noble gases

In chemistry, the term Van der Waals force originally referred to all forms of intermolecular forces; however, in modern usage it tends to refer to intermolecular forces that deal with forces due to the polarization of molecules. Forces that deal with fixed or angle averaged dipoles (Keesom forces) and free or rotation dipoles (Debye forces) as well as shifts in electron cloud distribution (London Forces) are named after the Dutch chemist Johannes Diderik van der Waals who first documented these interactions. The Lennard-Jones potential is often used as an approximate mo ...

Including:

• Van der Waals force - London dispersion force
• Van der Waals force - Relation to the Casimir effect

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The Fullerenes are recently-discovered allotropes of carbon. They are molecules composed entirely of carbon, which take the form of a hollow sphere, ellipsoid, or tube. Spherical fullerenes are sometimes called buckyballs, while cylindrical fullerenes are called buckytubes or nanotubes. Fullerene - Naming. The molecule was named for Richard Buckminster Fuller, a noted architect who popularized the geodesic dome. Since buckminsterfullerenes have a similar shape to that sort of dome, the ...

Including:

• Fullerene - Naming
• Fullerene - Buckminsterfullerene
• Fullerene - Prediction and discovery
• Fullerene - Properties
• Fullerene - Possible dangers
• Fullerene - Fullerene extract mixture C₆₀/C₇₀ solubility
• Fullerene - Diffraction of fullerene
• Fullerene - Notes
• Fullerene - Mathematics of Fullerenes
• Fullerene - Media

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Van der Waals bonding, also known as London force, instantaneous dipole effect, and induced dipole interaction, is an intermolecular force or interatomic force that causes an attraction between temporarily induced dipoles in nonpolar molecules and atoms because of assymetrical distribution of electrons due to their movement. Van der Waals bonding is much weaker than both ionic and covalent bonding, and usually weaker than hydrogen bonds. Van der Waals bonding is the sole process by which noble gases are attracted to each other, and the dominant form of interaction between ele ...

Including:

• Van der Waals bonding - Related Topics

Read more here: » Van der Waals bonding: Encyclopedia - Van der Waals bonding

Internal energy U cannot be measured directly. There is an arbitrary zero reference value, just as there is for gravitational potential energy. Only its change ΔU can be measured, and this is where Q is heat added to the system (measured in joules in SI) ±W is work done on the system (measured in joules in SI) ΔU is the value of the internal energy after a process minus its value before, independent of the arbitrary sign convention used for the second ter ...

See also:

Internal energy, Internal energy - Measurement

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The accident had a number of primary causes, related both to technical malfunction and human error. The accident in the TMI-2 reactor (the plant had two reactors; TMI-1 was down for refueling at the time) began when the plant's main feedwater pumps in the secondary non-nuclear cooling system failed at about 4:00 a.m. on March 28, 1979. This failure was due to either a mechanical or electrical failure in the condensate system and caused a reduction in feedwater flow which prevented the steam generators from removing heat. The auxiliary (backu ...

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Three Mile Island, Three Mile Island - Three Mile Island nuclear accident, Three Mile Island - Aftermath, Three Mile Island - The China Syndrome, Three Mile Island - Notes

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Information about the structure of Earth's deep interior can be acquired only indirectly by geophysical and geochemical methods. For the investigation of the Iceland Plume as well as of other plumes, gravimetric, geoid and in particular seismological methods along with geochemical analyses of erupted lavas have proven especially useful. Numerical models of the geodynamical processes attempt to merge these observations into a consistent ...

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Iceland plume, Iceland plume - Geological history, Iceland plume - Geophysical and geochemical observations, Iceland plume - Seismology, Iceland plume - Geochemistry, Iceland plume - Gravimetry/Geoid, Iceland plume - Geodynamics, Iceland plume - Alternative models, Iceland plume - Literature

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Doping fullerenes with electro positive metals takes place in an arc reactor or via laser evaporation. The metals can be transition metals like scandium, yttrium as well as lanthanides like lanthanum and cerium. Also possible are endohedral complexes with elements of the alkaline earth metals like barium and strontium and alkali metals like potassium and tetravalent metals like uranium, zirconium and hafnium. The synthesis in the arc reactor is however unspecific. Besides unfilled Fullerenes, endohedral metallofullerenes develop with differe ...

See also:

Endohedral fullerenes, Endohedral fullerenes - Endohedral metallofullerenes, Endohedral fullerenes - Non-metal doped fullerenes

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Because of the non-reactive properties of inert gases they are often useful to prevent undesirable chemical reactions from taking place. For example molecular nitrogen, a molecular inert gas, is often used in food packaging to ensure that food does not spoil in transit since no bacteria or fungi can flourish without the reactive gases oxygen or carbon dioxide, which the molecular nitrogen displaces, since most extant cells on Earth require the reactions which these gases are involved in to function. Most importantly since molecular nitrogen ...

