List of reagents in organic chemistry

Hii everyone I am going share some idea about how many reagents are present in organic chemistry based on current data which I have  so let see, first I am going to tell you what is reagents?
So Reagents are "substances or compounds that are added to a system in order to bring about a chemical reaction or are added to see if a reaction occurs.Some reagents are just a single element. However, most processes require reagents made of chemical compound Some of the most common ones.
Types of reagents ;

Acetic acid: an organic acid is one of the simplest carboxylic acid . systematically named ethanoic acid is a colourless liquid organic compound with the chemical formula CH₃COOH (also written as CH₃CO₂H or C₂H₄O₂). When undiluted, it is sometimes called glacial acetic acid. Vingar is no less than 4% acetic acid by volume, making acetic acid the main component of vinegar apart from water. Acetic acid has a distinctive sour taste and pungent smell. In addition to household vinegar, it is mainly produced as a precursor to polyvinyl acetate and cellulose acetate It is classified as a weak acid  only partially dissociated in solution, but concentrated acetic acid is corrosive and can attack the skin.
This acid is an important chemical reagent and industrial chemical useful for the production of various synthetic fibers and other polymeric materials. These polymers include polyethylene terephthalate, used mainly in soft drink bottles; cellulose acetate used mainly for photographic film; and polyvinyl acetate, for wood glue. In households, diluted acetic acid is often used in descaling agents. The food industry uses it (under the food additive code E260) as an acidity regulator.

Acetone ;  an  organic compound with the formula (CH₃)₂CO. It is a colorless, volatile, flammable liquid and is the simplest and smallest ketone.

Acetone is misible with water and serves as an important solvent in its own right, typically for cleaning purposes in laboratories. About 6.7million tonnes were produced worldwide in 2010, mainly for use as a solvent . It is a common building block in organic chemistry Familiar household uses of acetone are as the active ingredient in nail polish remover and as paint thinner.Acetone is produced and disposed of in the human body through normal metabolic processes. It is normally present in blood and urine.

Acetylene;( systematic name Ethyne ) is the chemical compound with the formula C₂H₂. It is a hydrocarbon and the simplest alkyne.this is colorless gas is widely used as a fuel and a chemical building block. It is unstable in its pure form and thus is usually handled as a solution. pure acetylene is odorless, but commercial grades usually have a marked odor due to impurities.

As an alkyne, acetylene is unsaturated because its two carbon atoms are bonded together in a triple bond  The carbon–carbon triple bond places all four atoms in the same straight line, with CCH bond angles of 180°.
Ammonia : 
 Compound of nitrogen and hydrogen with the formula NH3 The simplest pnictogen hydride ammonia is a colourless gas with a characteristic pungent smell. It is a common nitrogenous west particularly among aquatic organisms, and it contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food fertilizer. Ammonia, either directly or indirectly, is also a building block for the synthesis of many pharmaceutical  compound and is used in many commercial cleaning products. It is mainly collected by downward displacement of both air and water. Ammonia is named for the Ammonians, worshipers of the Egyptian god Amun who used ammonium chloride in their rituals.

Ammonium hydroxide: 
 also known as ammonia water, ammonia solution, ammoniacal liquor, ammonia liquor, aqua ammonia, aqueous ammonia, or (inaccurately) ammonia, is a solution of ammonia in water. It can be denoted by the symbols NH₃(aq). Although the name ammonium hydroxide suggests an alkali with composition [NH₄⁺][OH⁻], it is actually impossible to isolate samples of NH₄OH. The ions NH₄⁺ and OH⁻ do not account for a significant fraction of the total amount of ammonia except in extremely dilute solutions.

Azobisisobutyronitrile (abbreviated AIBN): is an organic compound with the formula [(CH₃)₂C(CN)]₂N₂. This white powder is soluble in alcohols and common organic solvents but is insoluble in water. It is often used as a foamer in plastic and rubber and as a radical initiators.


Baeyer's reagents : is an alkaline solution of potassium permanganate; used in organic chemistry as a qualitative test for the presence of unsaturation, such as double bonds.

