Question

The ionic radius of ${\mathrm{Na}}^{+}$ ion is $1.02\stackrel{\circ }{\mathrm{A}}$. The ionic radii (in $\stackrel{\circ }{\mathrm{A}}$) of ${\mathrm{Mg}}^{2+}$ and ${\mathrm{Al}}^{3+}$, respectively are:

• A. $0.72\mathrm{and}0.54$
• B. $0.68\mathrm{and}0.72$
• C. $1.05\mathrm{and}0.99$
• D. $0.85\mathrm{and}0.99$

Answer 1

The correct option is A

$0.72\mathrm{and}0.54$

The correct options are (a)

The explanation for the correct options:

(a)

• Explanation: As the nucleus charge increases, the ionic radius of isoelectronic ions of the same period decreases. Isoelectronic means that two or more molecular entities have the same number of valence electrons and the same structure.
  Ionic size: $0.72\mathrm{and}0.54$
• As a result, option (a) is correct.

The explanation for the incorrect options:

(b)

• Explanation: The ionic radius of isoelectronic ions from the same period grew as the nucleus charge decreased. Isoelectronic means that two or more molecular entities have the same number of valence electrons and the same structure.
• As a result, option (b) is incorrect.

(c)

• Explanation: The ionic radius of isoelectronic ions of the same period increased as the nucleus increased in size. The charge was reduced. Isoelectronic means that two or more molecular entities have the same number of valence electrons and the same structure.
• As a result, option (c) is incorrect.

(d)

• Explanation: In isoelectronic ions of the same period, ionic radius increased as nucleus charge decreased. Isoelectronic means that two or more molecular entities have the same number of valence electrons and the same structure.
• As a result, option (d) is incorrect.

The correct answers are (a): The ionic radius of isoelectronic ions of the same period decreases due to increased nucleus charge.