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All orbitals of a given sublevel must be occupied by single electrons before pairing begins.

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Electrode at which reduction occurs in a cathode ray tube, the negative electrode.

Specific Gravity

The ratio of the density of a substance to the density of water.

Critical Pressure

The pressure required to liquefy a gas (vapor) at its critical temperature.

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.


A substance that produces H+(aq) ions in aqueous solution. Strong acids ionize completely or almost completely in dilute aqueous solution. Weak acids ionize only slightly. Chemicals or substances having the property of an acid are said to be acidic.

Binary Acid

A binary compound in which H is bonded to one or more of the more electronegative nonmetals.


The undesirable overgrowth of vegetation caused by high concentrates of plant nutrients in bodies of water.


The number of repeating corresponding points on a wave that pass a given observation point per unit time.

Fossil Fuels

Substances consisting largely of hydrocarbons, derived from decay of organic materials under geological conditions of high pressure and temperature (metamorphism) include coal, petroleum, natural gas, peat and oil shale.  For further information see Fuel Chemistry

Geometrical Isomers

Compounds with different arrangements of groups on either side of a bond with restricted rotation, such as a double bond or a single bond in a ring, for example cis-trans isomers of certain alkenes. Stereoisomers that are not mirror images of each other, also known as position isomers.