World's fastest hydrogen sensors

Hii everyone I am going to share some important things on hydrogen as sensors how it can help for us and how it is work its most important part because we all know hydrogen is present very large amount so we can use for so many thing .
 So sensors hydrogen is good thing for current world let see how it work
Credit; a Ph.D. student Ferry Nugroho and his supervisor Christoph Langhamme.

Hydrogen is a clean and renewable energy carrier that can power vehicles, with water as the only emission. Unfortunately, hydrogen gas is highly flammable when mixed with air, so very efficient and effective sensors are needed. Now, researchers from Chalmers University of Technology, Sweden, present the first hydrogen sensors ever to meet the future performance targets for use in hydrogen powered vehicles.

The researchers' ground-breaking results were recently published in the prestigious scientific journal Nature Materials. The discovery is an optical nanosensor encapsulated in a plastic material. The sensor works based on an optical phenomenon – a plasmon – which occurs when metal nanoparticles are illuminated and capture visible light. The sensor simply changes colour when the amount of hydrogen in the environment changes.

The plastic around the tiny sensor is not just for protection, but functions as a key component. It increases the sensor's response time by accelerating the uptake of the hydrogen gas molecules into the metal particles where they can be detected. At the same time, the plastic acts as an effective barrier to the environment, preventing any other molecules from entering and deactivating the sensor. The sensor can therefore work both highly efficiently and undisturbed, enabling it to meet the rigorous demands of the automotive industry – to be capable of detecting 0.1 percent hydrogen in the air in less than a second.

"We have not only developed the world's fastest hydrogen sensor, but also a sensor that is stable over time and does not deactivate. Unlike today's hydrogen sensors,our solution does not need to be recalibrated as often, as it is protected by the plastic," says Ferry Nugroho, a researcher at the Department of Physics at Chalmers.

It was during his time as a Ph.D. student that Ferry Nugroho and his supervisor Christoph Langhammer realised that they were on to something big. After reading a scientific article stating that no one had yet succeeded in achieving the strict response time requirements imposed on hydrogen sensors for future hydrogen cars, they tested their own sensor. They realised that they were only one second from the target – without even trying to optimise it. The plastic, originally intended primarily as a barrier, did the job better than they could have imagined, by also making the sensor faster. The discovery led to an intense period of experimental and theoretical work.

In that situation, there was no stopping us. We wanted to find the ultimate combination of nanoparticles and plastic, understand how they worked together and what made it so fast. Our hard work yielded results. Within just a few months, we achieved the required response time as well as the basic theoretical understanding of what facilitates it," says Ferry Nugroho.

Detecting hydrogen is challenging in many ways. The gas is invisible and odourless, but volatile and extremely flammable. It requires only four percent hydrogen in the air to produce oxyhydrogen gas, sometimes known as knallgas, which ignites at the smallest spark. In order for hydrogen cars and the associated infrastructure of the future to be sufficiently safe, it must therefore be possible to detect extremely small amounts of hydrogen in the air. The sensors need to be quick enough that leaks can be rapidly detected before a fire occurs.

"It feels great to be presenting a sensor that can hopefully be a part of a major breakthrough for hydrogen-powered vehicles. The interest we see in the fuel cell industry is inspiring," says Christoph Langhammer, Professor at Chalmers Department of Physics.

Although the aim is primarily to use hydrogen as an energy carrier, the sensor also presents other possibilities. Highly efficient hydrogen sensors are needed in the electricity network industry, the chemical and nuclear power industry, and can also help improve medical diagnostics.

"The amount of hydrogen gas in our breath can provide answers to, for example, inflammations and food intolerances. We hope that our results can be used on a broad front. This is so much more than a scientific publication," says Christoph Langhammer.

In the long run, the hope is that the sensor can be manufactured in series in an efficient manner, for example using 3-D printer technology.

