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A property that depends upon the amount of material in a sample.

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    Diamond is a crystalline modification of pure carbon formed in the deep interior of the Earth, in the upper mantle at depths of more than 80-100 kilometers, at exceptionally high pressure and temperature. It is the most precious stone, the hardest and most wear-resistant mineral, the most...

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    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...

  • 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...

  • The most expensive metal in the world

    Do you think the most expensive metal is gold? No! On earth there are more valuable metals. But we need to divide the value of metals that occur in nature, and metals - isotopes, which are obtained in special laboratories. Let’s look at natural metals first.

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The time required for half of a reactant to be converted into product(s). The time required for half of a given sample to undergo radioactive decay.


Refers to substances that crystallize in more than one crystalline arrangement.

Valence Electrons

Outermost electrons of atoms, usually those involved in bonding.


Elements 89 to 103 (between lawrencium and actinium) on the periodic table. Only the first four have been found in nature in appreciable amounts. The remainder have been produced synthetically.

Ionic Compounds

Compounds containing predominantly ionic bonding.


Hydrated sulfates of the general formula M+M3+(SO4)2.12H2).

Molecular Equation

Equation for a chemical reaction in which all formulas are written as if all substances existed as molecules, only complete formulas are used.

Ideal Gas Law

The product of pressure and the volume of an ideal gas is directly proportional to the number of moles of the gas and the absolute temperature.

Nonbonding Orbital

A molecular orbital derived only from an atomic orbital of one atom, lends neither stability nor instability to a molecule or ion when populated with electrons.

Continuous Spectrum

Spectrum that contains all wave-lengths in a specified region of the electromagnetic spectrum.