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Amount of energy that holds a crystal together, the energy change when a mole of solid is formed from its constituent molecules or ions (for ionic compounds) in their gaseous state.

The energy charge when one mole of formula units of a crystalline solid is formed from its ions, atoms, or molecules in the gas phase, always negative.

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Heterogeneous Mixture

A mixture that does not have uniform composition and properties throughout.

Dissociation

In aqueous solution, the process in which a solid ionic compound separates into its ions.

Voltage

Potential difference between two electrodes, a measure of the chemical potential for a redox reaction to occur.

Coordination Compound or Complex

A compound containing coordinate covalent bonds.

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

Polar Bond

Covalent bond in which there is an unsymmetrical distribution of electron density.

Explosive limits

The range of concentrations over which a flammable vapour mixed with proper ratios of air will ignite or explode if a source of ignitions is provided.

Actinides

Elements 89 to 103 (between lawrencium and actinium) on the periodic table. Only the first four have been found in nature in appreciable amounts. The remainder have been produced synthetically.

Formula Unit

The smallest repeating unit of a substance. The molecule for nonionic substances

Free Radical

A highly reactive chemical species carrying no charge and having a single unpaired electron in an orbital.