AP Classroom (Chemistry Unit 2, Ch. 7: Molecular and Ionic Compound Structure and Properties)

(Lewis Diagram C6H6) The diagram above shows two resonance structures for a molecule of C6H6. The phenomenon shown in the diagram best supports which of the following claims about the bonding in C6H6 ? A. In the C6H6C6H6 molecule, all the bonds between the carbon atoms have the same length. B. Because of variable bonding between its carbon atoms, C6H6C6H6 is a good conductor of electricity. C. The bonds between carbon atoms in C6H6C6H6 are unstable, and the compound decomposes quickly. D. The C6H6C6H6 molecule contains three single bonds between carbon atoms and three double bonds between carbon atoms.

A. In the C6H6C6H6 molecule, all the bonds between the carbon atoms have the same length.

(Lewis Diagram Nitrate Ion) Which of the following statements, if true, would support the claim that the NO3− ion, represented above, has three resonance structures? A. The NO3−NO3− ion is not a polar species. B. The oxygen-to-nitrogen-to-oxygen bond angles are 90°90°. C. One of the bonds in NO3−NO3− is longer than the other two. D. One of the bonds in NO3−NO3− is shorter than the other two.

A. The NO3−NO3− ion is not a polar species.

(Density) The particle-level diagram above represents the structure of solid KF. Although the molar mass of KCl is greater than that of KF, the density of KCl is actually less than that of KF. Which of the following representations of the structure of KCl best helps to explain this phenomenon?

A. smaller grey + circles, larger white - circles, evenly spaced out

(Lewis Diagram N2O) Which of the following Lewis diagrams best represents the bonding in the N2O molecule, considering formal charges?

B. (one lone pair) N///N-O (3 lone pairs)

(Steel) Steel is an alloy containing Fe atoms and C atoms. Which of the following diagrams best represents the particle-level structure of steel?

B. Fe = large white circle, C = small grey circle, C in spaces b/n Fe

(Compound of C and Se) The elements C and Se have the same electronegativity value, 2.55. Which of the following claims about the compound that forms from C and Se is most likely to be true? A. The carbon-to-selenium bond is unstable. B. The carbon-to-selenium bond is nonpolar covalent. C. The compound has the empirical formula CSeCSe. D. A molecule of the compound will have a partial negative charge on the carbon atom.

B. The carbon-to-selenium bond is nonpolar covalent.

(Molecular Geometry) In the following diagrams, elements are represented by X and Z, which form molecular compounds with one another. Which diagram represents a molecule that has a bent molecular geometry?

B. Z-X-Z (two lone pairs on X)

(Alloy) Copper atoms and zinc atoms have the same atomic radius, 135 picometers. Based on this information, which of the following diagrams best represents an alloy containing only copper and zinc atoms?

B. same sized white and grey circles evenly spaced out

(Compound of Alkali Metal and Halogen) Two pure elements react to form a compound. One element is an alkali metal, X, and the other element is a halogen, Z. Which of the following is the most valid scientific claim that can be made about the compound? A. It has the formula XZ2XZ2. B. It does not dissolve in water. C. It contains ionic bonds. D. It contains covalent bonds.

C. It contains ionic bonds.

(Conductivity of Compound) Which of the following correctly indicates whether the solid represented by the particulate model shown above conducts electricity and explains why or why not? A. It conducts electricity because it is made of positive and negative ions. B. It conducts electricity because it is made of particles of different sizes. C. It does not conduct electricity because its ions cannot move freely within the solid. D. It does not conduct electricity because there are small spaces between the particles.

C. It does not conduct electricity because its ions cannot move freely within the solid.

(Bonding in Metals) A particle-level diagram of a metallic element is shown above. Typically, metals are both malleable and ductile. The best explanation for these properties is that the electrons involved in bonding among metal atoms are A. unequally shared and form nondirectional bonds B. unequally shared and form highly directional bonds C. equally shared and form nondirectional bonds D. equally shared and form highly directional bonds

C. equally shared and form nondirectional bonds

(Bond Angle) Which of the following complete Lewis diagrams represents a molecule containing a bond angle that is closest to 120°?

D. H O H-C-C-O-H H

(Bonding in HF) Which of the following scientific claims about the bond in the molecular compound HF is most likely to be true? A. There is a partial negative charge on the HH atom. B. Electrons are shared equally between the HH and FF atoms. C. The bond is extremely weak. D. The bond is highly polar.

D. The bond is highly polar.

(Lattice Energy) The energy required to dissociate an ionic solid into gaseous ions (lattice energy) for the compounds NaF and MgF2 is shown in the table above. On the basis of Coulomb's law, which of the following best helps to explain the large difference between the lattice energies of NaF and MgF2 ? A. The solubility of MgF2MgF2 is less than that of NaFNaF. B. The electronegativity of MgMg is greater than that of NaNa. C. The mass of the MgMg cation is greater than that of the NaNa cation. D. The charge of the MgMg cation is larger than that of the NaNa cation.

D. The charge of the MgMg cation is larger than that of the NaNa cation.

(Lewis Diagrams of Hydrocarbons) Lewis diagrams of molecules of three different hydrocarbons are shown above. Which of the following claims about the molecules is best supported by the diagrams? A. All the atoms in molecule 1 lie in one plane. B. All the molecules have the same empirical formula. C. The C-C-CC-C-C bond angle in molecule 2 is close to 180°180°. D. The strongest carbon-to-carbon bond occurs in molecule 3.

D. The strongest carbon-to-carbon bond occurs in molecule 3. (contains a tripe bond)