Question

The reactivity of an atom arises from

a. the average distance of the outermost electron shell from the nucleus.

b. the existence of unpaired electrons in the valence shell.

c. the sum of the potential energies of all the electron shells.

d. the potential energy of the valence shell.

Answer 1

The reactivity of an atom arises due to the presence of unpaired electrons in the valence shells. When the valence shells are complete, the atom is unreactive. However, when they are incomplete, they are chemically reactive.

Hence, the correct option is (b) the existence of unpaired electrons in the valence shells.

The reactivity of an atom arises from the existence of unpaired electrons in the valence shell.

The reactivity of an atom does not arise from the average distance of the outermost electron shell from the nucleus. The average distance of the outermost electron shell from the nucleus determines the electron's energy level and does not affect the reactivity of an atom. Hence, option ‘a’ is not the right option.

Potential energy is the energy possessed by matter due to its position or structure. The electrons in an atom also possess potential energy, and the amount of potential energy possessed by the electron depends on the electron shell where they are present. The sum of the potential energies of all the electron shells does not affect the reactivity of an atom. Hence, option ‘c’ is not the right option.

The outermost shell of an atom is called its valence shell. The electrons in the valence shell contain the maximum potential energy. However, the reactivity of an atom does not arise from the potential energy of the valence shell. Hence, option ‘d’ is not the right option.

Orbital refers to the actual three-dimensional space around the nucleus where electrons are present. s and p orbitals are the different types of orbitals in an atom. The reactivity of an atom does not arise from the energy difference between the s and p orbitals. Hence, option ‘e’ is not the right option.

The correct option is (b) the existence of unpaired electrons in the valence shells.