Q: A molecule has a central atom with three bonding pairs and one lone pair. What is the electron geometry and molecular geometry, respectively?

Tetrahedral, trigonal pyramidal

Q: Which of the following is the correct Lewis structure for the nitrate ion, $\mathrm{NO_3^-}$?

One N–O double bond and two N–O single bonds, with formal charges distributed to minimize the overall charge.

Q: Which of the following best explains why $\mathrm{H_2O}$ has a bent molecular geometry?

The central oxygen atom has two lone pairs, which repel the bonding pairs, resulting in a bent shape.

Q: Which of the following statements about bond energy and bond length is correct?

Triple bonds are shorter and stronger than double bonds.

Q: Which of the following is the correct order of steps to draw a Lewis structure for a polyatomic ion?

Count valence electrons, draw skeleton, assign electrons to bonds and lone pairs, check octet, assign formal charges.

Q: Which of the following best explains why $\mathrm{O_3}$ (ozone) has a bond order of 1.5?

The double bond is delocalized over two resonance structures, resulting in an average bond order.

Q: Which of the following statements about formal charge is correct?

Formal charge is calculated as: (valence electrons) - (nonbonding electrons) - 1/2(bonding electrons).

Q: Which of the following best describes the hybridization and geometry of the central atom in $\mathrm{XeF_4}$?

$sp^3d^2$ hybridization, square planar geometry

Q: Which of the following is the best explanation for why $\mathrm{CH_4}$ is nonpolar, even though it contains polar bonds?

The molecular geometry is tetrahedral, causing the bond dipoles to cancel out.

Question 1

Which of the following statements best describes the purpose of the VSEPR model in molecular geometry?

Accepted Answer

It determines the three-dimensional geometry of molecules by minimizing electron pair repulsions around a central atom.

Question 2

Given the Lewis structure of $\mathrm{CO_2}$, what is the hybridization of the central carbon atom?

Accepted Answer

$sp$

Question 3

Which of the following molecules is expected to have a net dipole moment?

Accepted Answer

$\mathrm{NH_3}$

Question 4

Which of the following correctly ranks the atoms F, O, and N in order of increasing electronegativity?

Accepted Answer

N < O < F

Question 5

A molecule has a central atom with three bonding pairs and one lone pair. What is the electron geometry and molecular geometry, respectively?

Accepted Answer

Tetrahedral, trigonal pyramidal

Question 6

Which of the following is the correct Lewis structure for the nitrate ion, $\mathrm{NO_3^-}$?

Accepted Answer

One N–O double bond and two N–O single bonds, with formal charges distributed to minimize the overall charge.

Question 7

Which of the following best explains why $\mathrm{H_2O}$ has a bent molecular geometry?

Accepted Answer

The central oxygen atom has two lone pairs, which repel the bonding pairs, resulting in a bent shape.

Question 8

Which of the following statements about bond energy and bond length is correct?

Accepted Answer

Triple bonds are shorter and stronger than double bonds.

Question 9

What is the formal charge on the central atom in the Lewis structure of $\mathrm{NH_4^+}$?

Accepted Answer

0

Question 10

Which of the following best describes the hybridization of the central atom in $\mathrm{SF_6}$?

Accepted Answer

$sp^3d^2$

Question 11

A chemist wants to determine the $\Delta H$ for the reaction $\mathrm{H_2(g) + Cl_2(g) \rightarrow 2HCl(g)}$. Given the following bond energies: $\mathrm{H-H}$: 436 kJ/mol, $\mathrm{Cl-Cl}$: 243 kJ/mol, $\mathrm{H-Cl}$: 431 kJ/mol, what is $\Delta H$ for the reaction?

Accepted Answer

$-184$ kJ/mol

Question 12

Which of the following molecules or ions has a central atom with $sp^2$ hybridization?

Accepted Answer

$\mathrm{BF_3}$

Question 13

Which of the following is the correct order of steps to draw a Lewis structure for a polyatomic ion?

Accepted Answer

Count valence electrons, draw skeleton, assign electrons to bonds and lone pairs, check octet, assign formal charges.

Question 14

Which of the following best explains why $\mathrm{O_3}$ (ozone) has a bond order of 1.5?

Accepted Answer

The double bond is delocalized over two resonance structures, resulting in an average bond order.

Question 15

Which of the following is the correct electron geometry for $\mathrm{PCl_5}$?

Accepted Answer

Trigonal bipyramidal

Question 16

A molecule has a central atom with two lone pairs and two bonding pairs. What is the molecular geometry?

Accepted Answer

Bent

Question 17

Which of the following statements about formal charge is correct?

Accepted Answer

Formal charge is calculated as: (valence electrons) - (nonbonding electrons) - 1/2(bonding electrons).

Question 18

Which of the following molecules has a bond angle closest to $120^\circ$?

Accepted Answer

$\mathrm{BF_3}$

Question 19

Which of the following best describes the hybridization and geometry of the central atom in $\mathrm{XeF_4}$?

Accepted Answer

$sp^3d^2$ hybridization, square planar geometry

Question 20

Which of the following is the best explanation for why $\mathrm{CH_4}$ is nonpolar, even though it contains polar bonds?

Accepted Answer

The molecular geometry is tetrahedral, causing the bond dipoles to cancel out.

Chemical Bonding, Molecular Geometry, and Lewis Structures: Study Notes

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