Phosphorus (P)
Phosphorus (P) is a chemical element with the atomic number 15 and an atomic mass of approximately 30.97. Found in the nitrogen group of the periodic table, phosphorus exhibits a melting point of 44.1 degrees Celsius and a boiling point of 280 degrees Celsius, with a density of 1.82 grams per cubic centimeter. This element is highly reactive and is never found in its free state in nature; instead, it occurs primarily in phosphate minerals, which are vital for various biological processes. Phosphorus is essential for life, as it forms a crucial part of DNA and adenosine triphosphate (ATP), the energy currency of cells.
Historically, phosphorus has had significant applications, from its initial discovery in the 17th century to its use in fertilizers, detergents, and military applications today. It exists in several allotropes, including white, red, and black phosphorus, each with distinct properties and uses. Deposits of phosphorus are mainly found in regions like the Middle East, Russia, and parts of the United States. Given its vital role in agriculture and biology, phosphorus remains a critical element for sustaining life and supporting food production worldwide.
Subject Terms
Phosphorus (P)
Phosphorus (P) is an element in the nitrogen group of the periodic table of elements. It has an atomic number of 15 and an atomic mass of 30.9738 atomic mass units (u). It melts at 44.1 degrees Celsius (111.4 degrees Fahrenheit) and boils at 280 degrees Celsius (536 degrees Fahrenheit). Its density at 20 degrees Celsius (68 degrees Fahrenheit) is 1.82 grams per centimeter squared. Its oxidation states are −3, +3, and +5. Its electron configuration is 1s22s22p63s23p3.
Phosphorus has many nicknames, including “the devil’s element,” due to both its being the thirteenth element discovered and its luminescence when exposed to oxygen. Because of its reactive nature, phosphorus is never found as a free element in nature; it is always bound to another element.
Typically phosphorus occurs in the form of phosphate minerals, so called because they contain the phosphate anion (PO43−). Phosphate is also found in human urine, bat guano, and bone ash.
Phosphorus is a key component of phosphoric acid and has many commercial, military, and industrial uses, such as in fertilizers, explosives, and detergents. It is also necessary for the health of both animals and plants.
Phosphorus occurs in various forms, or allotropes, including white, yellow, red, violet, and black. Deposits are primarily found in the Middle East, Russia, China, and several places within the United States.
Background
From its discovery in 1669 to the modern age, phosphorus has had a robust history and influence on science, particularly biology and chemistry. After its discovery, the element became a key ingredient in matches. It was not until a century after its discovery that phosphorus was found to exist in nature in the form of bone ash and animal excrement.
Phosphorus was first discovered in 1669 by German alchemist Hennig Brand (ca. 1630–ca. 1710), who was attempting to create the philosopher’s stone. The philosopher’s stone is a fabled alchemical tool that was believed to be able to turn one metal or element into another, such as lead to gold. Brand’s plan was to turn human urine into the philosopher’s stone through evaporation. His attempts to create the legendary object failed, but he discovered a new element.
In 1680, Irish chemist and physicist Robert Boyle (1627–91) became the first person to use phosphorus to make matches. He worked with his assistant Ambrose Godfrey (1660–1741) and German chemist Johann Becher (1635–82). Nearly a century later, in 1769, phosphorus was found to be a component element of phosphate. In addition to being formed from bone ash, phosphate is a naturally occurring material.
In 1951, James Watson (b. 1928) and Francis Crick (1916–2004), using research performed by Rosalind Franklin (1920–58), developed a mathematical model of deoxyribonucleic acid (DNA). It was discovered a year later that the skeletal structure of DNA was composed of phosphates. In other words, life cannot exist without phosphorus and its derivatives. The physical structure of DNA, and of its counterpart ribonucleic acid (RNA), is based on the chemical properties exhibited by phosphorus.
Uses of Phosphorus
There are many uses of phosphorus and its derivatives in commercial, industrial, and military applications. Commercially, phosphorus and phosphates are used in detergents and matches; industrially, phosphoric acid is used to make fertilizer. In the military, phosphorus and phosphates are used in incendiary devices, tracers, smoke screens, and Molotov cocktails. In addition, all living organisms need phosphorus in order to live and grow.
Phosphorus is used commercially as phosphoric acid and as phosphates. It is primarily used in soaps and detergents, toothpastes, and household cleaners. The presence of phosphates and phosphoric acid contributes to the abrasive qualities of the cleaners. Phosphates bind to dirt, allowing it to be washed away more easily, while their abrasiveness helps remove plaque and buildup from the surface of teeth. Phosphates also help soften hard water by binding to metal ions such as magnesium, calcium, and iron in the water, thus removing minerals that could otherwise damage plumbing, industrial, or other equipment.
Phosphorus-based compounds are used in the production of fertilizers, which are used worldwide for growing a wide variety of crops. Phosphorus accounts for only about 0.11 percent of the earth by mass, and it is not evenly distributed. As plants require phosphorus for photosynthesis and growth, its presence in fertilizers helps ensure healthy, strong plants to support the bottom layer of the food chain.
Phosphorus is used all over the world in the production of incendiary devices, tracers, and smoke screens. An incendiary device is a weapon that is designed to start a fire through a chemical reaction, not detonation. They are most commonly used militarily for destroying equipment. A tracer is a bullet that has been either coated in or filled with a pyrotechnic material such as phosphorus or magnesium. When the bullet is fired, the material is ignited and burns brightly, allowing the trajectory of the bullet to be visible from hundreds of meters away. Smoke screens typically use the white form of phosphorus, which spontaneously ignites upon contact with the atmosphere to produce a thick cloud of white smoke. However, due to the tendency of white-phosphorus smoke to rise too quickly, many militaries have begun using red phosphorus instead, which only spontaneously ignites at 260 degrees Celsius (500 degrees Fahrenheit) or above.
Phosphorus and its derivatives are essential to the existence of life as we know it. Living organisms obtain cellular energy via adenosine triphosphate (ATP), which plants synthesize during photosynthesis and animals synthesize from the fats, proteins, and carbohydrates obtained from food. In addition, phosphates are the backbone of DNA, bonding with deoxyribose and nitrogenous bases to form the chain of nucleotides that make up a DNA molecule.
Harms of Phosphorus
Runoff containing phosphorus has been shown to promote dangerous algal blooms. Toxins released by blue-green algae (cyanobacteria) can kill off plant and animal life in freshwater bodies. Consequently, some governments have regulated the use of phosphorus-containing products, and manufacturers have begun to eliminate or reduce phosphates from their cleaning agents and chemical fertilizers.
Exposure to white phosphorus can severely harm or kill humans, burning down to the bone. It can damage airways and eyes, cause multiorgan failure and shock, and/or permanently contract muscles and other tissues. Although not banned under international law, white phosphorus weapons are controversial, and their use in civilian areas may violate the Convention on Certain Conventional Weapons (CCW).
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