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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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D -Transition elements (metals)

B Group elements except IIB in the periodic table, sometimes called simply transition elements EX. Fe, Ni, Cu, Ti .
For further information see Metals.

Natural Radioactivity

Spontaneous decomposition of an atom.

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

Saccharide

An organic compound containing a sugar or sugars.

Linkage Isomers

Isomers in which a particular ligand bonds to a metal ion through different donor atoms.

 

Liquid Aerosol

Colloidal suspension of liquid in gas.

Hydration Energy

The energy change accompanying the hydration of a mole of gase and ions.

Density

Density is the ratio b/w Mass and Volume: D=M/V

Absolute Zero

The zero point on the absolute temperature scale, -273.15°C or 0 K, theoretically, the temperature at which molecular motion ceases. The concept of an absolute zero temperature was first deduced from experiments with gases. When a fixed volume of gas is cooled, its pressure decreases with its temperature. Absolute zero physically possesses quantum mechanical zero-point energy.

London Forces

Very weak and very short-range attractive forces between short-lived temporary (induced) dipoles, also called dispersion Forces.