9.1 Physical properties of metals
9.2 Saturated and unsaturated hydrocarbons
9.3 Functional Groups in Organic Compounds
9.4 Nomenclature of organic compounds
9.5 Chemical properties of carbon compounds

        At the beginning of the 19th century, compounds directly or indirectly obtained from plants and animals were regarded as organic compounds. Compounds obtained from minerals were termed as inorganic compounds.

Activity 9.1
Classify the following compounds used by you in terms of their origin (plants, animals, inorganic) : oil, sugar, ghee, cotton, plastic, common salt, copper, LPG, vinegar. Answer

        Wohler, a German chemist synthesized the compound urea from an inorganic compound Ammonium cyanate. Since then, several organic compounds were found to contain carbon as the main element in them. Hence organic chemistry is also known as the chemistry of carbon compounds.

        You have studied about ionic bond in the earlier chapter. In this chapter we will learn about the covalent bond.

9.1 Hydrocarbons - the fundamental organic compounds:-

        All organic compounds contain hydrogen along with carbon. They are the fundamental organic compounds also known as “parent” compounds. These compounds are known as Hydrocarbons. Some organic compounds also contain oxygen, halogens and sometimes nitrogen and sulphur.

        Methane also called marsh gas is an organic compound with molecular formula CH4. In this compound carbon is bonded to four hydrogen atoms. The electronic configuration of carbon is (2, 4). While the electronic configuration of hydrogen is 1. Carbon has four electrons in its outermost orbit and hence it is tetravalent.

        If carbon gets four electrons in the second orbit, its outermost orbit will be completely filled and will make it stable to attain the nearest inert gas configuration [Neon, (2.8)]. Carbon gets these four electrons by sharing one electron each with each hydrogen atom. In the process, four C - H bonds are formed. Bonds formed by sharing of electrons are known as covalent bonds. A single covalent bond is formed by sharing of two electrons. The structure of methane is

        In the structure, you can observe that carbon atom is centrally placed. If the electrons of carbon are shown by “X” and the electrons of hydrogen by a “.”, then the structure of methane will look like this:

Additional Resources :

Some more diagrams showing methane structure:

 


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