See also:

Inert gas, Inert gas - Production, Inert gas - Applications

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Mercury was known to the ancient Chinese and Hindus and was found in Egyptian tombs that date from 1500 BCE. In China, India and Tibet, mercury use was thought to prolong life, heal fractures, and maintain generally good health. The ancient Greeks used mercury in ointments and the Romans used it in cosmetics. By 500 BCE mercury was used to make amalgams with other metals. The Indian word for alchemy is Rassayana which means ‘the way of mercury.’ Alchemists often thought of mercury as the first matter from which all metals w ...

See also:

Mercury element, Mercury element - Applications, Mercury element - History, Mercury element - Dentistry, Mercury element - Medicine, Mercury element - Mineral occurrence, Mercury element - Compounds, Mercury element - Isotopes, Mercury element - Occurrence in the environment, Mercury element - Health and Environmental Effects, Mercury element - Precautions and Regulation

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Mercury was known to the ancient Chinese and Hindus and was found in Egyptian tombs that date from 1500 BC In China, India and Tibet, mercury use was thought to prolong life, heal fractures, and maintain generally good health. The ancient Greeks used mercury in ointments and the Romans used it in cosmetics. By 500 BC mercury was used to make amalgams with other metals. The Indian word for alchemy is Rassayana which means ‘the way of mercury.’ Alchemists often thought of mercury as the first matter from which all metals were ...

See also:

Mercury element, Mercury element - Applications, Mercury element - History, Mercury element - Dentistry, Mercury element - Medicine, Mercury element - Mineral occurrence, Mercury element - Compounds, Mercury element - Isotopes, Mercury element - Occurrence in the environment, Mercury element - Health and Environmental Effects, Mercury element - Precautions and regulation, Mercury element - Occupational exposure, Mercury element - Mercury in fish, Mercury element - Release of mercury into the environment, Mercury element - Mercury and aluminum

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In this example, moles are used to calculate the mass of CO2 given off when 1 g of ethane is burnt. The equation for this chemical reaction is: 7 O2 + 2 C2H6 → 4 CO2 + 6 H2O Here, 7 moles of oxygen react with 2 moles of ethane to give 4 moles of carbon dioxide and 6 moles of water. Notice that the number of moles does not need to balance on either side of the equation. This is because a mole does not count mass or the number of atoms involved, ...

See also:

Mole unit, Mole unit - Definition, Mole unit - Elementary entities, Mole unit - History, Mole unit - Utility of moles, Mole unit - Example calculation

Read more here: » Mole unit: Encyclopedia II - Mole unit - Example calculation

Liquid-liquid extraction - Solvation mechanism. Using solvent extraction it is possible to extract uranium, plutonium, or thorium from acid solutions. One solvent used for this purpose is the organophosphate tri-n-butyl phosphate. The PUREX process is commonly used in nuclear reprocessing uses a mixture of tri-n-butyl phosphate and an inert hydrocarbon (kerocene), the uranium(VI) are extracted from strong nitric acid and are back-extracted (stripped) using weak nitric acid. An organic soluble uranium complex [UO< ...

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Liquid-liquid extraction, Liquid-liquid extraction - Distribution ratio, Liquid-liquid extraction - One big batch of solvent or several smaller batchs ?, Liquid-liquid extraction - Separation factors, Liquid-liquid extraction - Decontamination factor, Liquid-liquid extraction - Slopes of graphs, Liquid-liquid extraction - Batchwise single stage extractions, Liquid-liquid extraction - Multistage countercurrent continuous processes, Liquid-liquid extraction - Extraction without chemical change, Liquid-liquid extraction - Extraction with chemical change, Liquid-liquid extraction - Solvation mechanism, Liquid-liquid extraction - Ion exchange mechanism, Liquid-liquid extraction - Ion pair extraction, Liquid-liquid extraction - Kinetics of extraction, Liquid-liquid extraction - Aqueous complexing agents, Liquid-liquid extraction - Industrial process design, Liquid-liquid extraction - Equipment, Liquid-liquid extraction - Terms

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Dmitri Mendeleev, also spelt Dmitry Mendeleyev, middle name (patronymic) Ivanovich, a Siberian-born Russian chemist, was the first scientist to make a periodic table much like the one we use today. Mendeleev arranged the elements in a table ordered by atomic mass. On March 6, 1869, a formal presentation was made to the Russian Chemical Society, entitled The Dependence Between the Properties of the Atomic Weights of the Elements. His table was published in an obscure Russian journal but quickly republished in a German journal, Zeits ...

See also:

History of the periodic table, History of the periodic table - In the beginning, History of the periodic table - Antoine-Laurent de Lavoisier, History of the periodic table - Alexandre-Emile Béguyer de Chancourtois, History of the periodic table - John Newlands' Octaves, History of the periodic table - The first periodic table, History of the periodic table - Henry Moseley, History of the periodic table - Walter Russell

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Mercury was known to the ancient Chinese and Hindus and was found in Egyptian tombs that date from 1500 BCE. In China, India and Tibet, mercury use was thought to prolong life, heal fractures, and maintain generally good health. The ancient Greeks used mercury in ointments and the Romans used it in cosmetics. By 500 BCE mercury was used to make amalgams with other metals. The Indian word for alchemy is Rassayana which means ‘the way of mercury.’ Alchemists often thought of mercury as the first matter from which all metals w ...

