Refers to the occurrence of an element in an uncombined or free state in nature.
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Compound produced by dehydration of a carbonic acid. General formula is R--C--O--C--R. Chemical compound that reacts with water to form an acid and are usually oxides of nonmetallic elements.
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.
Discovered : known to ancient civilisations
Origin : The name is derived from 'Cuprum', the Latin name for Cyprus.
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
A vertical column in the periodic table, also called a family.
The degree of polymerization, the average number of monomer units per polymer unit.
Ability of a substance to exhibit amphiprotism by accepting donated protons.
A substance that produces OH (aq) ions in aqueous solution. Strong soluable bases are soluble in water and are completely dissociated. Weak bases ionize only slightly.
Amine in which the nitrogen is part of a ring.
To estimate the value of a result outside the range of a series of known values. Technique used in standard additions calibration procedure.
Region or volume in space in which the probability of finding electrons is highest.
Two or more forms of atoms of the same element with different masses, atoms containing the same number of protons but different numbers of neutrons.
Poor electric and heat conductor.
The properties of the elements are periodic functions of their atomic numbers.
Adverse health effects resulting from skin exposure ot a substance.
The amount of water that would absorb the same amount of heat as the calorimeter per degree temperature increase.
Hydrolysis of esters in the presence of strong soluable bases.
The number of moles of a component of a mixture divided by the total number of moles in the mixture.
Reactions in which two compounds react to form two new compounds, with no changes in oxidation number. Reactions in which the ions of two compounds exchange partners.
Radius of an atom.