Facts: The world's fastest hydrogen sensor

• The Chalmers-developed sensor is based on an optical phenomenon – a plasmon – which occurs when metal nanoparticles are illuminated and capture light of a certain wavelength.
• The optical nanosensor contains millions of metal nanoparticles of a palladium-gold alloy, a material which is known for its sponge-like ability to absorb large amounts of hydrogen. The plasmon effect then causes the sensor to change colour when the amount of hydrogen in the environment changes.
• The plastic around the sensor is not only a protection, but also increases the sensor's response time by facilitating hydrogen molecules to penetrate the metal particles more quickly and thus be detected more rapidly. At the same time, the plastic acts as an effective barrier to the environment because no other molecules than hydrogen can reach the nanoparticles, which prevents deactivation.
• The efficiency of the sensor means that it can meet the strict performance targets set by the automotive industry for application in hydrogen vehicles of the future by being capable of detecting 0.1 percent hydrogen in the air in less than one second.
• The research was funded by the Swedish Foundation for Strategic Research, within the framework of the Plastic Plasmonics project.

Carbohydrates in daily life

Carbohydrates are the main source of fuel for your body, making them an important part of your everyday diet. Adequate carbohydrate intake gives you energy for your workout and is essential for normal brain function. Almost all foods provide carbohydrates, with meat, eggs and some types of seafood being the only exceptions.

Immediate Energy 

Carbohydrates break down into glucose, their simplest form, and are utilized for immediate energy. Simple carbohydrates are sugars, such as fruit sugar, or fructose; milk sugar, or lactose; and white table sugar, or sucrose. Simple carbs convert directly into glucose in your small intestine and instantly absorb through intestinal walls. Complex carbs are branched starch molecules. Starch takes longer to metabolize in your gut. When you chew, saliva surrounds starch molecules and breaks them down into smaller maltose molecules. Once maltose, a simple carbohydrate, reaches your small intestine, enzymes break it down further into glucose molecules. From there, glucose absorbs directly into your bloodstream. Since simple carbs digest quickly, they cause your blood glucose to quickly spike, whereas starches may take a while longer to affect your glucose levels.

Energy storage 

Your system automatically uses the glucose it needs right away to supply instant energy and then stores the rest as glycogen in your liver and muscles. Glycogen is a complex polysaccharide carbohydrate that quickly converts back to glucose when carbohydrates are not immediately available. Your body stores enough glycogen to sustain about two hours of vigorous exercise, according to The President's Council on Physical Fitness and Sports.

Carbohydrates in food

Most of your daily calories, between 45 and 65 percent, need to come from carbohydrates to provide enough energy to support everyday functions. Carbohydrates have 4 calories per gram, so if you normally follow a 2,000-calorie diet, you need 225 to 325 grams of carbohydrates each day. Single servings of grain foods, including one slice of bread, a half-cup of mashed potatoes or one-third cup of pasta, provide 15 grams of carbohydrates, the American Dietetic Association reports. A small 4-ounce piece of fruit also has about 15 grams of carbohydrates, while 1-cup of raw non-starchy vegetables, such as spinach and lettuce, offer less than 5 grams of carbohydrates. Milk and yogurt contribute to your daily carbohydrate requirement, offering around 12 grams per 8-ounce serving.

Regulartiy 

Not all carbohydrates provide energy. Fiber is a complex type of carbohydrate that you need in your diet everyday, but it does not break down like other carbohydrates. Instead, fiber passes through your gut, relatively intact, and helps keep you regular. Soluble fiber, from fruits and oats, attracts water and creates a thick sludge. As the sludge passes through, it slows digestion and allows vitamins and minerals to absorb through your intestines. Insoluble fiber, found in vegetables and whole-grain foods, sweeps through your gut like a broom and makes your stools soft and bulky. Both types of fiber are equally important in your diet. You need 14 grams of total fiber for every 1,000 calories in your diet, explains the Dietary Guidelines for Americans 2010. Based on an average 2,000-calorie diet, you need 28 grams of fiber each day.

Isomerism in coordination compound

Isomerism in Coordination Compounds

Two or more different compounds having the same formula are called isomers. Two principal types of isomerism are known among coordination compounds. Each of which can be further subdivided.

