Thus carbonates CaQ 5 cyanides KCN carbides CaC 5 as also carbon monoxide CO

Thus carbonates caq 5 cyanides kcn carbides cac 5 as

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Thus carbonates (CaQ) 5 ), cyanides (KCN), carbides (CaC 5 ) as also carbon monoxide (CO) and carbon dioxide (00 1 ) are treated as Inorganic compounds, while they all contain carbon. Since the various organic compounds known contained carbon and were also invariably associated with hydrogen, these could well be considered as divided from hydrocarbons. Thus a more precise definition of organic chemistry would be - "the study of hydrocarbons and the corn- pounds which could be thought of as their derivatives." WHY SflJDY ORGANIC CHEMISTRY AS A SEPARATE BRANCH 7 Having established that organic compounds could be obtained by ordinary laboratory processes and that they obeyed the same fundamental laws which hold for inorganic compounds, there was hardly any justification for their separate study. However, there are marked differences between the composition, structure and behaviour of organic and inorganic compounds which make their study as a separate branch of chemistry more practical and fruitful. The main reasons advanced for it are (I) Large number of compounds. No one today knows exactly how many organic com- pounds are present in nature. The number of compounds which have been actually prepared or isolated in the laboratory is about four million. This far exceeds the total number of inorganic compounds which is nearly 50,000 only. If the study of four million carbon compounds were included with that of carbon under Inorganic Chemistry, it would throw the subject out of balance (2) BaIt of relatively few elements. Organic compounds are built from relatively few elements. The elements most frequently encountered in organic chemistry are hydrogen, oxygen, nitrogen, sulphur, phosphorus, and halogens. In contrast, inorganic compounds are formed from any of 105 elements known. (3) ?.ctlesaJ group. as basis of claI1cstloo. Organic molecules contain active atoms or groups of atoms which determine their chemical behaviour. These are called functional groups. Thus organic compounds with similar functional groups display similar properties and form a 'class'. There are many such classes of compounds e.g., alcohols (—OH), aldehydes (—CHO), carboxylic acids (—COOH), amines (—NH 1 ), etc. This classification based on functional groups makes the study of organic chemistry simple and easier, Most of the inorganic substances which have been studied arc either acids, bases or sails. (4) Molqmles formed by osialeat bosdiap. Organic molecules are characterised by the presence of covalent bondings. The inorganic salts contain ionic or electrovalent bondings. Thus, H H-—H Na Im couhet beading.) (sodium cbndd. be ina boo Many differences in the properties of organic and inorganic compounds are due to different types of bondings present in their molecules. (5) Uique cboractmidc of Carbos to .dp Catdea'. In fact, carbon is unique among the elements. Its atoms possess the wonderful capacity to unite with cads other by means of stable covalent bonds. Carbon atoms joined each to each in straight chains, branched chains or rings of all size., form a large number of
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