Chemistry NCERT Exemplar Solutions Class 11th Chapter Three

This is a Short Answer Type Questions as classified in NCERT Exemplar

This is a Short Answer Type Questions as classified in NCERT Exemplar

Transition elements are named so because they form a bridge between s-block elements and p-block elements. Zn, Cd and Hg are among those elements that are dblock elements but they do not exhibit most of the properties of transition elements.

This is a Short Answer Type Questions as classified in NCERT Exemplar

As the atomic size of F is much smaller which leads to high e^- - e ^- repulsion upon addition of electrons thus its electron gain enthalpy is less than that of Cl.

This is a Long Answer Type Questions as classified in NCERT Exemplar

Ans: As we move across the periodic table the ionization energy increases because of the increase in the effective nuclear charge and decrease of the shielding effect as more and more electrons get added in the same orbital.

Thus group 1 has lower ionization enthalpy compared to that of group 17 and also group 1 by losing one electron it will acquire the nearest noble gas electronic configuration which also contributes towards its lower ionization enthalpy.

This is a Long Answer Type Questions as classified in NCERT Exemplar

The following points make long form of periodic table better than Mendeleev's periodic table :-

(a) It is a periodic function of atomic number

(b) Elements are grouped as per there outermost electronic configuration

(c) Proper segregation of metals and non-metals

(d) More appropriate position of group VII.

This is a Long Answer Type Questions as classified in NCERT Exemplar

Mendeleev's arranged the elements as the periodicity of their atomic weights.

The drawbacks of Mendeleev's periodic table are as follows:-

(a) The position of hydrogen in the periodic table is not specified

(b) Isotopes are not included in the periodic table

(c) Elements with higher atomic mass are placed before the elements with lower atomic mass. For e.g- Co & Ni

(d) Gaps are left in his table considering the fact that more elements are yet to be discovered

(e) Inappropriate position of group VII.

This is a Long Answer Type Questions as classified in NCERT Exemplar

The group 1 elements are called alkali metals which possess outermost electronic configuration as ns1 .All the elements that have same outermost electron configuration possess similar properties and are placed in the same group.

This is a Long Type Questions as classified in NCERT Exemplar

The factors that affects electron gain enthalpy are as follows:

(a) Effective nuclear charge with its increase the electron gain enthalpy also increases

(b) Atomic size with its increase the electron gain enthalpy decreases

(c) The e-e - repulsion with its increase the electron gain enthalpy decreases

(d) Whenever there exists half filled or completely filled orbital than it lead to decrease the electron gain enthalpy because it leads to give extra stability to the atom due to symmetry

The electron gain enthalpy decreases down the group and increases across the period.