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The arrangement of atoms (not lone pairs of electrons) about the central atom of a polyatomic ion.

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  • What are Compound Microscopes?

    Most of the microscopes used today are compound. A compound microscope features two or more lenses. A hollow cylinder called the tube connects the two lenses. The top lens, the one people look through, is called the eyepiece. The bottom lens is known as the objective lens. Below the two lenses is...

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    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.

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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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    Metals have been used by people since ancient times. All the time the process of obtaining them was improved, useful alloys of various metals appeared. Let’s look at interesting facts about metals.

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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.

Alkaline Earth Metals

Group IIA metals


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

Downs Cell

Electrolytic cell for the commercial electrolysis of molten sodium chloride. For further information see Electrochemistry or Fuel Cells.

Diagonal Similarities

Refers to chemical similarities in the Periodic Table of elements of Period 2 to elements of Period 3 one group to the right, especially evident toward the left of the periodic table.

Combination Reaction

Reaction in which two substances (elements or compounds) combine to form one compound.


The separation of a liquid mixture into its components on the basis of differences in boiling points. The process in which components of a mixture are separated by boiling away the more volitile liquid.

Molecular Orbital Theory

A theory of chemical bonding based upon the postulated existence of molecular orbitals.

Daughter Nuclide

Nuclide that is produced in a nuclear decay.



A liquid as defined by NFPD and DOT as having a flash point below 37.8°C (100°F).