Find the CBSE Class 11 Chemistry NCERT Solution for the Chapter- 4, Chemical Bonding and Molecular Structure. It has been framed keeping the Students' perspective in mind. This will help the Students with easy and simple understanding of the concept and technique employed in solving as per the CBSE Marking Scheme.
Few Sample Questions from this Chapter are given below:
Q. Explain the formation of a chemical bond.
Sol. A chemical bond is defined as an attractive force that holds the constituents (atoms, ions, etc.) together in a chemical species. Various theories have been suggested for the formation of chemical bonds such as the electronic theory, Valence shell electron pair repulsion theory, valence bond theory and molecular orbital theory. A chemical bond is attributed to the tendency of a system to attain stability. It was observed that the inertness of noble gases was because of their fully filled outermost orbitals. Hence, it was postulated that the elements having incomplete outermost shells are unstable (reactive). Atoms therefore, combine with each other and complete their octets or duplets to attain stable configuration of the nearest noble gases. This combination can occur either by sharing of electrons or by transferring one or more electrons from one atom to another. The chemical bond formed as a result of sharing of electrons between atoms is called covalent bond. An ionic bond is formed as a result of the transference of electrons from one atom to another.
Q. Explain with help of a suitable example polar covalent bond.
Sol. When two dissimilar atoms having different electronegativities combine to form a covalent bond, the bond pair of electrons is not shared equally. The bond pair shifts towards the nucleus of an atom having greater electronegativity. As a result electron distribution gets distorted and the electron cloud is displaced towards the electronegative atom.
As a result, the electronegative atom becomes slightly negatively charged while the other atom becomes slightly positively charged. Thus, opposite poles are developed in the molecule and this type of bond is called polar covalent bond.
HCl, for example contains a polar covalent bond. Chlorine atom is more electronegative than the hydrogen atom. Hence, the bond pair lies towards chlorine therefore, it acquires a partial negative charge.
Q. Write the significance of a plus and minus shown in representing the orbitals.
Sol. Molecular orbitals are represented by wave functions. A plus sign in an orbital represents positive wave function while a negative sign indicates a negative wave function.