Question 1

According to Mullins’ two fundamental rules of organic chemistry, which statement best describes the second rule?

Accepted Answer

Atoms strive to achieve a full outer shell of electrons, typically eight (octet rule).

Question 2

Given the molecule carbon dioxide ($$\mathrm{CO_2$}$$), which statement correctly describes its polarity?

Accepted Answer

The molecule is nonpolar because the dipoles cancel due to its linear geometry.

Question 3

Which of the following bonds is considered polar covalent based on Pauling electronegativity values?

Accepted Answer

The bond between hydrogen ($$\mathrm{H}$$, EN = 2.1) and chlorine ($$\mathrm{Cl}$$, EN = 3.0).

Question 4

What is the formal charge on the nitrogen atom in the ammonium ion ($$\mathrm{NH_4$^+}$$)?

Accepted Answer

+1

Question 5

Which VSEPR geometry is expected for a molecule with four electron groups (including lone pairs) around a central atom?

Accepted Answer

Tetrahedral

Question 6

Which hybridization is found in the central carbon atom of acetylene ($$\mathrm{C_2H_2}$$)?

Accepted Answer

$$\mathrm{sp}$$

Question 7

In ethene ($$\mathrm{C_2H_4}$$), how is the double bond between the two carbon atoms constructed?

Accepted Answer

One $$\sigma$$ bond from $$\mathrm{sp^2$}$$ hybrid orbitals and one $$\pi$$ bond from unhybridized $$\mathrm{p}$$ orbitals.

Question 8

Which of the following molecules has a net dipole moment?

Accepted Answer

Water ($$\mathrm{H_2O})$$

Question 9

Which statement about resonance structures is correct?

Accepted Answer

Resonance structures differ only in the placement of electrons, not atoms.

Question 10

Which orbital is involved in the formation of a $$\pi$$ bond in a double bond?

Accepted Answer

Unhybridized $$\mathrm{p}$$ orbital

Question 11

A molecule has the following Lewis structure: $$\mathrm{O=N^+=O^-}. $$What is the formal charge on the central nitrogen atom?

Accepted Answer

+1

Question 12

Which of the following is a valid resonance structure for the acetate ion ($$\mathrm{CH_3COO^-}$$)?

Accepted Answer

The negative charge is delocalized between the two oxygen atoms.

Question 13

Which hybridization corresponds to a trigonal planar geometry?

Accepted Answer

$$\mathrm{sp^2$}$$

Question 14

Which of the following best explains why the nitrate ion ($$\mathrm{NO_3$^-}) is $$more stable than its hypothetical single resonance form?

Accepted Answer

Delocalization of electrons lowers the energy of the molecule.

Question 15

Which molecule below contains an ionic bond?

Accepted Answer

Sodium chloride ($$\mathrm{NaCl})$$

Question 16

Which of the following is NOT a requirement for valid resonance structures?

Accepted Answer

The net charge must remain the same.

Question 17

Which molecular geometry is expected for ammonia ($$\mathrm{NH_3$}) $$according to VSEPR theory?

Accepted Answer

Trigonal pyramidal

Question 18

Which of the following statements about the construction of triple bonds is correct?

Accepted Answer

A triple bond consists of one $$\sigma$$ bond and two $$\pi$$ bonds.

Question 19

Which of the following best describes the difference between $$\sigma$$ and $$\pi$$ bonds?

Accepted Answer

$$\sigma$$ bonds are formed by head-on overlap of orbitals, while $$\pi$$ bonds are formed by side-on overlap of unhybridized $$\mathrm{p}$$ orbitals.

Question 20

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

Accepted Answer

Bent

Organic Chemistry Study Guide: Fundamentals, Bonding, and Structure (Ch. 1 & 2)

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