Question

(a)At the equilibrium position when the distance between to ions? = ?0, the force of Coulombic attraction, ?? and the repulsive force ?? cancel each other, and the bond behaves like a spring. What is the important consequence of this behavior?

(b) What causes the repulsive force ?? ?

(c) Why is the radius of a ??1+-ion is less than that of ??-atom?

Answer 1

1. (a) At equilibrium as the force of columbic attraction and repulsive force cancel each other the bond length is maintained. The bond does not break as it behaves like a spring.

(b) As the atoms come closer the electron-electron interactions & nuclear –nuclear interactions between 2 atoms cause the repulsive force, F_R.

(c) Electronic configuration of sodium atom: Na – [Ne]1s¹.

Atomic number of sodium, Na is 11. Thus, it has 11 protons which pull the 11 electrons outside the nucleus. This is called the effective nuclear charge.

In case of Na⁺ ion, there are only 10 electrons outside the nucleus. Hence, the same pull of the protons are experienced by fewer number of electrons that is the effective nuclear charge on the electrons is increased. Hence because of relatively greater pull they are drawn more towards the nucleus, thereby having a smaller radius. Whereas in case of Na^-, the number of electrons are increased, hence the radius increases.