Which nitrogen containing substance is generally unreactive

The main source of helium is from natural gas, where it is separated out from the other components by fractional distillation. Helium liquefies at 4. Some materials become superconductors when immersed in liquid helium; in these materials, there is no resistance to the flow of electricity. Superconducting magnets are used for an important medical imaging technology called Magnetic Resonance Imaging MRI , which allows images of tissues and organs to be obtained.

A related technology is used by chemists to obtain information that can be used to deduce the structures of molecules; this technique is called Nuclear Magnetic Resonance NMR ; the two technologies are basically the same, but the term "nuclear" is avoided in the medical application because of its unpleasant associations even though there is no nuclear radiation involved.

Helium is also used in blimps, where the combination of being lighter than air and nonflammable makes it much safer than hydrogen as demonstrated in the explosion of the Hindenburg. It is also used in deep-sea diving, since helium is less soluble in the bloodstream than nitrogen, and reduces the risk of the diver suffering nitrogen narcosis, high pressure nervous syndrome HPNS , or the bends. Breathing helium gas causes the voice to become higher pitched because helium is less dense than air, changing the frequency of the sound waves generated in the larynx.

Neon is a colorless, odorless, unreactive gas which liquefies at Neon was discovered in by Sir William Ramsay see entry on Argon below and his assistant Morris Travers while working with a sample of krypton. The name comes from the Greek word for "new," neos. It is found in the Earth's crust at a concentration of 70 ppt, making it the 80th most abundant element; it is found in the atmosphere at a concentration of 18 ppm by volume.

Neon which is used commercially is extracted from liquid air by fractional distillation. Neon is used primarily in neon lights ; stimulating neon with electricity causes it to emit an intense red light. Other noble gases are used in "neon lights" as well, to produce different colors. Neon is also used in some underwater breathing mixtures; liquid neon is used in low-temperature cooling. Argon is a colorless, odorless, unreactive gas which liquefies at It is found in the Earth's crust at a concentration of 1.

Argon which is used commercially is extracted from liquid air by fractional distillation. Argon had been observed before by Henry Cavendish in , but it had not been identified as an element. Because of its unreactivity, it was named for the Greek word for "idle," argos. When argon was discovered, it didn't fit with the reactivities of any other element on the periodic table, and chemists realized that there might be a whole family of previously-unrecognized elements, which we now recognize as Group 8A.

Argon is used in light bulbs because it is inert to the hot metal of the bulb filament; the filament would burn out much faster in air or even pure nitrogen. Nitrogen forms many compounds with oxygen. One of the most important of these is nitric oxide, NO, also known as nitrogen monoxide, which is produced in the body from the amino acid arginine; it acts as a vasodilator, causing blood vessels to relax and increasing blood flow.

Some heart medications, such as nitroglycerin and amyl nitrate, increase the amount of nitric oxide in the blood, allowing the delivery of more blood to the heart during an episode of heart pain angina or heart attack. The drug Viagra works by a similar mechanism, except that the blood is delivered elsewhere. Nitric oxide also acts as a neurotransmitter. In the atmosphere, nitric oxide is a pollutant, produced in automobile exhaust and power plants; it can be converted into nitrogen dioxide and nitric acid, HNO 3 , which leads to increased acidity levels in rain.

Nitrous oxide, N 2 O, also known as dinitrogen monoxide or laughing gas, is a mild anesthetic used in dentistry and surgery; it is also used as an aerosol propellant in cans of whipped cream. Nitrogen dioxide, NO 2 , is produced in the exhaust from motor vehicles, and reacts with hydrocarbons in the air to produce photochemical smog. Nitrogen is also found in a number of explosives.

Gunpowder contains potassium nitrate, KNO 3 , also known as saltpeter, which is a powerful oxidizing agent; the other components of gunpowder are sulfur, and coal. Nitroglycerin is made from the molecule glycerin or glycerol , which is a chain of three carbon atoms, each of which has an OH group on it; in nitroglycerine, the H on the OH is replaced by the nitro group, NO 2.

Nitroglycerin is dangerously unstable, but when mixed with kieselguhr diatomaceous earth , which acts as an adsorbent, it is safer to handle, and does not explode until set off by a smaller explosion from a detonator such as a blasting cap.

Dynamite was invented by the Swedish chemist Alfred Nobel in ; on his death, his fortune was used to establish the Nobel Prizes, which are awarded for outstanding achievements in the sciences, literature, and peace.

TNT 2,4,6-trinitrotoluene , is a benzene ring with a CH 3 group attached forming the toluene molecule to which three nitro groups are attached which is accomplished by the use of a mixture of concentrated nitric and sulfuric acids. TNT is stable for long periods of time, and is not shock sensitive as nitroglycerin is.