1.  Stereoisomerism 

a) Geometrical isomerism
b) Optical isomerism

2. Structural isomerism 

a) Coordination isomerism
b) Ionisation isomerism
c) Hydrate isomerism
d) Linkage isomerism

1. Stereoisomers

Stereoisomers have the same atoms, same sets of bonds, but differ in the relative orientation of these bonds.
Ignoring special cases involving esoteric ligands, then:

Geometric isomers are possible for both square planar and octahedral complexes, but not tetrahedral.
Optical isomers are possible for both tetrahedral and octahedral complexes, but not square planar.
The earliest examples of stereoisomerism involve complexes of Co(III). In 1889, Jorgensen observed purple and green salts of [CoCl₂(en)₂]+, which Werner later correctly identified as the cis- and trans- geometric isomers. In 1911, the first resolution of optical isomers was reported by Werner  and King for the complexes cis-[CoX(NH₃)(en)₂]²⁺, where X=Cl- or Br-.

Geometric Isomers

The number of geometric isomers expected for common stereochemistries are as follows:

Square Planar:

Compound type       No. of isomers
Ma₂b₂                      2 (cis- and trans-)
Mabcd                     3 (use cis- and trans- relations)

here a, b, c, and d refer to monodentate ligands.
A number of examples of these types have been isolated and characterised and they show very different chemical and biological properties. Thus for example, cis-PtCl₂(NH₃)₂ is an anti-cancer agent (cisplatin) whereas the trans- isomer is inactive against cancer (it is toxic), and so not useful in Chemotherapy.

cis- and trans- isomers of [PtCl₂(NH₃)₂]

cis- and trans- refer to the position of 2 groups relative to each other. In the cis-isomer they are "next to each other" i.e. at 90 degrees in relation to the central metal ion, whereas in the trans- isomer they are "opposite each other", i.e. at 180 degrees relative to the central metal ion.

cis- and trans- isomers of [PtCl₂(NH₃)₂]

cis- and trans- refer to the position of 2 groups relative to each other. In the cis-isomer they are "next to each other" i.e. at 90 degrees in relation to the central metal ion, whereas in the trans- isomer they are "opposite each other", i.e. at 180 degrees relative to the central metal ion.

The first report of the three geometric isomers being isolated and characterised for complexes of the type [Mabcd] was by Il'ya Chernyaev in 1928. The example above was reported by Anna Gel'man in 1948.

Question. Does cis-amminebromo-cis-chloropyridineplatinum(II) uniquely identify isomer (ii) above??

Octahedral:

Compound type          No. of isomers
Ma₄b₂                         2 (cis- and trans-)
Ma₃b₃                         2 (fac- and mer-)
MAA₂b₂                     3 (2*cis- and 1 trans-)

here a, and b, represent monodentate ligands and AA is a bidentate ligand.

In the second example, new labels are introduced to reflect the relative positions of the ligands around the octahedral structure. Thus; placing the 3 groups on one face of the octahedral gives rise to the facial isomer and placing the 3 groups around the centre gives rise to the meridional isomer.

fac- and mer- isomers of [RhCl₃(pyr)₃].

[Mabcdef] is expected to give 15 geometric isomers. In the case of [PtBrClI(NO₂)(NH₃)(pyr)], several of these were isolated and characterised by Anna Gel'man and reported in 1956. Optical isomers are possible for each of these 15 forms, making a total of 30 isomers.

The cis- isomer of MAA₂b₂ may also exhibit optical isomerism although we will concentrate largely on optical isomers of the type M(AA)₃ (see below).

Optical Isomers

Optical isomers are related as non-superimposable mirror images and differ in the direction with which they rotate plane-polarised light. These isomers are referred to as enantiomers or enantiomorphs of each other and their non-superimposable structures are described as being asymmetric.
Various methods have been used to denote the absolute configuration of optical isomers such as R or S, Λ or Δ or C and A. The IUPAC rules suggest that for general octahedral complexes C/A scheme is convenient to use and that for bis and tris bidentate complexes the absolute configuration be designated Lambda Λ (left-handed) and Delta Δ (right-handed).
Priorities are assigned for mononuclear coordination systems based on the standard sequence rules developed for enantiomeric carbon compounds by Cahn, Ingold and Prelog (CIP rules). These rules use the coordinating atom to arrange the ligands into a priority order such that the highest atomic number gives the highest priority number (smallest CIP number). For example the hypothetical complex [Co Cl Br I NH₃ NO₂ SCN]^2- would assign the I- as 1, Br as 2, Cl as 3, SCN as 4, NO₂ as 5 and NH₃ as 6.

