AP Chemistry — Unit 2: Molecular and Ionic Compound Structure and Properties

What AP Chemistry Unit 2 covers

The College Board Course and Exam Description breaks Unit 2 into 7 topics:

1. 2.1 Types of Chemical Bonds
2. 2.2 Intramolecular Force and Potential Energy
3. 2.3 Structure of Ionic Solids
4. 2.4 Structure of Metals and Alloys
5. 2.5 Lewis Diagrams
6. 2.6 Resonance and Formal Charge
7. 2.7 VSEPR and Bond Hybridization

AP Chemistry Unit 2 practice questions

• Electronegativity increases left → right across a period. What causes this trend?

  Rising nuclear charge with little added shielding pulls electrons harder. That rising effective pull raises electronegativity across a period.

• What defines a polar covalent bond?

  A bond where atoms of differing electronegativity share electrons unequally. The unequal sharing creates partial charges (δ+ and δ−).

• Electronegativity difference alone doesn't always determine bond type. What additional factor matters?

  Whether the bonding atoms are metals or nonmetals. Metal–nonmetal combinations are generally ionic; nonmetal–nonmetal combinations are generally covalent regardless of the electronegativity difference.

• What is the defining feature of metallic bonding at the particulate level?

  Delocalized valence electrons form a 'sea' of electrons around metal cations. No electron belongs to one atom; this explains conductivity and malleability.

• On a potential energy vs. internuclear distance graph for a diatomic molecule, what does the lowest point of the curve represent?

  Equilibrium bond length, where potential energy is lowest. It's the most stable internuclear distance.

• A C≡C triple bond is shorter and stronger than a C=C double bond. What causes this?

  Higher bond order packs more shared electron density, pulling nuclei closer. That makes the bond shorter and stronger.

• How does Coulomb's law describe the strength of attraction between a cation and anion?

  Force ∝ (q₁ × q₂)/r² — attraction grows with larger ion charges and shrinks with distance. Bigger charges and smaller ionic radii both strengthen the ionic bond.

• MgO has a much higher melting point than NaF. Both are ionic solids. What explains the difference?

  Mg²⁺ and O²⁻ (2± charges) attract about four times more strongly than Na⁺ and F⁻ (±1). Stronger Coulombic attraction means a higher melting point.

+ 22 more AP Chemistry cards in the app.

Key terms in Unit 2

These 12 terms show up in the Unit 2 cards. Each one links to its definition in the AP Chemistry key-term reference.

• Coulomb's law
• Covalent bond
• Dipole moment
• Electronegativity
• Formal charge
• Hybridization
• Interstitial alloy
• Lewis diagram
• Molecular geometry
• Polar covalent bond
• Substitutional alloy
• Valence electrons