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The concept in which two or more equivalent dot formulas for the same arrangement of atoms (resonance structures) are necessary to describe the bonding in a molecule or ion.

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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.

Ideal Gas

A hypothetical gas that obeys exactly all postulates of the kinetic-molecular theory.


Binding Energy (nuclear binding energy)

The energy equivalent (E = mc^2) of the mass deficiency of an atom.  where: E = is the energy in joules, m is the mass in kilograms, and c is the speed of light in m/s^2

Downs Cell

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


Different substances that have the same formula.

Photoelectric Effect

Emission of an electron from the surface of a metal caused by impinging electromagnetic radiation of certain minimum energy, current increases with increasing intensity of radiation.


All Chemicals - Chemical Glossary

The Chemical Glossary currently has 651 chemical entries. You may search the Chemical Glossary by entering the keyword in the search box or by browsing the entire chemical glossary by letter in alphabetical order.

Shielding Effect

Electrons in filled sets of s , p orbitals between the nucleus and outer shell electrons shield the outer shell electrons somewhat from the effect of protons in the nucleus, also called screening effect.

Square Planar Complex

Complex in which the metal is in the center of a square plane, with ligand donor atoms at each of the four corners.

xenon hexafluoride

A colorless, crystalline compound, XeF6, that melts at 50°C to a yellow liquid, and boils at 75°C.