Here is one isomer where the I and Cl, and Br and NO₂ were found to be trans-to each other.

The reference axis for an octahedral centre is that axis containing the ligating atom of CIP priority 1 and the trans ligating atom of lowest possible priority (highest numerical value). The atoms in the coordination plane perpendicular to the reference axis are viewed from the ligand having that highest priority (CIP priority 1) and the clockwise and anticlockwise sequences of priority numbers are compared. The structure is assigned the symbol C or A, according to whether the clockwise (C) or anticlockwise (A) sequence is lower at the first point of difference. In the example shown above this would be C.

The two optical isomers of [Co(en)₃]³⁺have identical chemical properties and just denoting their absolute configuration does NOT give any information regarding the direction in which they rotate plane-polarised light. This can ONLY be determined from measurement and then the isomers are further distinguished by using the prefixes (-) and (+) depending on whether they rotate left or right.

 To add to the confusion, when measured at the sodium D line (589nm), the tris(1,2-diaminoethane)M(III) complexes (M= Rh(III) and Co(III)) with IDENTICAL absolute configuration, rotate plane polarised light inOPPOSITE directions!
The left-handed (Λ)-[Co(en)₃]³⁺ isomer gives a rotation to the right and therefore corresponds to the (+) isomer.
Since the successful resolution of an entirely inorganic ion (containing no C atoms) hexol only a handful of truly inorganic complexes have been isolated as their optical isomers e.g. (NH4)2pt(S5)3.2H2O
For tetrahedral complexes, R and S would be used in a similar method to tetrahedral Carbon species and although it is predicted that tetrahedral complexes with 4 different ligands should be able to give rise to optical isomers, in general they are too labile and can not be isolated.

2. Structural Isomers

There are several types of this isomerism frequently encountered in coordination chemistry and the following represents some of them.

• a) Coordination isomerism: where compounds containing complex anionic and cationic parts can be thought of as occurring by interchange of some ligands from the cationic part to the anionic part.

one isomer [Co(NH₃)₆] [Cr(C₂O₄)₃]
another isomer [Co(C₂O₄)₃] [Cr(NH₃)₆]

• b) Ionisation isomers: where the isomers can be thought of as occurring because of the formation of different ions in solution.

one isomer [PtBr(NH₃)₃]NO₂ -> NO₂- anions in solution
another isomer [Pt(NO₂)(NH₃)₃]Br -> Br- anions in solution

Notice that both anions are necessary to balance the charge of the complex, and that they differ in that one ion is directly attached to the central metal but the other is not. A very similar type of isomerism results from replacement of a coordinated group by a solvent molecule (Solvate Isomerism). In the case of water, this is called Hydrate isomerism.

• c) Hydrate isomerism: the best known example of this occurs for chromium chloride "CrCl₃.6H₂O" which may contain 4, 5, or 6 coordinated water molecules.

[CrCl₂(H₂O)₄]Cl.2H₂O bright-green
[CrCl(H₂O)₅]Cl₂.H₂O grey-green
[Cr(H₂O)₆]Cl₃ violet

These isomers have very different chemical properties and on reaction with AgNO₃ to test for Cl- ions, would find 1, 2, and 3 Cl- ions in solution respectively.

These isomers have very different chemical properties and on reaction with AgNO₃ to test for Cl- ions, would find 1, 2, and 3 Cl- ions in solution respectively.

• d) Linkage isomerism  occurs with ambidentate ligands. These ligands are capable of coordinating in more than one way. The best known cases involve the monodentate ligands SCN- / NCS- and NO₂^- / ONO^-.

For example:

[Co(ONO)(NH₃)₅]Cl the nitrito isomer -O attached
[Co(NO₂)(NH₃)₅]Cl the nitro isomer - N attached.

Inorganic Nomenclature

As part of this course, you are required to make yourselves familiar with the rules related to inorganic naming

Uses of Coordination Compounds

A brief survey of some of the uses of coordination compounds includes:
l. Dyes and Pigments: Coordination compounds have been used from the earliest times as dyes and pigments, for example madder dye which is red, was used by the ancient Greeks and others. It is a complex of Hydroxyanthraquinone. A more modern example is the pigment copper phthalocyanine, which is blue.
2. Analytical Chemistry: You have already encountered many such uses during the laboratory course.

