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A brownish smog occurring in urban areas receiving large amounts of sunlight, caused by photochemical (light-induced) reactions among nitrogen oxides, hydrocarbons and other components of polluted air that produce photochemical oxidants.

 

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Open Sextet

Refers to species that have only six electrons in the highest energy level of the central element (many Lewis acids).

Osmosis

The process by which solvent molecules pass through a semipermable membrane from a dilute solution into a more concentrated solution.

 

Bronsted-Lowry Acid

A proton donor.

Chemical Bonds

The attractive forces that hold atoms together in elements or compounds.

Solvent

The dispersing medium of a solution.

Helium

Discovered : by Sir William Ramsay in London, and independently by P.T. Cleve and N.A. Langlet in Uppsala, Sweden in 1895.
Origin : The name is derived from the Greek ‘helios’,sun.
Description :A colourless, odourless gas that is totally unreactive. It is extracted from natural gas wells, some of which contain gas that is 7% helium. It is used in deep sea diving for balloons and, as liquid helium, for low temperature research. The Earth’s atmosphere contains 5 parts per million by volume, totalling 400 million tons, but it is not worth extracting it from this source at present.
Atomic No:2 MAss No:4

Miscibility

The ability of one liquid to mix with (dissolve in) another liquid.

Alpha (a) Particle

Helium ion with 2+ charge, an assembly of two protons and two neutrons.

Graham's Law

The rates of effusion of gases are inversely proportional to the square roots of their molecular weights or densities.

Forbidden Zone

A relatively large energy separation between an insulator's highest filled electron energy band and the next higher energy vacant band. Beginning in the fourth energy level, a set of seven degenerate orbitals per energy level, higher in energy than s, p, and d orbitals of the same energy level.