Question 1

Which of the following statements best describes a sigma ($$\sigma) $$bond?

Accepted Answer

A bond formed by the end-to-end (head-on) overlap of orbitals along the bond axis.

Question 2

In the glycine molecule, what is the geometry around the central nitrogen atom (N)?

Accepted Answer

Trigonal pyramidal

Question 3

Which of the following bonds is expected to have the highest bond energy?

Accepted Answer

$$\mathrm{C\equiv C}$$

Question 4

What is the relationship between bond order and bond length?

Accepted Answer

As bond order increases, bond length decreases.

Question 5

Which of the following best explains why a triple bond is stronger than a single bond?

Accepted Answer

Triple bonds have more electrons shared, resulting in greater orbital overlap and higher bond energy.

Question 6

Given the following bond energies: $$\mathrm{C-H} (414 kJ/$$mol), $$\mathrm{O=O} (498 kJ/$$mol), $$\mathrm{C=O} (799 kJ/$$mol in CO$$_2$$), calculate the approximate energy required to convert methane ($$\mathrm{CH_4$}) $$and oxygen ($$\mathrm{O_2$}) to $$carbon dioxide ($$\mathrm{CO_2$}) $$and water ($$\mathrm{H_2O}) in $$the reaction: $$\mathrm{CH_4$ + 2O_2 \rightarrow CO_2$ + 2H_2O}.$$

Accepted Answer

$$-572 kJ/$$mol

Question 7

Which of the following bonds is the longest?

Accepted Answer

$$\mathrm{H-I}$$

Question 8

A molecule contains a double bond between two carbon atoms. How many sigma ($$\sigma) $$and pi ($$\pi) $$bonds are present in this double bond?

Accepted Answer

1 $$\sigma$$ bond and 1 $$\pi$$ bond

Question 9

Which of the following best describes the orientation of a pi ($$\pi) $$bond?

Accepted Answer

It is formed by the side-to-side overlap of p orbitals above and below the bond axis.

Question 10

Which of the following statements about bond energy is correct?

Accepted Answer

Bond energy is the amount of energy required to break a bond.

Question 11

Which of the following molecules contains both sigma and pi bonds?

Accepted Answer

$$\mathrm{C_2H_4} ($$ethylene)

Question 12

If the bond length of $$\mathrm{C\equiv C} is 120 pm $$and that of $$\mathrm{C-C} is 154 pm$$, what can you infer about the bond order and bond strength?

Accepted Answer

Higher bond order corresponds to shorter bond length and stronger bond.

Question 13

Which of the following best explains why $$\mathrm{H-F}$$ has a higher bond energy than $$\mathrm{H-I}$$?

Accepted Answer

$$\mathrm{H-F}$$ has a shorter bond length, resulting in stronger orbital overlap.

Question 14

Which of the following is true about the geometry around the central carbon atom in the carboxyl group ($$\mathrm{COOH}) of $$glycine?

Accepted Answer

It is trigonal planar due to the presence of a double bond and two single bonds.

Question 15

Which of the following best describes the difference between the shorthand and expanded Lewis structures for molecules like glycine?

Accepted Answer

Shorthand structures collapse hydrogens onto the atom they are bound to and often omit lone pairs.

Question 16

Which of the following is NOT a factor that dictates bond strength?

Accepted Answer

Number of lone pairs on adjacent atoms

Question 17

Which of the following best describes the bond in $$\mathrm{N_2$} ($$nitrogen gas)?

Accepted Answer

A triple bond with one sigma and two pi bonds

Question 18

Which of the following is the correct order of bond energies from lowest to highest for the following bonds: $$\mathrm{C-C}$$, $$\mathrm{C=C}$$, $$\mathrm{C\equiv C}$$?

Accepted Answer

$$\mathrm{C-C} \u003c \mathrm{C=C} \u003c \mathrm{C\equiv C}$$

Bonding in Molecules:Lecture 16

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