Chemistry

In chemistry

Chemistry

Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

, the term inert is used to describe a substance that is not chemically reactive

Chemical reaction

A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...

.

The noble gas

Noble gas

The noble gases are a group of chemical elements with very similar properties: under standard conditions, they are all odorless, colorless, monatomic gases, with very low chemical reactivity...

es were previously known as inert gases because of their perceived lack of participation in any chemical reactions. The reason for this is that their outmost electron shell

Electron shell

An electron shell may be thought of as an orbit followed by electrons around an atom's nucleus. The closest shell to the nucleus is called the "1 shell" , followed by the "2 shell" , then the "3 shell" , and so on further and further from the nucleus. The shell letters K,L,M,.....

s (valence shells) are completely filled, so that they have little tendency to acquire or lose electrons. It is now known that these gases in fact do react to form chemical compound

Chemical compound

A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

s, such as xenon tetrafluoride

Xenon tetrafluoride

Xenon tetrafluoride is a chemical compound with chemical formula . It was the first discovered binary compound of a noble gas. It is produced by the chemical reaction of xenon with fluorine, , according to the chemical equation:...

. Hence, they have been renamed to noble gases. However, a large amount of energy is required to drive such reactions, usually in the form of heat, pressure, or radiation, often assisted by catalysts. The resulting compounds often need to be kept in moisture-free conditions at low temperatures to prevent rapid decomposition back into their elements.

The term inert may also be applied in a relative sense. For example, molecular nitrogen

Nitrogen

Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

 is inert under ordinary conditions, existing as diatomic

Diatomic

Diatomic molecules are molecules composed only of two atoms, of either the same or different chemical elements. The prefix di- means two in Greek. Common diatomic molecules are hydrogen , nitrogen , oxygen , and carbon monoxide . Seven elements exist in the diatomic state in the liquid and solid...

 molecules, . The presence of a strong triple covalent bond

Covalent bond

A covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding....

 in the molecule renders it unreactive under normal circumstances. Nevertheless, nitrogen gas does react with the alkali metal

Alkali metal

The alkali metals are a series of chemical elements in the periodic table. In the modern IUPAC nomenclature, the alkali metals comprise the group 1 elements, along with hydrogen. The alkali metals are lithium , sodium , potassium , rubidium , caesium , and francium...

 lithium to form compound lithium nitride

Lithium nitride

Lithium nitride is a compound of lithium and nitrogen with the formula Li3N. It is the only stable alkali metal nitride...

 (Li₃N), even under ordinary conditions. Under high pressures and temperatures and with the right catalysts, nitrogen becomes more reactive; the Haber process

Haber process

The Haber process, also called the Haber–Bosch process, is the nitrogen fixation reaction of nitrogen gas and hydrogen gas, over an enriched iron or ruthenium catalyst, which is used to industrially produce ammonia....

 uses such conditions to produce ammonia

Ammonia

Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

 from atmospheric nitrogen.

Inert atmospheres consisting of gases such as argon

Argon

Argon is a chemical element represented by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table . Argon is the third most common gas in the Earth's atmosphere, at 0.93%, making it more common than carbon dioxide...

, nitrogen

Nitrogen

Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

, or helium

Helium

Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...

 are commonly used in chemical reaction chambers and in storage containers for air-sensitive

Air sensitive

Air sensitivity is a term used, in particular in chemistry, to denote the reactivity of chemical compounds with some constituent of air. Most often, reactions occur with atmospheric oxygen or water vapor , although reactions with the other constituents of air such as carbon monoxide , carbon...

 or water-sensitive substances, to prevent unwanted side-reactions of these substances with air and water.

Pesticides

The Federal Insecticide, Fungicide, and Rodenticide Act

Federal Insecticide, Fungicide, and Rodenticide Act

The Federal Insecticide, Fungicide, and Rodenticide Act , et seq. is a United States federal law that set up the basic U.S. system of pesticide regulation to protect applicators, consumers, and the environment. It is administered by the Environmental Protection Agency and the appropriate...

 divides the ingredients in pesticides into two groups: active and inert. An inert chemical, under this context, is one that does not have a toxic effect on the species the pesticide is meant to combat, but that does not rule out that it may still have a biological activity on other species, including being toxic to humans. Solvents, propellents, preservatives, among others, are thus considered inert ingredients in pesticides.

Since 1997, the United States Environmental Protection Agency

United States Environmental Protection Agency

The U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...

 has recommended that pesticide manufacturers label the non-active ingredients as "other ingredients" rather than "inert" to prevent misinformation to the public.

Number theory

In the branch of mathematics known as algebraic number theory

Algebraic number theory

Algebraic number theory is a major branch of number theory which studies algebraic structures related to algebraic integers. This is generally accomplished by considering a ring of algebraic integers O in an algebraic number field K/Q, and studying their algebraic properties such as factorization,...

, a prime ideal

Prime ideal

In algebra , a prime ideal is a subset of a ring which shares many important properties of a prime number in the ring of integers...

 is said to be inert if it is still prime

Prime ideal

In algebra , a prime ideal is a subset of a ring which shares many important properties of a prime number in the ring of integers...

 when considered in an extension field. Such a prime might have instead split

Splitting of prime ideals in Galois extensions

In mathematics, the interplay between the Galois group G of a Galois extension L of a number field K, and the way the prime ideals P of the ring of integers OK factorise as products of prime ideals of OL, provides one of the richest parts of algebraic number theory...

 as a product of other prime ideals, but by being inert it remains essentially unchanged.

Munitions

In the field of weapon

Weapon

A weapon, arm, or armament is a tool or instrument used with the aim of causing damage or harm to living beings or artificial structures or systems...

s and explosives, an inert munition is one in which all energetic material such as primer

Percussion cap

The percussion cap, introduced around 1830, was the crucial invention that enabled muzzleloading firearms to fire reliably in any weather.Before this development, firearms used flintlock ignition systems which produced flint-on-steel sparks to ignite a pan of priming powder and thereby fire the...

s, fuses

Fuse (explosives)

In an explosive, pyrotechnic device or military munition, a fuse is the part of the device that initiates function. In common usage, the word fuse is used indiscriminately...

, and the explosive or incendiary

Incendiary device

Incendiary weapons, incendiary devices or incendiary bombs are bombs designed to start fires or destroy sensitive equipment using materials such as napalm, thermite, chlorine trifluoride, or white phosphorus....

 material

Material

Material is anything made of matter, constituted of one or more substances. Wood, cement, hydrogen, air and water are all examples of materials. Sometimes the term "material" is used more narrowly to refer to substances or components with certain physical properties that are used as inputs to...

s within them have been removed or otherwise rendered harmless. Inert munitions are used in military and naval training, and they are also collected and displayed by public museums, or by private parties. See also military dummy. Typically, American and NATO inert munitions are painted entirely in light blue and/or have the word "INERT" stenciled on them in prominent locations.