Organic Chemistry Final Exam Lewis
Structures, Stereochemistry &
Intermolecular Forces (With
Rationales)&
Multiple Choice
Organic Chemistry Revision Guide – Lewis Structures, Stereochemistry & Intermolecular
Forces (With Rationales)
1. Best Statements About Lewis Dot Structures of Organic Molecules
Answer:
• The total number of electrons in the structure must equal the total number of valence
electrons of all atoms.
• Formal charge = Valence electrons − (Bonding electrons ÷ 2) − Nonbonding electrons.
Rationale: A correct Lewis structure must account for all valence electrons and minimize
formal charges whenever possible.
2. Lewis Dot Structure: Correct Number of Valence Electrons
Xe = 8 valence electrons
Rationale: Xenon is in Group 18 (noble gases), which have 8 valence electrons.
F = 7 valence electrons
Rationale: Fluorine is in Group 17 (halogens).
N = 5 valence electrons
Rationale: Nitrogen belongs to Group 15.
C = 4 valence electrons
Rationale: Carbon belongs to Group 14 and forms four covalent bonds.
, 3. Arsenic (As)
Answer: Group 15 → 5 valence electrons
Rationale: Elements in Group 15 all possess five valence electrons.
Amine Nomenclature
4. Primary Amine
Answer: Nitrogen attached to one carbon group and two hydrogens
Rationale: A primary amine contains one alkyl group attached to nitrogen.
5. Secondary Amine
Answer: Nitrogen attached to two carbon groups and one hydrogen
Rationale: Two alkyl groups replace two hydrogens.
6. Tertiary Amine
Answer: Nitrogen attached to three carbon groups
Rationale: No hydrogens remain attached to nitrogen.
7. Quaternary Ammonium Ion
Answer: Nitrogen attached to four carbon groups
Rationale: Nitrogen carries a positive charge because it forms four bonds.
Alkane Properties
8. Alkanes are soluble in nonpolar solvents and insoluble in water
Answer: True
Structures, Stereochemistry &
Intermolecular Forces (With
Rationales)&
Multiple Choice
Organic Chemistry Revision Guide – Lewis Structures, Stereochemistry & Intermolecular
Forces (With Rationales)
1. Best Statements About Lewis Dot Structures of Organic Molecules
Answer:
• The total number of electrons in the structure must equal the total number of valence
electrons of all atoms.
• Formal charge = Valence electrons − (Bonding electrons ÷ 2) − Nonbonding electrons.
Rationale: A correct Lewis structure must account for all valence electrons and minimize
formal charges whenever possible.
2. Lewis Dot Structure: Correct Number of Valence Electrons
Xe = 8 valence electrons
Rationale: Xenon is in Group 18 (noble gases), which have 8 valence electrons.
F = 7 valence electrons
Rationale: Fluorine is in Group 17 (halogens).
N = 5 valence electrons
Rationale: Nitrogen belongs to Group 15.
C = 4 valence electrons
Rationale: Carbon belongs to Group 14 and forms four covalent bonds.
, 3. Arsenic (As)
Answer: Group 15 → 5 valence electrons
Rationale: Elements in Group 15 all possess five valence electrons.
Amine Nomenclature
4. Primary Amine
Answer: Nitrogen attached to one carbon group and two hydrogens
Rationale: A primary amine contains one alkyl group attached to nitrogen.
5. Secondary Amine
Answer: Nitrogen attached to two carbon groups and one hydrogen
Rationale: Two alkyl groups replace two hydrogens.
6. Tertiary Amine
Answer: Nitrogen attached to three carbon groups
Rationale: No hydrogens remain attached to nitrogen.
7. Quaternary Ammonium Ion
Answer: Nitrogen attached to four carbon groups
Rationale: Nitrogen carries a positive charge because it forms four bonds.
Alkane Properties
8. Alkanes are soluble in nonpolar solvents and insoluble in water
Answer: True
