The effective nuclear charge ($$Z_{\text{eff}}) $$increases, pulling electrons closer to the nucleus.

Question 1

Which of the following best explains why ionization energy increases across a period in the periodic table?

Accepted Answer

The effective nuclear charge ($$Z_{	ext{eff}}) $$increases, pulling electrons closer to the nucleus.

Question 2

Which element has the largest first ionization energy ($$E_{i1}) in $$the periodic table?

Accepted Answer

Helium (He)

Question 3

Why do halogens have large, negative electron affinities?

Accepted Answer

Adding an electron to a halogen leads to an anion with a filled valence shell.

Question 4

Which of the following best describes the trend in atomic radii down a group?

Accepted Answer

Atomic radius increases due to the addition of electron shells.

Question 5

What is the driving force for the formation of an ionic compound such as NaCl?

Accepted Answer

The negative of the lattice energy, which is the energy released when gaseous ions coalesce to form an ionic solid.

Question 6

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

Accepted Answer

Na$$^+$$

Question 7

Which step in the Born-Haber cycle for NaCl formation is most energetically favorable?

Accepted Answer

Formation of solid NaCl from gaseous Na$$^+$$ and Cl$$^- ($$lattice energy)

Question 8

Which of the following statements about electron affinity is correct?

Accepted Answer

Halogens have large, negative electron affinities.

Question 9

What is the effect of ion size on lattice energy?

Accepted Answer

Larger ions lead to smaller lattice energies.

Question 10

Which equation correctly represents the first ionization energy process for magnesium?

Accepted Answer

$$\mathrm{Mg}(g) \rightarrow \mathrm{Mg}^+(g) + e^-$$

Question 11

Which of the following best explains the periodic trend in ionization energy down a group?

Accepted Answer

Ionization energy decreases due to increased separation between valence electrons and the nucleus.

Question 12

Which of the following is true about the octet rule?

Accepted Answer

Main-group elements react to achieve a filled valence shell of 8 electrons.

Question 13

Which of the following best describes the formation of an ionic bond?

Accepted Answer

Electrons are transferred from one atom to another.

Question 14

Which of the following factors increases the strength of an ionic bond?

Accepted Answer

Larger charges and smaller radii of the ions.

Question 15

Which of the following is the correct formula for estimating lattice energy?

Accepted Answer

$$	ext{Lattice energy} \propto \frac{(	ext{cation charge})(	ext{anion charge})}{	ext{cation radius} + 	ext{anion radius}}$$

Question 16

Which of the following statements about cations and anions is correct?

Accepted Answer

Cations are smaller and anions are larger than their parent atoms.

Question 17

Which of the following is a common exception to the solubility of sulfides in water?

Accepted Answer

Sulfides of group 1A cations and NH$$_4^+$$ are soluble.

Question 18

Which of the following best explains why the second ionization energy of phosphorus is much larger than the first?

Accepted Answer

The second ionization destroys a filled valence shell, requiring much more energy.

Question 19

Which of the following is true about the solubility of ionic compounds in water?

Accepted Answer

Ionic compounds with large ions and small charges are more soluble.

Periodic Trends, Ionic Bonds, and Lattice Energy: Study Notes for General Chemistry

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