The correct order of increasing metallic character of Na, Be, P, Mg and Si is

Core Logic

(1) IUPAC naming for Z=107: 1 = un, 0 = nil, 7 = sept. Hence, Unnilseptium. (Correct) (2) Size comparison of isoelectronic / neighboring species: Cations are always smaller than their parent atoms (Mg²⁺ < Mg$Mg^{2+} < Mg$, Al³⁺ < Al$Al^{3+} < Al$). Among Mg$Mg$ and Al$Al$ (same period), atomic radius decreases left to right, so Mg > Al$Mg > Al$. Thus, Mg is the largest. Among the isoelectronic cations Mg²⁺$Mg^{2+}$ and Al³⁺$Al^{3+}$ (both 10 electrons), higher nuclear charge pulls electrons closer, so Al³⁺ < Mg²⁺$Al^{3+} < Mg^{2+}$. Therefore, the largest is Mg and the smallest is Al³⁺$Al^{3+}$. (Statement says Al and Mg²⁺$Mg^{2+}$, which is Incorrect). (3) Li and Mg are diagonally placed across the 2nd and 3rd periods and exhibit similar properties, known as a diagonal relationship. (Correct) (4) In [AlCl(H₂O)₅]²⁺$[AlCl(H_2O)_5]^{2+}$, the ligands are Cl^-$Cl^-$ (charge -1) and H₂O$H_2O$ (charge 0). x - 1 + 0 = +2 x = +3$x - 1 + 0 = +2 \implies x = +3$. The coordination number (covalency) is 1 + 5 = 6$1 + 5 = 6$. (Correct)

Step 1: Final Conclusion

Statement (2) is incorrect because Mg is the largest and Al³⁺$Al^{3+}$ is the smallest among the given species.

Pattern Recognition

Radius of Parent Atom > Radius of its Cation. In isoelectronic series, Radius ∝ 1/Z$\propto 1/Z$. Therefore, Al³⁺ (Z=13)$Al^{3+} (Z=13)$ is strictly smaller than Mg²⁺ (Z=12)$Mg^{2+} (Z=12)$.

Chapter Mix

Class 11 Chemistry: Classification of Elements and Periodicity in Properties Class 12 Chemistry: Coordination Compounds