MUHAMMAD RIZWAN

ROLL NO# 7343

GEOLOGY (B)

UNIVERSITY OF HARIPUR

THE NITROGEN FAMILYThe nitrogen family consists of the five elements that make

up Group 15 of the periodic table: nitrogen, phosphorus, arsenic, antimony, and bismuth. These five elements share

one important structural property: they all have five electrons in the outermost energy level of their atoms.

Nonetheless, they are strikingly different from each other in both physical properties and chemical behavior.

Nitrogen is a nonmetallic gas; phosphorus is a solid nonmetal; arsenic and antimony are metalloids; and

bismuth is a typical metal.

NITROGEN

Nitrogen is a colorless, odorless, tasteless gas with a melting point of −210°C (−346°F) and a boiling point of −196°C (−320°F). It is the most abundant element in the atmosphere, making up about 78 percent by volume of the air that surrounds Earth. The element is much less common in Earth's crust, however, where it ranks thirty-third (along with gallium) in abundance. Scientists estimate that the average concentration of nitrogen in crustal rocks is about 19 parts per million, less than that of elements such as neodymium, lanthanum, yttrium, and scandium, but greater than that of well-known metals such as lithium, uranium, tungsten, silver, mercury, and platinum.

The most important naturally occurring compounds of nitrogen are potassium nitrate (saltpeter), found primarily in India, and sodium nitrate (Chile saltpeter), found primarily in the desert regions of Chile and other parts of South America. Nitrogen is also an essential component of the proteins found in all living organisms.

Credit for the discovery of nitrogen in 1772 is usually given to Scottish physician Daniel Rutherford (1749–1819). Three other scientists, Henry Cavendish, Joseph Priestley, and Carl Scheele, could also claim to have discovered the element at about the same time. Nitrogen was first identified as the product left behind when a substance is burned in a closed sample of air (which removed the oxygen component of air).

USESThe industrial uses of nitrogen have increased dramatically in the past few decades. It now ranks as the second most widely produced chemical

in the United States with an annual production of about 57 billion pounds (26 billion kilograms).

The element's most important applications depend on its chemical inertness (inactivity). It is widely used as a blanketing atmosphere in metallurgical processes where the presence of oxygen would be harmful. In the processing of iron and steel, for example, a blanket of nitrogen placed above the metals prevents their reacting with oxygen, which would form undesirable oxides in the final products

PHOSPHORUSPhosphorus exists in three allotropic forms (physically or chemically different forms of the same substance): white, red, and black. The white form of phosphorus is a highly active, waxy solid that catches fire spontaneously when exposed to air. In contrast, red phosphorus is a reddish powder that is relatively inert (inactive). It does not catch fire unless exposed to an open flame. The melting point of phosphorus is 44°C (111°F), and its boiling point is 280°C (536°F). It is the eleventh most abundant element in Earth's crust

Phosphorus always occurs in the form of a phosphate, a compound consisting of phosphorus, oxygen, and at least one more element. By far the most abundant source of phosphorus on Earth is a family of minerals known as the appetites. Apatite contain phosphorus, oxygen, calcium, and a halogen (chlorine, fluorine, bromine, or iodine). The state of Florida is the world's largest producer of phosphorus and is responsible for about a third of all the element produced in the world

Phosphorus also occurs in all living organisms, most abundantly in bones, teeth, horn, and similar materials. It is found in all cells, however, in the form of compounds essential to the survival of all life. Like carbon and nitrogen, phosphorus is cycled through the environment. But since it has no common gaseous compounds, the phosphorus cycle occurs entirely within the solid and liquid (water) portions of Earth's crust

USES

Uses. About 95 percent of all the phosphorus used in industry goes to the production of phosphorus compounds. By far the most important of these is phosphoric acid, which accounts for about 83 percent of all phosphorus use in industry. A minor use is in the manufacture of safety matches

PHOSPHORIC ACIDPhosphoric acid. Phosphoric acid (H 3 PO 4 ) typically ranks about number seven among the chemicals most widely produced in the United States. It is converted to a variety of forms, all of which are then used in the manufacture of synthetic fertilizer, accounting for about 85 percent of all the acid produced. Other applications of phosphoric acid include the production of soaps and detergents, water treatment, the cleaning and rustproofing of metals, the manufacture of gasoline additives, and the production of animal feeds

ARSENIC &ANTIMONY

Arsenic and antimony are both metalloids. That is, they behave at times like metals and at times like nonmetals. Arsenic is a silver-gray brittle metal that tarnishes when exposed to air. It exists in two allotropic forms: black and yellow. Its melting point is 817°C (1502°F) at 28 atmospheres of pressure, and its boiling point is 613°C (1135°F), at which temperature it sublimes (passes directly from the solid to the vapor state

Antimony also occurs in two allotropic forms: black and yellow. It is a silver-white solid with a melting point of 630°C (1170°F) and a boiling point of 1635°C (2980°F). Both arsenic and antimony were identified before the birth of modern chemistry—at least as early as the fifteenth century.

Arsenic is a relatively uncommon element in Earth's crust, ranking number 51 in order of abundance. It is actually produced commercially from the flue dust obtained from copper and lead smelters (metals separated by melting) since it generally occurs in combination with these two elements.

Antimony is much less common in Earth's crust than is arsenic, ranking number 62 among the elements. It occurs most often as the mineral stibnite (antimony sulfide), from which it is obtained in a reaction with iron metal

USES

Arsenic is widely employed in the production of alloys (a mixture of two or more metals or a metal and a nonmetal) used in shot, batteries, cable covering, boiler tubes, and special kinds of solder (a melted metallic alloy used to join together other metallic surfaces). In a very pure form, it is an essential component of many electronic devices. Traditionally, compounds of arsenic have been used to kill rats and other pests, although it has largely been replaced for that purpose by other products.

Antimony is also a popular alloying element. Its alloys can be found in ball bearings, batteries, ammunition, solder, type metal, sheet pipe, and other applications. Its application in type metal reflects an especially interesting property: unlike most materials, antimony expands as it cools and solidifies from a liquid. Because of that fact, type metal poured into dies in the shape of letters expands as it cools to fill all parts of the die. Letters formed in this process have clear, sharp edges

BISMUTHBismuth is a typical silvery metal with an interesting reddish tinge to it. It has a melting point of 271°C (520°F) and a boiling point of 1560°C (2840°F). It is one of the rarest elements in Earth's crust, ranking 69 out of 75 elements for which estimates have been made. It occurs most commonly as the mineral bismite (bismuth oxide), bismuthinite (bismuth sulfide) and bismutite (bismuth oxycarbonate). Like arsenic and antimony, bismuth was identified as early as the fifteenth century by the pre-chemists known as the alchemists.

USES

Nearly all of the bismuth produced commercially is used for one of two applications: in the production of alloys or other metallic products and in pharmaceuticals. Some of its most interesting alloys are those that melt at low temperatures and that can be used, for example, in automatic sprinkler systems. Compounds of bismuth are used to treat upset stomach, eczema (a skin disorder), and ulcers, and in the manufacture of face powders

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