Question

The correct order of ionic radii of ions $Na^{+},Mg^{2 +},Al^{3 +}$ and $Si^{4 +}$ is

• A. $Na^{+} < Mg^{2 +} < Al^{3 +} < Si^{4 +}$
• B. $Mg^{2 +}>Na^{+}>Al^{3 +}>Si^{4 +}$
• C. $Al^{3 +}>Na^{+}>Si^{4 +}>Mg^{2 +}$
• D. $Na^{+}>Mg^{2 +}>Al^{3 +}>Si^{4 +}$

Answer 1

Answer: (D)

$Na^{+}>Mg^{2 +}>Al^{3 +}>Si^{4 +}$ . All are isoelectronic but nuclear charge per electron is greatest for $Si^{4 +}$ . So it has smallest size and nuclear charge per electron for $Na^{+}$ is smallest. So it has largest size.