(a) Colour Tests: Since many complexes are highly coloured they can be used as colourimetric reagents e.g. formation of red 2,2'-bipyridyl and l,l0-phenanthroline complexes as a test for Fe(II)

(b) Gravimetric Analysis: Here chelating ligands are often used to form insoluble complexes e.g. Ni(DMG)₂ and Al(oxine)₃ (see laboratory manual).

(c) Complexometric Titrations and Masking Agents: An example of this is the use of EDTA in the volumetric determination of a wide variety of metal ions in solution, e.g. Zn²⁺, Pb²⁺, Ca²⁺,Co²⁺, Ni²⁺, Cu²⁺, etc. By careful adjustment of the pH and using suitable indicators, mixtures of metals can be analysed, e.g. Bi³⁺in the presence of Pb²⁺ (see laboratory manual). Alternatively, EDTA may be used as a masking agent to remove a metal ion which would interfere with the analysis of a second metal ion present.

3. Sequestering Agents: Related to their use as masking agents is the use of ligands for "sequestering" i.e. for the effective removal of objectionable ions from solution in industrial processing, e.g. EDTA is used to "soften" water. The addition of EDTA to water is used in boilers etc., to prevent "scaling" or build up of insoluble calcium salts.
4. Extraction of Metals: Sometimes certain metals can be leached from their ores by formation of stable complexes e.g. Ag and Au as complexes of cyanide ion.
5. Bio-Inorganic Chemistry: Naturally occurring complexes include haemoglobin, chlorophyll, vitamin B₁₂etc.
EDTA and other complexing agents have been used to speed the elimination of harmful radioactive and other toxic elements from the body. (e.g. Pb²⁺). In these cases soluble metal chelate complexes are formed.
6. Chemo-therapy: an example here is the use of cis- ptCl2(NH3)2 as antitumour drug.

Plasma as state of matter

 Hii  guys , I am going to share   

some idea about  plasma as  a matter  because so many  people  is  still confused  about plasma  is Matter or not? so  don't  worry  in this article  I have try to explain  about plasma  by the theory of

Bose -Einstine condensat as a matter.

A plasma is a hot ionized gas consisting of approximately equal numbers of positively charged ions and negatively charged electrons. The characteristics of plasmas are significantly different from those of ordinary neutral gases so that plasmas are considered a distinct "fourth state of matter." For example, because plasmas are made up of electrically charged particles, they are strongly influenced by electric and magnetic fields (see figure) while neutral gases are not. An example of such influence is the trapping of energetic charged particles along geomagnetic field lines to form the Van Allen radiation belts.

In addition to externally imposed fields, such as the Earth's magnetic field or the interplanetary magnetic field, the plasma is acted upon by electric and magnetic fields created within the plasma itself through localized charge concentrations and electric currents that result from the differential motion of the ions and electrons. The forces exerted by these fields on the charged particles that make up the plasma act over long distances and impart to the particles' behavior a coherent, collective quality that neutral gases do not display. (Despite the existence of localized charge concentrations and electric potentials, a plasma is electrically "quasi-neutral," because, in aggregate, there are approximately equal numbers of positively and negatively charged particles distributed so that their charges cancel.).

The plasma universe

It is estimated that 99% of the matter in the observable universe is in the plasma state...hence the expression "plasma universe." (The phrase "observable universe" is an important qualifier: roughly 90% of the mass of the universe is thought to be contained in "dark matter," the composition and state of which are unknown.) Stars, stellar and extragalactic jets, and the interstellar medium are examples of astrophysical plasmas (see figure). In our solar system, the Sun, the interplanetary medium, the magnetospheres and/or ionospheres of the Earth and other planets, as well as the ionospheres of comets and certain planetary moons all consist of plasmas.

