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A substance such as hydrogen, deuterium, oxygen or paraffin capable of slowing fast nuetrons upon collision.

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    The scanning tunneling microscope (STM) invented by Heinrich Rohrer and Gerd Binnig in the 1980s still manages to do a great job today and competes with more advanced microscope types. The scanning tunneling microscope is used for studying the surface atoms that are found on various materials. The...

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First Law of Thermodynamics

The total amount of energy in the universe is constant (also known as the Law of Conservation of Energy) energy is neither created nor destroyed in ordinary chemical reactions and physical changes.

Rate-determining Step

The slowest step in a mechanism, the step that determines the overall rate of reaction.


Combination of symbols that indicates the chemical composition of a substance.


Aryl Group

Group of atoms remaining after a hydrogen atom is removed from the aromatic system.

Binary Acid

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

Heterocyclic Amine

Amine in which the nitrogen is part of a ring.

Cloud Chamber

A device for observing the paths of speeding particiles as vapor molecules condense on them to form foglike tracks.


Plating a metal onto a (cathodic) surface by electrolysis.

Heat of Fusion

The amount of heat required to melt one gram of solid at its melting point with no change in temperature. Usually expressed in J/g. The molar heat of fusion is the amount of heat required to melt one mole of a solid at its melting point with no change in temperature and is usually expressed in kJ/mol.


Discovered : by Henry Cavendish in 1766.
Isolated in London, UK.
Origin : The name is derived from the Greek ‘hydro genes’, meaning water forming.
Description :A colourless, odourless gas that burns and can form an explosive mixture with air. It is currently manufactured from methane gas, but is also produced by the electrolysis of water and aqueous salts. The gas is used to make such key materials as ammonia, cyclohexane and methanol, which are intermediates in the production of fertilisers, plastics and pharmaceuticals. Some see hydrogen gas as the clean fuel of the future - generated from water and returning to water when it is oxidised. Hydrogen-powered fuel cells are increasingly being seen as pollution-free sources of energy.