Question 1

Which of the following statements best explains why cations are smaller than their corresponding neutral atoms?

Accepted Answer

Cations have fewer electrons, reducing electron–electron repulsion and often resulting in a lower principal quantum number for the valence shell.

Question 2

Which of the following ions has a noble-gas electron configuration?

Accepted Answer

Cl$$^{-}$$

Question 3

The first ionization energy of oxygen is lower than expected compared to other group 6A elements. Which explanation best accounts for this trend?

Accepted Answer

The first electron is removed from a filled orbital, resulting in increased electron–electron repulsion.

Question 4

Which of the following best describes the electron affinity of group 7A elements (halogens)?

Accepted Answer

Their electron affinity is negative, meaning energy is released when an electron is added.

Question 5

Which of the following statements about the octet rule is correct?

Accepted Answer

Main-group elements tend to react to achieve eight outer-shell electrons, attaining a noble-gas electron configuration.

Question 6

A sodium atom (Na) reacts with a chlorine atom (Cl) to form NaCl. Which process is most directly responsible for the formation of the ionic bond?

Accepted Answer

Sodium transfers its valence electron to chlorine, resulting in Na$$^{+}$$ and Cl$$^{-}$$ ions that are held together by electrostatic attraction.

Question 7

Which step in the Born-Haber cycle involves the energy required to convert a solid metal to gaseous atoms?

Accepted Answer

Sublimation energy

Question 8

Which of the following best describes lattice energy ($$U) in $$ionic solids?

Accepted Answer

The energy required to break up an ionic solid into individual gaseous ions.

Question 9

Which of the following elements is most likely to form a cation with a noble-gas electron configuration?

Accepted Answer

Potassium (K)

Question 10

Which of the following statements about ionic radii is correct?

Accepted Answer

Anions are larger than their neutral atoms because of additional electron–electron repulsions and decreased effective nuclear charge.

Question 11

Which of the following best explains why group 2A elements (Be, Mg, Ca) have slightly larger ionization energies than expected?

Accepted Answer

Their outermost electrons are removed from a filled s orbital, which is more stable.

Question 12

Which of the following is a correct electron configuration for the Mg$$^{2+}$$ ion?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$

Question 13

Which of the following best describes the trend in ionization energy across a period from left to right?

Accepted Answer

Ionization energy increases due to increased nuclear charge and decreased atomic radius.

Question 14

A student is asked to predict which compound has the higher lattice energy: NaCl or MgO. Which reasoning is correct?

Accepted Answer

MgO has a higher lattice energy because both ions have higher charges and smaller radii, increasing electrostatic attraction.

Question 15

Which of the following is the correct definition of ionization energy?

Accepted Answer

The energy required to remove the highest-energy electron from an isolated neutral atom in the gaseous state.

Question 16

Which of the following best explains why metals tend to lose electrons in chemical reactions?

Accepted Answer

Metals have low ionization energies and low electron affinities, making it energetically favorable to lose electrons.

Question 17

Which of the following is a multi-step process that can be used to calculate the lattice energy of an ionic solid?

Accepted Answer

Born-Haber cycle

Question 18

Which of the following ions does NOT have a true noble-gas electron configuration due to an additional filled d subshell?

Accepted Answer

Zn$$^{2+}$$

Question 19

Which of the following best describes the energy change when an electron is added to a group 2A element (alkaline earth)?

Accepted Answer

Energy is absorbed, and the electron affinity is approximately zero.

Question 20

A student is asked to explain why the second ionization energy of sodium is much higher than the first. Which explanation is correct?

Accepted Answer

The second electron is removed from a filled shell with a noble-gas configuration, requiring much more energy.

Ionic Compounds: Periodic Trends and Bonding Theory

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