Q: Which equation correctly represents the relationship for lattice energy strength?

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

Q: Order LiCl, KCl, and KBr according to their expected lattice energies from greatest to least.

LiCl $$E_{\text{lattice}}$$ \u003e KCl $$E_{\text{lattice}}$$ \u003e KBr $$E_{\text{lattice}}$$

Question 1

Which of the following statements best explains why the first ionization energy of magnesium (Mg) is higher than that of aluminum (Al)?

Accepted Answer

Magnesium's 3s electrons are more tightly held than aluminum's 3p electron due to lower subshell energy.

Question 2

Which element has the largest first ionization energy ($$E_{i1}) $$and which has the smallest, according to periodic trends?

Accepted Answer

He has the largest $$E_{i1}$$; Fr has the smallest $$E_{i1}$$

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, releasing energy.

Question 4

Which step in the formation of NaCl(s) from its elements is the most energetically favorable?

Accepted Answer

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

Question 5

Which equation correctly represents the relationship for lattice energy strength?

Accepted Answer

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

Question 6

Which of the following best describes the periodic trend in atomic radii?

Accepted Answer

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

Question 7

What is the main 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 form an ionic solid.

Question 8

Which of the following statements about electron affinity is correct?

Accepted Answer

Alkaline earth metals have electron affinities approximately equal to zero.

Question 9

Which of the following ions would you expect to have the largest ionic radius?

Accepted Answer

Cl$$^-$$

Question 10

Order LiCl, KCl, and KBr according to their expected lattice energies from greatest to least.

Accepted Answer

LiCl $$E_{	ext{lattice}}$$ \u003e KCl $$E_{	ext{lattice}}$$ \u003e KBr $$E_{	ext{lattice}}$$

Question 11

Which of the following best explains why the second ionization energy ($$E_{i2}) of $$sodium is much larger than its first ionization energy ($$E_{i1}$$)?

Accepted Answer

The second ionization removes an electron from a filled valence shell.

Question 12

Which of the following is a consequence of Hund’s rule as it relates to ionization energy irregularities?

Accepted Answer

Removing a paired electron is easier than removing an unpaired electron from the same subshell.

Question 13

Which of the following best describes the relationship between lattice energy and ionic bond strength?

Accepted Answer

Lattice energy and ionic bond strength are directly proportional.

Question 14

A soluble ionic compound is most likely to contain which type of ions?

Accepted Answer

Large cations and large anions with small charges.

Question 15

Calculate the lattice energy for KCl given the following data: Heat of sublimation for K = 89.2 kJ/mol, bond dissociation energy for Cl$$_2 = 243 kJ/$$mol, $$E_{i1}$$ for K = 418.8 kJ/mol, $$E_{ea}$$ for Cl = -348.6 kJ/mol, net energy change for formation of KCl = -434.1 kJ/mol.

Accepted Answer

-837 kJ/mol

Question 16

Which of the following best describes the octet rule?

Accepted Answer

Main-group elements react to attain a filled valence shell with 8 valence electrons.

Question 17

Which of the following is true about the electron affinity of noble gases?

Accepted Answer

Noble gases have positive electron affinities because adding an electron destroys a filled valence shell.

Question 18

Which of the following best explains why cations are smaller than their parent atoms?

Accepted Answer

Cations lose electrons, reducing electron-electron repulsion and allowing the nucleus to pull remaining electrons closer.

Question 19

Which of the following is a correct real-world application of lattice energy?

Accepted Answer

Lattice energy determines the solubility of ionic compounds in water.

Periodic Trends, Ionization Energy, Electron Affinity, and Ionic Bonding

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