See also:

Mercury element, Mercury element - Applications, Mercury element - History, Mercury element - Dentistry, Mercury element - Medicine, Mercury element - Mineral occurrence, Mercury element - Compounds, Mercury element - Isotopes, Mercury element - Occurrence in the environment, Mercury element - Health and Environmental Effects, Mercury element - Precautions and regulation, Mercury element - Occupational exposure, Mercury element - Mercury in fish, Mercury element - Release of mercury into the environment, Mercury element - Mercury and aluminum

Read more here: » Mercury element: Encyclopedia II - Mercury element - History

After completing an apprenticeship to a confectioner in 1876, Milton Snavely Hershey founded a candy shop in Philadelphia, which failed six years later. After trying unsuccessfully to manufacture candy in New York, Hershey returned to Pennsylvania, where he founded the Lancaster Caramel Company, whose use of fresh milk in caramels proved successful. In 1900, Hershey sold his caramel company for $1,000,000 ($22,155,604 in today's cu ...

See also:

The Hershey Company, The Hershey Company - History of Hershey's, The Hershey Company - Chocolate, The Hershey Company - Philanthropic giving, The Hershey Company - Helen Caldicott and the Hershey Company

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Most molecules are much too small to be seen with the naked eye, but there are exceptions. DNA, a macromolecule, can reach macroscopic sizes. The smallest molecule is the hydrogen molecule. The interatomic distance is 0.15 nanometres (1.5 Å). But the size of its electron cloud is difficult to define precisely. Under standard conditions molecules have a dimension of a few to a few dozen Å. ...

See also:

Molecule, Molecule - History, Molecule - Chemical bond, Molecule - Size, Molecule - Empirical formula, Molecule - Chemical formula, Molecule - Molecular geometry, Molecule - Molecular spectroscopy, Molecule - Related lists

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In this example, moles are used to calculate the mass of CO2 given off when 1 g of ethane is burnt. The equation for this chemical reaction is: 7 O2 + 2 C2H6 → 4 CO2 + 6 H2O that is, 7 molecules of oxygen react with 2 molecules of ethane to give 4 molecules of carbon dioxide and 6 molecules of water. The first thing is to figure out how many molecules of ethane were burnt. We know that it was just enough to make 1 g, ...

See also:

Mole unit, Mole unit - Definition, Mole unit - Elementary entities, Mole unit - History, Mole unit - Utility of moles, Mole unit - Example calculation

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Plasma displays are bright (1000 lx or higher for the module), have a wide color gamut, and can be produced in fairly large sizes, up to 200 cm (80 inches) diagonally. They have a very high "dark-room" contrast, creating the "perfect black" desirable for watching movies. The display panel is only 6 cm (2 1/2 inches) thick, while the total thickness, including electronics, is less than 10 cm (4 inches). Plasma displays use as much power per square meter as a CRT or an AMLCD television; in 2004 the cost has come down to US$1900 or less for the ...

See also:

Plasma display, Plasma display - History, Plasma display - General characteristics, Plasma display - Functional details, Plasma display - Contrast ratio claims

Read more here: » Plasma display: Encyclopedia II - Plasma display - General characteristics

Pure fluorine (F2) is a corrosive pale yellow gas that is a powerful oxidizing agent. It is the most reactive and electronegative of all the elements, and readily forms compounds with most other elements. Fluorine even combines with the noble gases krypton, xenon, and radon. Even in dark, cool conditions, fluorine reacts explosively with hydrogen. It is so reactive that glass, metals, and even water, as well as other substances, burn with a bright flame in a jet of fluorine gas. It is far too reactive to be found in elemental form ...

See also:

Fluorine, Fluorine - Notable characteristics, Fluorine - Applications, Fluorine - History, Fluorine - Precautions, Fluorine - Preparation, Fluorine - Compounds

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In 1871, Mendeleev predicted, from the gaps in his newly-devised periodic table, that there should be three as yet undiscovered elements, which he named eka-boron, eka-aluminium, and eka-silicon. With Mendeleev's prediction of their existence and approximate chemical properties, the missing elements were found by French, Scandinavian, and German chemists, and named for their countries of discovery, as gallium, scandium, and germanium: The 'didy ...

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Discoveries of the chemical elements, Discoveries of the chemical elements - Spectroscopic discoveries, Discoveries of the chemical elements - The Periodic table and the prediction of new elements, Discoveries of the chemical elements - The synthetic elements

Read more here: » Discoveries of the chemical elements: Encyclopedia II - Discoveries of the chemical elements - The Periodic table and the prediction of new elements