented by several modifications. It is white, yellow, red and black. Allotropic modifications of phosphorus got their names due to color. Under high pressure conditions, white and red phosphorus turns to black. The physical properties of each species have sharp differences. Let's look at each of them separately.
White phosphorus
Obtaining this allotropic modification of phosphorus can be called a "fantastic coincidence." At the end of the XVII century, the German alchemist Henning Brand worked on obtaining a philosopher's stone. According to the legends of that time, he possessed amazing properties: turn ferrous metals into gold, give eternal life and freedom. By evaporating urine, the scientist received a dry residue. Since this substance glowed in the dark, Brand decided that this was the philosopher's stone. In fact? it was white phosphorus.
Consider the properties and structure of this allotropic modification of phosphorus. This crystalline substance is colorless or yellowish. Its hardness is small - under water, white phosphorus can be cut with a knife. It is insoluble in water, melts at a temperature of 44 degrees Celsius.
This allotropic modification of phosphorus differs from all others in significant chemical activity. Already at 40 degrees, it reacts with oxygen and ignites. This form is the most poisonous.
Yellow phosphorus
This substance belongs to the group of highly toxic. Yellow phosphorus is called crude white. It is highly flammable in air. In this case, a bright green flame is formed and a large amount of white caustic smoke is released. Since yellow phosphorus is capable of self-ignition, it is stored and transported only under a layer of water.
Red phosphorus
Allotropic modifications of phosphorus can turn into each other. This requires certain conditions. So, with prolonged heating under high pressure and in the presence of carbon dioxide, white phosphorus turns into red. For the first time this reaction was carried out at the end of the 19th century by the Austrian chemist Ritter Schretter.
Red phosphorus is chemically less active. This substance is soluble only in molten lead and bismuth. The process of ignition does not occur when the temperature rises. Red phosphorus turns into steam, which then turns into white. But for a fire to occur, it is necessary to hit or grind this substance.
This modification is less toxic than white. Therefore, it is widely used in the production of matches as the basis for the substance of the box surface.
Black phosphorus
Only in the 20th century did it become known that phosphorus forms allotropic modifications, which are its most stable and least active form. This is black phosphorus. This time, the discovery belonged to the American physicist Percy Bridgman, who was a Nobel Prize laureate. But he received a high award not for receiving black phosphorus, but for creating a device capable of creating high atmospheric pressure. This was one of the conditions under which red phosphorus turns into black.
Visually, this modification resembles graphite. These are black crystals with a metallic sheen, greasy to the touch, insoluble in water and organic substances. This substance melts only at a temperature of 1000 degrees.
Areas of use
By comparing the properties and structure of allotropic modifications of phosphorus, it becomes clear a large number of areas of use of this substance. Let's consider some of them. Yellow phosphorus, which forms a thick smokescreen, makes this substance a raw material for the defense and military industries. In particular, it is used in the manufacture of tracer bullets. The phosphorus track, which is formed when it is shot, stretches for a whole kilometer. The ability of phosphorus to shine is used in the manufacture of paints.
Many phosphorus compounds are widely used. In combination with gray, the red modification is used to obtain matches. Chloride is used as a plasticizer and an additive for pest control.
The chemical element phosphorus is necessary for all living organisms for normal development. His daily norm is about 1.5 grams. Replenishment of these stocks is possible due to the consumption of cereals, legumes and dairy products.
So, phosphorus is a chemical element that can be in the form of several simple substances. In other words, to form allotropic modifications. Depending on the type of crystal lattice, it can be white, yellow, red or black phosphorus. Each of these modifications has physical and chemical properties that are different from others, and a physiological effect on the body and its field of application.