Question

(a) What do you mean by covalent bond?
(b) Write the electron dot structure of methane and ethene.
(c) Explain the following with example.
(i) Addition reaction.
(ii) Displacement reaction.

Answer 1

(a) A covalent bond, also called a molecular bond, is a chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs, and the stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding.
(b) As shown in the image.
(c)

(i) An addition reaction is an organic reaction in which two or more molecules recombine to form a larger molecule. The reaction only occurs between chemical compounds that have multiple bonds. In organic chemistry, the most common use of addition reactions involves alkenes. Addition of chlorine to ethylene is an example.
(ii) Displacement reaction is a chemical reaction in which a more reactive element displaces a less reactive element from its compound. Both metals and non-metals take part in displacement reactions. The reaction of iron nails with copper sulphate solution.