Phosphorus

We explain what phosphorus is, and its main characteristics. In addition, you will understand what it is for and where this chemical element is found.

What is phosphorus?

Phosphorus is a chemical element of the Periodic Table that is represented with the symbol P. It has atomic number 15 and atomic mass 30.97 amu. It is a very reactive non-metal. which is found in the earth's crust mainly as part of inorganic phosphates (PO₄^3-), which are ions that form salts. It is also found as part of living beings.

In addition, phosphorus forms several allotropes, and each has different properties and uses in various industries. Besides, Special attention must be paid to phosphorus levels in the planet's waters because when it is found at excessive levels, it can cause uncontrolled growth of some aquatic species that affect the rest of the species that live in the waters.

Phosphorus allotropes

This chemical element forms several allotropes. Allotropes are the different ways in which the atoms of a chemical element can bond. The allotropes of phosphorus are white phosphorus, red phosphorus and black phosphorus.

• He white phosphorus It is very toxic and flammable.
• He red phosphorus It is more stable and less toxic, it is the phosphorus that is used to make matches.
• He black phosphorus It is not flammable and conducts electricity.

Some examples of the structures of phosphorus allotropes are:

Phosphorus properties

Phosphorus is present in organic and inorganic chemical compounds. On the other hand, phosphorus has different physical and chemical properties that vary depending on the allotrope it is forming. In this sense, the main physical and chemical properties of phosphorus are:

Chemical properties of phosphorus

When it forms white phosphorus:

• It is the most reactive.
• It spontaneously oxidizes with oxygen in the air, emitting light, which is known as “phosphorescence.”
• It undergoes an exothermic reaction (reaction that releases heat) when in contact with heat and light, and is transformed into red phosphorus.

When it forms red phosphorus:

• Reacts violently with oxidants to form phosphorus pentoxide (P₂EITHER₅). This reaction also produces white smoke.

Physical properties of phosphorus

Property	white phosphorus	red match	black phosphorus
Appearance	Waxy, translucent, white to yellowish	Amorphous, reddish	Similar to graphite, black
electrical conductivity	Does not conduct electricity	Does not conduct electricity	Conduct electricity
Density	It is the densest	It has intermediate density	It is the least dense
Toxicity	Toxic	less toxic	Non-toxic
Notable phenomena	Glows in the dark (phosphorescence)	Used in safety matches	Presents thermal and electrical conductivity

Biological function of phosphorus

Phosphorus is considered an essential chemical element because it is part of chemical compounds that are essential for the vital functions of living organisms. For example:

• Inorganic phosphates (PO₄^3-) are part of DNA and RNA molecules.
• The adenosine triphosphate (ATP) molecule is responsible for transporting and storing energy in the cell.
• Phosphorus is involved in tissue growth, repair and conservation processes.
• Phosphorus is part of bones and teeth.
• Phosphorus is involved in the proper functioning of the kidneys, muscle contraction and nerve signals.

What is phosphorus for?

Phosphorus is used in various processes carried out by humans. It has been used in industrial processes, in laboratories and in medicine. Some applications of phosphorus are:

• It is used in the synthesis of various chemical compounds such as phosphorus trichloride (PCl₃) and phosphorus pentachloride (PCl₅).
• It is used to make matches that have been used worldwide to generate fire.
• Specifically, white phosphorus has been used to manufacture munitions and generate smoke in military activities.
• It is used to produce fertilizers.
• It is used in the food industry to produce additives.
• It is used as a component of cleaning products.

Where is phosphorus found?

The match It is found in nature as part of different minerals such as apatite (Ca₅(P.O.₄)₃(F,Cl,OH)), which is mainly found in Russia, Morocco and the United States. Thus, phosphorus is fundamentally present as part of sedimentary rocks, which when they suffer wear due to adverse weather conditions, release phosphorus into the soil and water. Marine sediments and soils are important reserves of phosphorus.

On the other hand, phosphorus is part of living beings, as it is present in DNA and RNA molecules. In addition, seeds, legumes and vegetables also contain phosphorus.

Effects of phosphorus on the environment

Excess phosphorus in rivers and lakes produces a process called “eutrophication.” Eutrophication is the excessive growth of algae and aquatic microorganisms due to the consumption of high levels of nutrients, such as phosphorus.

These algae and microorganisms excessively consume the oxygen dissolved in the water, which causes the death of aquatic living beings and also reduces drinking water reserves.

Thus, phosphorus reaches rivers and lakes as a result of runoff when excess fertilizers, pesticides and detergents are dumped. In this sense, on many occasions Phosphorus has gone from being a necessary nutrient to becoming a pollutant

On the other hand, white phosphorus is very poisonous and flammable and, when it comes into contact with the skin, it causes burns. Furthermore, when a human being suffers prolonged exposure to white phosphorus, they suffer from phosphonecrosis, which consists of necrosis of the jaw.

Phosphorus cycle

The phosphorus cycle is the circulation of phosphorus on planet Earth. Through this process, phosphorus moves between different ecosystems and the environment that surrounds them. It's a pretty slow cycle Because phosphorus does not form volatile chemical compounds, it cannot enter the atmosphere.

The phosphorus cycle is made up of different stages:

1. Weathering It consists of the decomposition of rocks due to the impact of wind, rain, temperature and other erosive agents. In the case of rocks containing phosphorus, weathering causes phosphorus to be released into the soil and into the waters of seas, rivers and lakes.

2. Absorption by plants Phosphorus present in the soil in the form of phosphates (PO₄^3-) is absorbed by plants through their roots.

3. Absorption by animals Phosphorus can be incorporated by herbivorous animals when they consume plants and by carnivores when they eat herbivorous animals.

4. Decomposition and mineralization The phosphorus contained in plants and animals is released into the soil when these living things die.

5. Sedimentation and rock formation Phosphorus found at the bottom of lakes, rivers and seas is compressed to form phosphate rocks.

6. Subduction The phosphorus present in the sunken plates can return to the Earth's surface during the eruption of volcanoes.

References

• Fernández, MT (2007). Phosphorus: friend or enemy. ICIDCA. On Sugar Cane Derivatives, 41(2), 51-57.
• Cerón Rincón, LE, & Ancízar Aristizábal Gutiérrez, F. (2012). Dynamics of the nitrogen and phosphorus cycle in soils. Colombian Journal of Biotechnology, 14(1), 285-295.
• Múnera Vélez, GA (2014). Phosphorus, an essential element for plant life. Technological University of Pereira. Book.
• Francis A. Carey, Robert M. Giuliano. (2014) Chemistry Organic.McGRAW-HILL/INTERAMERICANA EDITORES, SA DE CV