| Bill's World of Nitrogen | |||||||||||||||||
| History of Nitrogen | Nitrogen | ||||||||||||||||
|
Nitrogen was recognized as an individual substance by Daniel Rutherford of the University of Edinburgh in 1772, who noted that a small animal in a closed space removed one of the comonents of the air, and that a gas remained that was incapable of supproting life. The presence of nitrogen in the air was also recognized by Karl Wilhelm Scheele in connection with his work on oxygen. It remained, howerer, for Antoine Laurent Lavoisier to identify nitrogen as an element. It was he who gave it the name, azote, meaning "without life." The English word, nitrogen, is derived from a Greek term meaning "niter producing" because of its presence in potassium nitrate. Researches by Henry Cavendish, described in 1784, indicated that about 0.8% of an inactive gas remained after nitrogen and oxygen had been combined by repeated passage of an electric spark through air, the products of reaction being removed by an alkaline solution. It was also observed a century later by Lord Rayleigh that nitrogen from different sources had different densities. This led to the discovery by Sir William Ramsay in 1894 that what had been considered to be nitrogen in past years was a mixture made up mainly of nitrogen, but which contained other inert gases, most of which was argon, which constitutes about 0.94% of the earth's atmosphere. Nitrogen is a chemical element that forms compounds that are essential to life. Free nitrogen is a gas at ordinary temperatures and pressures, with no taste, odor, or color. It is the most abundant element in the atmosphere, accounting for about 78 percent of the volume and 75 percent of the weight in the atmosphere. Nitrogen does not combine readily with other elements. It dissolves in water. |
Name: Nitrogen Symbol: N Atomic Number: 7 Atomic Weight: 14.0067 Specific gravity: 0.81 (liquid form) Melting point: -346 F (-210 C)(63.14K) Boiling point: -320.4 F (-195.8 C)(77.35K) Orbital electronic configuration: (He)2s22p3 First ionization energy: (eV) 14.534 Second ionization energy: (eV) 29.593 Third ionization energy: (eV) 47.426 Electronegativity: 3.04 Atomic volume: 17.3 cm3/mol Atomic Radius: (A) 0.75 Bonding Radius: (A) 0.75 Oxidation states: + or - 3,5,4,2 Density: (g/ml) 1.251 Heat of vaporization (kJ/mol) 2.7928 Heat of fusion (kJ/mol) 0.3604 Specific heat capacity: (Jg-1k-1) 1.04 Crystal structure: hexagonal 1st ionization energy 1402.3 kJ/mol electronegativity 3.04 2nd ionization energy 2856 kJ/mol electron affinity -6.75 kJ/mol 3rd ionization energy 478 kJ/mol Specific heat 1.04 J/gK Heat Atomization 473 kJ/mol atoms | ||||||||||||||||
| Nitrogen. Whats it all about? | |||||||||||||||||
|
Nitrogen is a colorless gas which occurs free in the earth's atmosphere and is the principal component of air (78.09% by volume as compared to 20.95% for oxygen.) All living things require nitrogen to live and grow. Nitrogen is an essential element in amino acids, the "building blocks" of proteins. Most living things, including animals and plants, cannot use free nitrogen. They can use only nitrogen that is combined with other elements. Certain bacterias and algae combine free nitrogen from the atmosphere with other elements, forming nitrogen compounds that can be absorbed by food-making organisms such as algae and plants. The nitrogen compounds produced by these organisms that do not make food, including protozoans and animals. Ther process of forming nitrogen compunds from atmospheric nitrogen is called nitrogen fixation. When an organism dies and decays, some of the nitrogen it contains is returned to the atmosphere. Through the years a number of laboratory methods were developed for the preparation of nitrogen from its compounds. Ammonium nitrite decomposes into nitrogen and water. Nitrogen from the air may be combined with actice metals and the reulting nitrides may then be decomposed, producing pure nitrogen. Ammonia, when passed over heated copper oxyide, breaks up into nitrogen and hydrogen, the latter combining with oxygen to form water. A mixture of gases containing mainly nitrogen, with a small amount of argon and traces of the other zero-valence gases, is made by passing air through heated coke and absorbing the carbon dioxide in water. A very pure grade of nitrogen is made by liquefying air and fractionating the liquid with a column and heat exchangers and activated charcoal adsorber. Oxygen is removed at the bottom of the column along with a part of the nitrogen. Oxygen boils at -183 degrees C. and nitrogen at -196 degrees C. For Most Purposes it is not necessary to remove argon and smaller amounts of the other inert gases from nitrogen, but for special purposes, adsorption techniques can by employed to take out every component but nitrogen in the liquid air process. The main use of nitrogen is in the prodcution of ammonia, in which nitrogen and hydrogen are made to combine under high pressure in the presence of catalysts. A smaller amount is used in making calcium cyanamide by passing nitrogen over calcium carbide in electric resistance furnace. Nitrogen is also used for inert atmosphere in various processes. Liquid engineering, particularly in certain types of lasers, masers, and powerful magnets. The nitrogen cycle (look below for pic.) is the series of chemical actions by which free atmoshperhic nitrogen is converted into soluble compounds, in organic growth, and returned to the atmoshpere through organic decomposition. Some free nitrogen from the air is introduced into the soil during thunderstorms, when it is fixed in the form of oxides by electrical discharges and is conveyed to the land as nitric or nitrous acid by means of rain. The most important natural method, however, is the fixation of nitrogen by means of bacteria on the roots of certain leguminous plants (clover, alfalfa, beans, peas); these bacteria convert atmospheric nitrogen to nitrates which fertilize the soil. The soil nitrates are converted by plants into proteins, which, when eaten by animals, are turned into animal proteins. With the decay of plant and animal matter, nitrogen is released to the atmosphere, thus completing the cycle. The Nitrogen cycle is the series of natural processes by which certain nitrogen-containing substances from air and soil are made useful to living things, are used by them, and are returned to the air and soil. All living things must have nitrogen to build proteins. Because of the chemical nature of nitrogen gas, however, they cannot obtain that element directly from the air. Instead, food-making organisms such as plants obtain it from the soil by absorbing nitrates (various nitrogen compounds containing oxygen) and ammonium compounds (various nitrogen compounds containing hydrogen). The nitrogen cycle is essential to plants in unfertilized soils because in such soils the nitrogen compunds are not available to the plants in any other way. Animals, and other living things that do not make their food, depend on the nitrogen cycle indirectly. Most animals, for example, eat plants or eat plant-eating animals. Thus, through the nitrogen cycle, food-making organisms obtain the necessary nitrogen through nitrogen fixation and (to a greater extent) through nitrification. At the same time, nitrogen compounds are returned to the soil through decay and nitrogen is returned to the air through denitrification. In soils in which many plants are raised and few are left to decay (as in farm soils), the nitrogen cycle does not supply enough nitrogen to support plant growth. In these soils natural or artificial fertilizers, containing nitrates or ammonium compounds, are needed. | |||||||||||||||||
| |||||||||||||||||
| |||||||||||||||||
|
This page has been visited
|