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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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Lone Pair

Pair of electrons residing on one atom and not shared by other atoms, unshared pair.

Total Ionic Equation

Equation for a chemical reaction written to show the predominant form of all species in aqueous solution or in contact with water.

Particulate Matter

Fine divided solid particles suspended in polluted air.

Capillary Action

The drawing of a liquid up the inside of a small-bore tube when adhesive forces exceed cohesive forces, or the depression of the surface of the liquid when cohesive forces exceed the adhesive forces.

Mass Spectrometer

An instrument that measures the charge-to-mass ratio of charged particles.

Iron

Discovered : known to ancient civilisations.

Origin : The name comes from the Anglo-Saxon ‘iren’, and the symbol from the Latin ‘ferrum’, meaning iron.
Description :Iron is an enigma - it rusts easily and yet is the most important of all metals, world production exceeds 700 million tons a year. Small amounts of carbon are added to iron to produce steel and when chromium.
is added to this, the result is non-corroding stainless steel (small amounts of nickel may also be added). Iron is also an essential element for all forms of life. The average human contains about 4 grams, much of which circulates as haemoglobin in the blood, the job of which is to carry oxygen from our lungs to where it is needed. If the diet does not contain 10 milligrams a day, anaemia will eventually develop. Foods such as liver, kidney, molasses, brewer’s yeast, cocoa and liquorice contain a lot of iron.
Atomic No:26 Mass No:56

Effective Nuclear Charge

The nuclear charge experienced by the outermost electrons of an atom, the actual nuclear charge minus the effects of shielding due to inner-shell electrons.
Example: Set of dx2-y2 and dz2 orbitals, those d orbitals within a set with lobes directed along the x-, y-, and z-axes.

Curie (Ci)

The basic unit used to describe the intensity of radioactivity in a sample of material. One curie equals 37 billion disintegrations per second or approximately the amount of radioactivty given off by 1 gram of radium.

Hybridization

Mixing a set of atomic orbitals to form a new set of atomic orbitals with the same total electron capacity and with properties and energies intermediate between those of the original unhybridized orbitals.

Where is ozone used?

Ozone is widely used in various areas of our life. It is used in medicine, in industry, in everyday life.