Chapter 6, Problem 2STP

Interpretation Introduction

Interpretation:

The incorrect statement from the given options needs to be selected.

Concept introduction:

Atomic size decrease on moving from left to right in a period. Electronegativity increases on moving from left to right in a period, the ionic radius of negatively charged ion is more than the atomic radius of the same atom and the ionization energy decreases down the group.

Answer to Problem 2STP

The incorrect statement is A.

Explanation of Solution

In the periodic table, the atomic size decrease from left to right. Sodium and Magnesium both belong to third period but sodium belongs to group I and magnesium belongs to group II, which means, sodium comes first on moving from left to right. So, atomic radius of Sodium is more than atomic radius of magnesium. So, statement A is incorrect.

Conclusion

Carbon (C) and Boron (B) both belong to third period but Carbon belongs to group 14 and boron belongs to group 13. On moving left to right in the periodic table, electro negativity increases. So, carbon is more electronegative than boron. So, option B is correct

The ionic radius of negatively charged ion is greater than the atomic radius of the same element. So, ionic radius of ${\text{Br}}^{-}$ is greater than atomic radius of $\text{Br}$. So, option B is correct.

Ionization energy decreases down the group and increase along a period. Potassium and Rubidium both belongs to Group I but Potassium is in 4^th period and Rubidium is in 5^th period. So, potassium has greater first ionization enthalpy than Rubidium. So, option D is correct.