Question

Identify the smallest ion among the following:

• A. ${\mathrm{Al}}^{3+}$
• B. ${\mathrm{Na}}^{+}$
• C. ${\mathrm{Ba}}^{2+}$
• D. ${\mathrm{Mg}}^{2+}$

Answer 1

The correct option is A

${\mathrm{Al}}^{3+}$

The explanation for the correct answer:

Option (A) ${\mathrm{Al}}^{3+}$

• The ions are charged atoms or molecules.
• Positively charged ions are called cations and the negatively charged ions are anions.
• As the nuclear charge on an ion increases, electrons are more strongly attracted, and thus the size decreases.
• The given ions are ${\mathrm{Na}}^{+}$,${\mathrm{Ba}}^{2+}$, ${\mathrm{Mg}}^{2+}$,and ${\mathrm{Al}}^{3+}$.
• Therefore, among the given ions ${\mathrm{Al}}^{3+}$ have the highest $+3$ charge.
• Hence, the size of ${\mathrm{Al}}^{3+}$ is the smallest.