Question 1

Which of the following best describes the lattice energy of an ionic compound?

Accepted Answer

The energy required to completely separate a mole of a solid ionic compound into its gaseous ions.

Question 2

Which equation correctly represents Coulomb’s law for the electrostatic energy between two ions?

Accepted Answer

$$E_{el} = \kappa \frac{Q_1$ Q_2$}{d}$$

Question 3

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

Accepted Answer

All elements must always obey the octet rule.

Question 4

Which of the following molecules is an example of an exception to the octet rule due to having less than an octet?

Accepted Answer

BF$$_3$$

Question 5

What is the formal charge on the central nitrogen atom in the nitrate ion ($$NO_3$$^-$$) if the Lewis structure has one double bond and two single bonds to oxygen?

Accepted Answer

0

Question 6

Which of the following best explains why the reaction between sodium metal and chlorine gas to form sodium chloride is so exothermic?

Accepted Answer

The large lattice energy released when Na$$^+$$ and Cl$$^-$$ ions come together in the solid.

Question 7

Which of the following molecules has a trigonal planar electron-domain geometry according to VSEPR theory?

Accepted Answer

BF$$_3$$

Question 8

Which of the following statements about bond enthalpy is correct?

Accepted Answer

Bond enthalpy is the energy required to break one mole of a specific bond in the gas phase.

Question 9

Given the following bond enthalpies: $$D(C-H) = 415 kJ/$$mol, $$D(Cl-Cl) = 243 kJ/$$mol, $$D(C-Cl) = 328 kJ/$$mol, $$D(H-Cl) = 431 kJ/$$mol. Calculate $$\Delta H_{rxn}$$ for the reaction: $$CH_4(g$$) + $$Cl_2(g$$) \rightarrow CH_3Cl(g) + HCl(g)$$.

Accepted Answer

$$\Delta H_{rxn} = [415 + 243] - [328 + 431] = 658 - 759 = -101 kJ$$

Question 10

Which of the following molecules is nonpolar despite having polar bonds?

Accepted Answer

CO$$_2$$

Question 11

Which of the following best describes a coordinate covalent bond?

Accepted Answer

A covalent bond in which both electrons come from the same atom.

Question 12

Which of the following factors increases the lattice energy of an ionic compound?

Accepted Answer

Increasing the charge on the ions.

Question 13

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

Accepted Answer

$$C \equiv C \u003e C = C \u003e C - C$$

Question 14

Which of the following molecules has a molecular geometry described as 'bent' according to VSEPR theory?

Accepted Answer

H$$_2O$$

Question 15

Which of the following statements about resonance structures is TRUE?

Accepted Answer

Resonance structures represent different possible arrangements of electrons, not atoms.

Question 16

Which of the following best describes the dipole moment ($$\mu) of a $$molecule?

Accepted Answer

$$\mu = Qr$$, where $$Q is $$the magnitude of charge and $$r is $$the distance separating the charges.

Question 17

Which of the following molecules is expected to have the largest bond angle?

Accepted Answer

BF$$_3$$

Question 18

Which of the following is a correct statement about the effect of lone pairs on molecular geometry?

Accepted Answer

Lone pairs exert greater repulsive forces than bonding pairs, decreasing bond angles.

Question 19

Which of the following molecules is an example of a molecule with an expanded octet?

Accepted Answer

SF$$_6$$

Question 20

Which of the following best describes the difference between electron-domain geometry and molecular geometry?

Accepted Answer

Electron-domain geometry considers all electron domains, while molecular geometry considers only the arrangement of atoms.

Basic Concepts of Chemical Bonding: Ionic, Covalent, and Molecular Geometry

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