Q: Arrange the following ions in order of increasing ionic radius: $\mathrm{Br^{-}}$, $\mathrm{K^{+}}$, $\mathrm{Rb^{+}}$, $\mathrm{Se^{2-}}$.

$\mathrm{K^{+}} < \mathrm{Rb^{+}} < \mathrm{Br^{-}} < \mathrm{Se^{2-}}$

Q: Which statement best explains why $\mathrm{O^{2-}}$ has a larger radius than $\mathrm{F^{-}}$ in an isoelectronic series?

$\mathrm{O^{2-}}$ has fewer protons, so the electrons are held less tightly.

Q: A patient is found to have high levels of $\mathrm{Na^{+}}$ and $\mathrm{Mg^{2+}}$ in their blood. Which ion will have a smaller ionic radius, and why?

$\mathrm{Mg^{2+}}$; it has more protons pulling on the same number of electrons.

Q: Which of the following best describes an isoelectronic series?

A group of atoms or ions with the same number of electrons

Q: Arrange the following ions in order of decreasing ionic radius: $\mathrm{N^{3-}}$, $\mathrm{O^{2-}}$, $\mathrm{F^{-}}$, $\mathrm{Na^{+}}$.

$\mathrm{N^{3-}} > \mathrm{O^{2-}} > \mathrm{F^{-}} > \mathrm{Na^{+}}$

Q: A student arranges the ions $\mathrm{F^{-}}$, $\mathrm{O^{2-}}$, $\mathrm{Ne}$, $\mathrm{Na^{+}}$ in order of increasing radius. Which is correct?

$\mathrm{Na^{+}} < \mathrm{Ne} < \mathrm{F^{-}} < \mathrm{O^{2-}}$

Q: If two ions are isoelectronic, what determines which has the larger radius?

The ion with the lower nuclear charge (fewer protons) will have the larger radius.

Question 1

Which of the following ions has the largest ionic radius in the isoelectronic series: $\mathrm{O^{2-}}$, $\mathrm{F^{-}}$, $\mathrm{Na^{+}}$, $\mathrm{Mg^{2+}}$?

Accepted Answer

$\mathrm{O^{2-}}$

Question 2

When ranking the ionic radii of isoelectronic ions, which factor is most important?

Accepted Answer

The number of protons in the nucleus

Question 3

Arrange the following ions in order of increasing ionic radius: $\mathrm{Br^{-}}$, $\mathrm{K^{+}}$, $\mathrm{Rb^{+}}$, $\mathrm{Se^{2-}}$.

Accepted Answer

$\mathrm{K^{+}} < \mathrm{Rb^{+}} < \mathrm{Br^{-}} < \mathrm{Se^{2-}}$

Question 4

Which statement best explains why $\mathrm{O^{2-}}$ has a larger radius than $\mathrm{F^{-}}$ in an isoelectronic series?

Accepted Answer

$\mathrm{O^{2-}}$ has fewer protons, so the electrons are held less tightly.

Question 5

Given the ions $\mathrm{Fe^{2+}}$, $\mathrm{Mn^{2+}}$, $\mathrm{Ni^{2+}}$, $\mathrm{Zn^{2+}}$, which has the smallest ionic radius?

Accepted Answer

$\mathrm{Zn^{2+}}$

Question 6

For an isoelectronic series, which ion will have the smallest radius?

Accepted Answer

The ion with the most protons

Question 7

A patient is found to have high levels of $\mathrm{Na^{+}}$ and $\mathrm{Mg^{2+}}$ in their blood. Which ion will have a smaller ionic radius, and why?

Accepted Answer

$\mathrm{Mg^{2+}}$; it has more protons pulling on the same number of electrons.

Question 8

Which of the following ions is isoelectronic with $\mathrm{Ne}$?

Accepted Answer

$\mathrm{F^{-}}$

Question 9

If you have the ions $\mathrm{Cl^{-}}$, $\mathrm{S^{2-}}$, $\mathrm{K^{+}}$, and $\mathrm{Ca^{2+}}$, which has the largest ionic radius?

Accepted Answer

$\mathrm{S^{2-}}$

Question 10

Which of the following best describes an isoelectronic series?

Accepted Answer

A group of atoms or ions with the same number of electrons

Question 11

Arrange the following ions in order of decreasing ionic radius: $\mathrm{N^{3-}}$, $\mathrm{O^{2-}}$, $\mathrm{F^{-}}$, $\mathrm{Na^{+}}$.

Accepted Answer

$\mathrm{N^{3-}} > \mathrm{O^{2-}} > \mathrm{F^{-}} > \mathrm{Na^{+}}$

Question 12

A chemist is comparing the ionic radii of $\mathrm{Al^{3+}}$ and $\mathrm{Na^{+}}$ in an isoelectronic series. Which is smaller and why?

Accepted Answer

$\mathrm{Al^{3+}}$; it has more protons attracting the same number of electrons.

Question 13

Which of the following ions would you expect to have the smallest ionic radius: $\mathrm{P^{3-}}$, $\mathrm{S^{2-}}$, $\mathrm{Cl^{-}}$, $\mathrm{K^{+}}$?

Accepted Answer

$\mathrm{K^{+}}$

Question 14

In a hospital setting, why is it important to know the relative sizes of ions such as $\mathrm{Na^{+}}$ and $\mathrm{K^{+}}$?

Accepted Answer

Their sizes affect how they move through cell membranes and influence nerve signaling.

Question 15

Which of the following ions is NOT isoelectronic with $\mathrm{Ar}$?

Accepted Answer

$\mathrm{S^{2-}}$

Question 16

A student arranges the ions $\mathrm{F^{-}}$, $\mathrm{O^{2-}}$, $\mathrm{Ne}$, $\mathrm{Na^{+}}$ in order of increasing radius. Which is correct?

Accepted Answer

$\mathrm{Na^{+}} < \mathrm{Ne} < \mathrm{F^{-}} < \mathrm{O^{2-}}$

Question 17

Which of the following ions has the greatest number of electrons?

Accepted Answer

$\mathrm{S^{2-}}$

Question 18

If two ions are isoelectronic, what determines which has the larger radius?

Accepted Answer

The ion with the lower nuclear charge (fewer protons) will have the larger radius.

Ranking Ionic Radii and Isoelectronic Species in GOB Chemistry

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