In the main subgroup of the fifth group, along with nitrogen, there is also phosphorus. Can metal be considered non-metal or this element? Compared with nitrogen, it has a lower electronegativity, but still applies to active non-metals. In our article we will consider the most important physical and chemical properties of phosphorus, as well as determine the scope of its application in industry.
The position of the element in the periodic system
Phosphorus refers to p-elements, its atom has three energy levels. The last of them has five electrons, three of which are unpaired. In an excited state, the P atom contains five free electrons. This fact explains the appearance of phosphorus compounds in which it is not trivalent, but has a valency equal to five, for example, P 2 O 5 - phosphorus pentoxide. Non-metal, due to its high activity, is absent in nature in the free state and is found only in the form of compounds. The natural element has the only stable isotope with a relative atomic mass of 31. Phosphorus is part of many rocks and minerals, its content in the earth's crust is 0.08%.
Allotropic modifications
The different arrangement of atoms in the crystal lattices of a substance leads to the appearance of some modifications. For example, black phosphorus is very similar to graphite. It is also greasy to the touch and exhibits semiconductor properties. In industry, the material is obtained from white phosphorus, heating the latter to 200 ° C and subjecting it to a pressure of 12,000 atm.
Red phosphorus is a powdery, non-toxic substance. In its detailed study, it was found that the compound is a mixture of phosphorus modifications, which differ in some ways, for example, in color.
Another allotropic modification is white phosphorus. Is it metal or non-metal? This substance exhibits typical non-metallic properties, in addition, it is very toxic. Get it by concentrating phosphorus vapor. Unlike the red species, it can dissolve in carbon disulfide. If white phosphorus is subjected to weak heating for a long time, it goes into the modification of red phosphorus.
Chemical characterization
In its compounds with other elements, P can exhibit the following oxidation states: +3, +5, -3. In a vaporous state at a temperature below 800 °, as well as in the liquid phase, the substance molecule has the formula P 4 .
Various modifications of the substance have dissimilar chemical characteristics. How to answer the question, what is phosphorus metal or not? It is necessary to turn to the structure of its atom, which in the excited state has five valence electrons. The most active non-metal in terms of chemistry is white phosphorus, which is easily oxidized even at ordinary temperature, during which it begins to glow, and can also ignite spontaneously. For these reasons, it is recommended to store it covered with water. In its properties, red phosphorus is a less active substance than its white modification.
Binary connections
Like metal or non-metal, phosphorus can react with oxygen:
4P + 3O 2 → 2P 2 O 3
The product of the reaction is phosphine gas, a very toxic substance used as a chemical weapon. It is easy to recognize by the specific smell of garlic. Phosphorus hydride is able to attach hydrogen halides, for example, such as hydrogen iodide, forming a compound - phosphonium iodide PH 4 I. Interaction with metals leads to the appearance of phosphides:
2P + 3Ca = Ca 3 P 2 .
Like metal, phosphorus also reacts with non-metals, for example, sulfur, carbon, chlorine:
2P + 3Cl 2 = 2PCl 3
Phosphides easily react with water, decomposing to phosphine:
Mg 3 P 2 + 6H 2 O = 3Mg (OH) 2 + 2PH 3 (phosphine)
Oxides
Among the binary compounds of the element with oxygen, the most important are its oxides: P 2 O 5 and P 2 O 3 . Phosphorus trioxide, otherwise called phosphoric anhydride, is a crystalline compound whose melting point is 22.5 °. Under ordinary conditions, it has the appearance of a wax-like mass. In the laboratory, it is obtained by burning phosphorus in an atmosphere poor in oxygen. Although this oxide exhibits the properties of a strong reducing agent, it is used extremely rarely due to its high toxicity. What properties, metal or non-metal, does phosphorus oxide manifest in its reactions? It can react with water to form phosphoric acid and phosphine. The substance interacts with hydrogen chloride, resulting in phosphate acid and phosphorus chloride.
Another compound, phosphorus pentoxide, has the characteristics of a typical acid oxide. It can be obtained by burning a portion of phosphorus in the atmosphere with an excess of oxygen. Under normal conditions, the compound reacts very actively with water and forms metaphosphoric, and when heated, orthophosphoric acid. In addition, phosphorus pentoxide takes away moisture, so it can be used as a desiccant for liquid substances and gases.
Phosphoric acid
The most famous phosphoric acids are metaphosphoric, orthophosphoric and pyrophosphoric, whose formula is H 4 P 2 O 7 . The last of them is formed by heating H 3 PO 4 . Orthophosphoric acid, the salts of which are used as raw materials for the production of mineral fertilizers, is of the greatest practical importance. It is a white solid, very soluble in water. Being an acid of medium strength, it does not have pronounced oxidizing properties. Like an electrolyte, it dissociates stepwise, therefore it forms two rows of salts: medium - phosphates, acid - hydrophosphates and dihydrogen phosphates. In industry, phosphate acid is obtained by thermal and extraction methods. Since acids correspond to phosphorus oxides, the answer to the question of whether phosphorus is a metal or non-metal is unequivocal: it is an active non-metallic element.
Spread in nature
The most important mineral containing a high concentration of phosphorus is apatite. It has many varieties, the most common of which is fluorapatite. Another type of mineral consisting of phosphorus compounds is sedimentary rock phosphorite.
The element is included in the group of ten most important chemical elements for living organisms. Its greatest content was found in the form of phospholipids - organic compounds that are part of cell membranes, hormones and other biologically active substances. A high element content (about 0.38%) is recorded in the nervous tissue that forms the central and peripheral parts of the nervous system of humans and other vertebrates. In addition, phosphorus compounds enter muscle and bone tissue. The latter contains calcium phosphate - a salt that gives dentin and bone bones strength and high hardness. In the metabolism of plant organisms, along with magnesium and iron, phosphorus plays an important role as a regulator of the processes of formation and ripening of fruits and seeds. That is why, along with nitrogen and potassium, phosphorus is considered the main nutrient of plants.
In our article, we examined the properties of phosphorus and answered the question: what is phosphorus - metal or non-metal? This is a typical non-metallic element with high chemical activity.