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A reaction in which an atom or a group of atoms is replaced by another atom or group of atoms.

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  • Gas of rotten eggs

    If you happen to break a rotten egg, then you know the smell of hydrogen sulfide, because the stench of the spoiled egg depends on of its presence in rotting protein substances.

  • Varieties of garnet minerals

    The most famous type of garnet stone is pyrope (flaming). This is the "oldest of garnets", with a dense red color, similar to the grain of an edible garnet. Pyrope has a variety called rhodolite - a stone of dense pink or pink-purple color, which sometimes has the alexandrite effect and is used in...

  • Ozone

    We breathe 24 hours a day, 7 days a week, consuming about 25 kg of air every day. It turns out that we practically predetermine our health by the air we breathe.

  • Why do copper products change color, and what is the name of the process?

    Probably, every person wants to know, why over time the copper turns green and becomes bloomed. This is easy to explain: that film is called patina.

  • Features of the Scanning Tunneling Microscope

    The scanning tunneling microscope (STM) invented by Heinrich Rohrer and Gerd Binnig in the 1980s still manages to do a great job today and competes with more advanced microscope types. The scanning tunneling microscope is used for studying the surface atoms that are found on various materials. The...

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Spectrochemical Series

Arrangement of ligands in order of increasing ligand field strength.


A unit of energy in the SI system. One joule is 1 kg. m2/s2 which is also 0.2390 calorie.

Mass Spectrometer

An instrument that measures the charge-to-mass ratio of charged particles.

Reversible Reaction

Reactions that do not go to completion and occur in both the forward and reverse direction.

Differential Scanning Calorimetry (DSC)

A technique for measuring the temperature, direction, and magnitude of thermal transitions in a sample material by heating/cooling and comparing the amount of energy required to maintain its rate of temperature increase or decrease with an inert reference material under similar conditions.


A rare trivalent metallic element, found in gadolinite and other minerals. Symbol: Y, at. wt.: 88.905, at. no.: 39, sp. gr.: 4.47. Cf."rare-earth element."

Yttrium has a silver-metallic luster and is relatively stable in air unless finely divided. Turnings of the metal, however, ignite in air if their temperature exceeds 400oC. Yttrium oxide is one of the most important compounds of yttrium and accounts for the largest use. It is widely used in making YVO4 europium, and Y2O3 europium phosphors to give the red color in color television tubes.

Monoprotic Acid

Acid that can form only one hydronium ion per molecule, may be strong or weak. Acid that contains one ionizable hydrogen atom per formula unit.

Emulsifying Agent

A sustance that coats the particles of the dispersed phase and prevents coagulation of colloidal particles, an emulsifier.

Chemical Equation

Description of a chemical reaction by placing the formulas of the reactants on the left and the formulas of products on the right of an arrow.

Semipermable Membrane

A thin partition between two solutions through which certain molecules can pass but others cannot.