Briefly explain why electronic configurations of lanthanoids are not known with certainty.

In the lanthanoids, 4f and 5d subshells are very close in energy. The outermost 6s-orbital remains filled with two electrons (6s2) . The electrons can easily jump from 4f to 5d or vice-versa. Further, irregularities in electronic configurations are also […]

What are lanthanoids? Explain the position of lanthanoids in the periodic table.

The series involving the filling of 4f-orbitals following lanthanum La (Z = 57) is called lanthanoid series. The elements present in this series are called lanthanoids. There are fourteen elements in this series starting with cerium, Ce(Z = 58) and […]

Explain the meaning of inner transition series.

i. The last electron in the f-block elements enters into (n-2) f-orbitals, i.e., inner to the penultimate energy level and they form a transition series within the transition series (d-block elements). Hence, the f-block elements are known as inner transition […]

What are f-block elements?

i. The elements in which the last electron enters into (n–2) f-orbital of the atoms are called f-block elements. ii. In these elements, the last electron enters in to the prepenultimate (n–2) shell (called antepenultimate). iii. The general valence electronic […]

State the characteristics of interstitial compounds.

Characteristics of interstitial compounds: i. The chemical properties of interstitial compounds are similar to those of the parent transition metal. ii. They are hard and lustrous. iii. They exhibit electrical and thermal conductivity. iv. They have melting points higher than […]

Define ionization enthalpy. Explain the trends observed in the ionization enthalpies of the d-block elements.

Definition of ionization enthalpy. Ionization enthalpy is defined as the amount of energy required to remove the outermost electron completely from a gaseous atom in its ground state. Explanation of ionization enthalpies of the d-block elements. i. The ionization enthalpies of […]

Why are Cr, Mo and W hard metals while Zn, Cd and Hg are not very hard metals?

i. The d-orbitals containing unpaired electrons may overlap to form covalent bonds which are responsible for the hardness. ii. As the number of unpaired electrons increases, the number of covalent bonds and the strength of the metallic bonds increases. The […]