The plasmas of interest to space physicists are extremely tenuous, with densities dramatically lower than those achieved in laboratory vacuums. The density of the best laboratory vacuum is about 10 billion particles per cubic centimeter. In comparison, the density of the densest magnetospheric plasma region, the inner plasmasphere, is only 1000 particles per cubic centimeter, while that of the plasma sheet is less than 1 particle per cubic centimeter.

The temperatures of space plasmas are very high, ranging from several thousand degrees Celsius in the plasmasphere to several million degrees in the ring current. While the temperatures of the "cooler" plasmas of the ionosphere and plasmasphere are typically given in degrees Kelvin, those of the "hotter" magnetospheric plasmas are more commonly expressed in terms of the average kinetic energies of their constitutent particles measured in "electron volts." An electron volt (eV) is the energy that an electron acquires as it is accelerated through a potential difference of one volt and is equivalent to 11,600 degrees Kelvin. Magnetospheric plasmas are often characterized as being "cold" or "hot." Although these labels are quite subjective, they are widely used in the space physics literature. As a rule of thumb, plasmas with temperatures less than about 100 eV are "cold," while those with temperatures ranging from 100 eV to 30 keV can be considered "hot." (Particles with higher energies--such as those that populate the radiation belt--are termed "energetic.")

A Bose-Einstein condensate is a group of atoms cooled to within a hair of absolute zero . When they reach that temperature the atoms are hardly moving relative to each other; they have almost no free energy to do so. At that point, the atoms begin to clump together, and enter the same energy states. They become identical, from a physical point of view, and the whole group starts behaving as though it were a single atom.

To make a Bose-Einstein condensate, you start with a cloud of diffuse gas. Many experiments start with atoms of rubidium. Then you cool it with lasers, using the beams to take energy away from the atoms. After that, to cool them further, scientists use evaporative cooling. "With a [Bose-Einstein condensate], you start from a disordered state, where kinetic energy is greater than potential energy," said Xuedong Hu, a professor of physics at the University at Buffalo. "You cool it down, but it doesn't form a lattice like a solid."

Instead, the atoms fall into the same quantum states, and can't be distinguished from one another. At that point the atoms start obeying what are called Bose-Einstein statistics, which are usually applied to particles you can't tell apart, such as photons.

Theory & discovery

Bose-Einstein condensates were first predicted theoretically by Satyendra Nath Bose (1894-1974), an Indian physicist who also discovered the subatomic particle named for him, the boson. Bose was working on statistical problems in quantum mechanics, and sent his ideas to Albert Einstein. Einstein thought them important enough to get them published. As importantly, Einstein saw that Bose's mathematics — later known as Bose-Einstein statistics — could be applied to atoms as well as light.

What the two found was that ordinarily, atoms have to have certain energies — in fact one of the fundamentals of quantum mechanics is that the energy of an atom or other subatomic particle can't be arbitrary. This is why electrons, for example, have discrete "orbitals" that they have to occupy, and why they give off photons of specific wavelengths when they drop from one orbital, or energy level, to another. But cool the atoms to within billionths of a degree of absolute zero and some atoms begin to fall into the same energy level, becoming indistinguishable.

That's why the atoms in a Bose-Einstein condensate behave like "super atoms." When one tries to measure where they are, instead of seeing discrete atoms one sees more of a fuzzy ball.

Other states of matter all follow the Pauli Exclusion Principle, named for physicist Wolfgang Pauli. Pauli (1900-1958) was an Austrian-born Swiss and American theoretical physicist and one of the pioneers of quantum says that fermions — the kinds of particles that make up matter — can't be in identical quantum states. This is why when two electrons are in the same orbital, their spins have to be opposite so they add up to zero. That in turn is one reason why chemistry works the way it does and one reason atoms can't occupy the same space at the same time. Bose-Einstein condensates break that rule. Though the theory said such states of matter should exist, it wasn't until 1995 that Eric A. Cornell and Carl E. Wieman, both of the Joint Institute for Lab Astrophysics (JILA) in Boulder, Colorado, and Wolfgang Ketterle, of the Massachusetts Institute of Technology, managed to make one, for which they got the 2001 Nobel Prize in Physics.

In July 2018, an experiment aboard the International Space Station cooled a cloud of rubidium atoms to ten-millionth of a degree above absolute zero.