Q: Which of the following is the correct formula for calculating the formal charge (FC) of an atom in a Lewis structure?

$FC = \#\,\text{valence electrons} - [\text{nonbonding electrons} + \frac{1}{2} \times \text{bonding electrons}]$

Q: A student is comparing the melting points of NaCl and MgO. Which statement best explains why MgO has a much higher melting point than NaCl?

MgO has ions with higher charges ($\text{Mg}^{2+}$ and $\text{O}^{2-}$) than NaCl ($\text{Na}^{+}$ and $\text{Cl}^{-}$), resulting in a much larger lattice energy

Question 1

Which of the following best explains why atoms form chemical bonds according to the Lewis model?

Accepted Answer

To lower the potential energy between the charged particles that compose atoms

Question 2

Which of the following statements about ionic bonds is correct?

Accepted Answer

Ionic bonds result from the attraction between cations and anions

Question 3

A pharmaceutical company is designing a drug to inhibit HIV-protease. Which aspect of bonding theory is most directly useful in simulating the shape of the drug molecule for this purpose?

Accepted Answer

Predicting the molecular geometry using Lewis structures

Question 4

Which of the following best describes the difference between covalent and metallic bonding?

Accepted Answer

Covalent bonding involves sharing of electrons between specific atoms, while metallic bonding involves delocalized electrons shared among all atoms

Question 5

Which of the following is the correct formula for calculating the formal charge (FC) of an atom in a Lewis structure?

Accepted Answer

$FC = \#\,	ext{valence electrons} - [	ext{nonbonding electrons} + \frac{1}{2} 	imes 	ext{bonding electrons}]$

Question 6

Which of the following trends is correct regarding lattice energy?

Accepted Answer

Lattice energy increases as the magnitude of the ionic charges increases

Question 7

A student is comparing the melting points of NaCl and MgO. Which statement best explains why MgO has a much higher melting point than NaCl?

Accepted Answer

MgO has ions with higher charges ($	ext{Mg}^{2+}$ and $	ext{O}^{2-}$) than NaCl ($	ext{Na}^{+}$ and $	ext{Cl}^{-}$), resulting in a much larger lattice energy

Question 8

Which of the following best describes a resonance structure?

Accepted Answer

A structure in which electrons are delocalized and more than one valid Lewis structure can be drawn differing only in the position of electrons

Question 9

Which of the following molecules is expected to have the shortest and strongest bond, based on the number of shared electrons?

Accepted Answer

$	ext{N}_2$ (triple bond)

Question 10

Which of the following statements about the properties of ionic compounds is FALSE?

Accepted Answer

Ionic compounds conduct electricity in the solid state

Question 11

Which of the following best explains why molecular compounds generally have lower melting points than ionic compounds?

Accepted Answer

Molecular compounds have weaker intermolecular forces compared to the strong electrostatic forces in ionic compounds

Question 12

Which of the following is the correct order of bond length for the following carbon-carbon bonds?

Accepted Answer

$	ext{C} \equiv 	ext{C} < 	ext{C} = 	ext{C} < 	ext{C} - 	ext{C}$

Question 13

Which of the following best describes the trend in electronegativity across the periodic table?

Accepted Answer

Electronegativity decreases down a group and increases across a period

Question 14

A bond between two atoms has an electronegativity difference of 1.5. According to the Lewis model, what type of bond is this?

Accepted Answer

Polar covalent

Question 15

Which of the following is a correct statement about the Born-Haber cycle?

Accepted Answer

It is a hypothetical series of steps used to determine the lattice energy of an ionic compound

Question 16

Which of the following is NOT a valid exception to the octet rule?

Accepted Answer

All noble gases forming compounds with less than eight electrons

Question 17

Which of the following best explains why ionic solids are brittle?

Accepted Answer

Because displacing ions in the lattice brings like charges next to each other, causing repulsion and shattering

Question 18

Which of the following statements about metallic bonding is correct?

Accepted Answer

Metallic bonding involves a 'sea' of delocalized electrons shared among all metal cations

Question 19

Which of the following best describes the relationship between bond energy and bond length for covalent bonds between like atoms?

Accepted Answer

As bond length increases, bond energy decreases

Question 20

A molecule of $	ext{CO}_2$ is found to have two resonance structures. What does this imply about the actual structure of $	ext{CO}_2$?

Accepted Answer

The actual structure is a resonance hybrid, with electrons delocalized over the molecule

Chapter 9: Chemical Bonding I – The Lewis Model

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