Given below are two statements : Statement (I): The first ionisation enthalpy of group 14 elements is higher than the corresponding elements of group 13. Statement (II) : Melting points and boiling points of group 13 elements are in general much higher than those the corresponding elements of group 14. In the light of the above statements, choose the most appropriate answer from the options given below:

Core Logic

• Statement I is correct: Moving left-to-right across a period from Group 13 to Group 14 increases the effective nuclear charge (Zeff$Z_{\text{eff}}$) and decreases the atomic radius. Consequently, more energy is required to extract an electron, so Group 14 elements exhibit higher first ionisation enthalpies.
• Statement II is incorrect: Group 14 elements (like Carbon, Silicon, Germanium) build robust, highly stable three-dimensional covalent network crystal structures. As a result, the melting and boiling points of Group 14 elements are generally much higher than those of the corresponding Group 13 elements.

Pattern Recognition

Covalent network solids (Group 14) create huge upward steps in phase transition energy compared to Group 13 frameworks (e.g., Gallium, which melts at nearly room temperature).

Chapter Mix

Class 11 Chemistry: The p-Block Elements