HMX, also known as octogen or cyclotetramethylene-tetranitramine, consists of a ring four carbon atoms and four nitrogen atoms, with each nitrogen atom having one nitro group bonded to it; this substance is used in plastic explosives, rocket propellants, and the detonator in nuclear warheads.

RDX, also known as cyclotrimethylenetrinitramine, cyclonite, hexogen, and T4, contains a ring of three carbon atoms and three nitrogen atoms, with each nitrogen bonded to a nitro group; it is used in mixtures with TNT, in plastic explosives, and in nuclear weapons. The ammonium nitrate and sulfate found in fertilizers can also produce powerful explosions under the "right" conditions: a ship in the harbor in Texas City which was carrying tons of ammonium nitrate exploded on April 15, , killing over people; the Alfred P.

Murrah Federal Building in Oklahoma City was destroyed by a bomb made from ammonium nitrate and nitromethane a motor fuel , killing people. Nitrogen gas is also what inflates the ubiquitous "air" bags that are used as safety devices in automobiles. An airbag canister contains about grams of sodium azide, NaN 3 ; when a collision is detected, a sensor sends an electric current through the sample, causing it to decompose into sodium metal which is converted into sodium salts by other reagents and nitrogen gas, which can inflate the cushioning bag in 15 to 25 milliseconds.

When mixed with hydrochloric acid, it forms a solution called aqua regia "royal water" , which is capable of dissolving even extremely unreactive metals such as gold and platinum. Deep-sea divers can suffer from a condition called "the bends" because of the increased amount of nitrogen dissolved in their blood at high pressure.

Increasing the pressure on a gas increases the solubility of a gas in a liquid Henry's Law ; one application of this is seen when a can of soda is opened — at high pressure in an unopened can, about 4 atmospheres of pressure , carbon dioxide is dissolved in the water in the soda, but when the can is opened, the pressure is released, and the dissolved gas comes bubbling out of the solution. Divers who have been underwater for a long time, especially at great depths, where the pressure is even higher, have increased amounts of nitrogen dissolved in their bloodstream; if they surface too quickly, the nitrogen can come bubbling out of the bloodstream, causing pain in the joints, dizziness, seizures, paralysis, or death.

Coming back to the surface slowly allows time for the nitrogen to come out of solution without forming bubbles; alternatively, a breathing mixture of oxygen and helium can be used, since helium is less soluble in the bloodstream than nitrogen. Phosphorus is a nonmetallic element that exists in several allotropic forms see below. It is found in the Earth's crust at a concentration of ppm, making it the 11th most abundant element. Phosphorus was the first element to have been discovered since ancient times, although compounds of phosphorus had been known for millennia.

It was first isolated by Hennig Brandt, an alchemist from Hamburg, in , from the residue obtained from concentrated, putrefied urine. The name comes from the Greek words phos "light" and phoros "bringing" , and refers to the fact that elemental phosphorus glows in the dark, and spontaneously bursts into flame in air.

Gaseous nitric oxide is the most thermally stable of the nitrogen oxides and is the simplest known thermally stable molecule with an unpaired electron. It is one of the air pollutants generated by internal combustion engines, resulting from the reaction of atmospheric nitrogen and oxygen during the combustion process.

At room temperature, nitric oxide is a colorless gas consisting of diatomic molecules. As is often the case with molecules that contain an unpaired electron, two molecules combine to form a dimer by pairing their unpaired electrons to form a bond.

Most substances with unpaired electrons exhibit color by absorbing visible light; however, NO is colorless because the absorption of light is not in the visible region of the spectrum. Dinitrogen trioxide exists only in the liquid and solid states. When heated, it reverts to a mixture of NO and NO 2. Commercially, it is possible to prepare nitrogen dioxide by oxidizing nitric oxide with air.

It is also responsible for the dimerization of NO 2. At low pressures or at high temperatures, nitrogen dioxide has a deep brown color that is due to the presence of the NO 2 molecule. At low temperatures, the color almost entirely disappears as dinitrogen tetraoxide, N 2 O 4 , forms.

At room temperature, an equilibrium exists:. It is unstable above room temperature, decomposing to N 2 O 4 and O 2. The nitrogen oxides exhibit extensive oxidation-reduction behavior.

Nitrous oxide resembles oxygen in its behavior when heated with combustible substances. N 2 O is a strong oxidizing agent that decomposes when heated to form nitrogen and oxygen. Because one-third of the gas liberated is oxygen, nitrous oxide supports combustion better than air one-fifth oxygen. A glowing splinter bursts into flame when thrust into a bottle of this gas.

Nitric oxide acts both as an oxidizing agent and as a reducing agent. For example:. Nitrogen dioxide or dinitrogen tetraoxide is a good oxidizing agent. Active metals such as the alkali metals and alkaline earth metals can reduce nitrogen to form metal nitrides.