List two reasons for carbon forming a large number of compounds. Name the type of bonding found in most of its compounds. Why does carbon form compounds mainly by this kind of bonding. Give reason why the carbon compounds : (i) Generally have low melting and boiling points. (ii) Do not conduct electricity in molten state.
Answers
1)
a) Catenation:
The tendency of an element to form chains of identical atoms is called catenation. This tendency is observed in the case of non-metals showing covalency of two or more. However, this property is maximum in carbon as it can combine with other carbon atoms by single, double or triple covalent bonds. The bonding can be extended to form long open chain (straight or branched) or closed ones. Catenation property depends upon the value of bond energy which is maximum in the case of carbon.
b) Tendency to combine with other non-metals:
Carbon has the ability to form strong covalent bonds with many other atoms such as H, O, S, N,Cl, Br, I, etc. The C-C bond energy is approximately equals to the magnitude of bond energies between carbon and various other atoms.
2) Covalent bond are found mostly in its compound.
3) Because carbon has 4 electrons in its outermost shell (and because each covalent bond requires a donation of 1 electron, per atom, to the bond) carbon has exactly four bonds to make, and is only stable if all 4 of these bonds are used. This same rule applies to all of the atoms in the second row of the periodic table.
4)
a) Simple molecular substances consist of molecules in which the atoms are joined by strong covalent bonds. However, the molecules are held together by weak forces so these substances have low melting and boiling points. They do not conduct electricity.
b) Carbon compounds does not conduct electricity in molten state because carbon shares all electrons with different atoms so that no free electron is left.