Question 1

Which of the following best explains why alkali metals are strong reducing agents?

Accepted Answer

They have a single electron in their highest-energy $$ns^1$$ valence shell, which is easily lost.

Question 2

When a main-group metal forms a cation, which electrons are lost first?

Accepted Answer

Electrons from the highest-energy shell

Question 3

Which of the following ions is isoelectronic with neon ($$Ne$$)?

Accepted Answer

$$Na^+$$

Question 4

A neutral atom of sulfur ($$S) $$has the electron configuration $$[Ne]3s^2$ 3p^4$. What is the condensed electron configuration of the S$$^{2-}$$ ion?

Accepted Answer

$$[Ne]3s^2$ 3p^6$

Question 5

Which of the following statements about periodic trends in atomic radii is correct?

Accepted Answer

Atomic size increases down a group and decreases across a period.

Question 6

Why are cations smaller than their parent atoms?

Accepted Answer

Cations have fewer electrons, reducing electron shielding and increasing effective nuclear charge.

Question 7

Which of the following ions is the largest in size?

Accepted Answer

$$F^-$$

Question 8

When forming a cation, which subshell do transition metals lose electrons from first?

Accepted Answer

The highest-energy s-subshell

Question 9

Which of the following best describes the trend in ionic radii for anions compared to their parent atoms?

Accepted Answer

Anions are larger than their parent atoms due to increased electron-electron repulsion and decreased effective nuclear charge.

Question 10

Which of the following ions has the same electron configuration as argon ($$Ar$$)?

Accepted Answer

$$Cl^-$$

Question 11

A patient is given a medication containing $$Ca^{2+}$$ ions. Compared to a neutral calcium atom, the $$Ca^{2+}$$ ion:

Accepted Answer

Has fewer electrons and a smaller radius

Question 12

Which of the following correctly ranks the following isoelectronic species from largest to smallest radius: $$F^-$$, $$Na^+$$, $$Mg^{2+}$$?

Accepted Answer

$$F^- \u003e Na^+ \u003e Mg$$^{2+}$$

Question 13

Which of the following best explains why atomic size decreases across a period?

Accepted Answer

Effective nuclear charge increases, pulling electrons closer to the nucleus.

Question 14

Which of the following elements forms a cation by losing electrons from both the highest-energy p- and s-subshells?

Accepted Answer

Lead ($$Pb)$$

Question 15

A transition metal ion has the electron configuration $$[Ar]3d^5$. Which ion is it?

Accepted Answer

$$Mn^{2+}$$

Question 16

Which of the following statements about the formation of main-group nonmetal anions is correct?

Accepted Answer

They gain electrons until their highest-energy shell is filled, matching the nearest noble gas.

Question 17

Which of the following ions is expected to have the smallest radius?

Accepted Answer

$$Ca^{2+}$$

Question 18

Which of the following best describes the electron configuration of $$Sn^{4+}$$?

Accepted Answer

$$[Kr]5s^2$ 4d$$^{10}$$

Question 19

Which of the following is a correct statement about the periodic trend in ionic radii for cations and anions?

Accepted Answer

Cations are smaller than their parent atoms, while anions are larger than their parent atoms.

Question 20

A sample contains the ions $$Ar$$, $$Br^-$$, $$Ca^{2+}$$, and $$Kr. $$Which of the following correctly ranks them from largest to smallest radius?

Accepted Answer

$$Kr \u003e Br^- \u003e Ar \u003e Ca$$^{2+}$$

Electron Configurations of Ions and Periodic Trends

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