AP Chemistry- Unit 2
Of the following compounds, which is the most ionic?
CaCl2
Which of the following is isometric with CH3CH2CHO?
Ch3COCH3
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
Equally shared and form nondirectional bonds
The electron-dot structure (Lewis structure) for which of the following molecules would have two unshared pairs of electrons on the central atom?
H2S
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?
It contains ionic bonds
The lattice energy of a salt is related to the energy required to separate the ions. For which of the following pairs of ions is the energy that is required to separate the ions largest?
Mg2+ and O2-
Which of the following can be inferred from the diagram opposite that shows the dependence of potential energy on the internuclear distance between two atoms?
The atoms form a bond with a bond length of 75 pm
Resonance is most commonly used to describe the bonding in molecules of which of the following? A CO2 B O3 C H2O D CH4 E SF6
03
Which of the following molecules has an angular (bent) geometry that is commonly represented as a resonance hybrid of two or more electron-dot structures?
03
Which of the following diagrams best depicts an alloy of Ni and B?
A
Which of the following diagrams best illustrates how a displacement in an ionic crystal results in cleavage and brittleness?
A
The particle-level diagram opposite 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 (5 small positively charged ions, 4 large negatively charged ions)
The potential energy as a function of internuclear distance for three diatomic molecules, X2, Y2, and Z2, is shown in the graph opposite. Based on the data in the graph, which of the following correctly identifies the diatomic molecules, X2, Y2, and Z2?
A (H2, N2, 02)
The potential energy of a system of two atoms as a function of their internuclear distance is shown in the diagram opposite. Which of the following is true regarding the forces between the atos when their internuclear distance is x?
A (The attractive and repulsive forces are balanced, so the atoms will maintain an average internuclear distance x.)
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
Steel is an alloy consisting of Fe with a small amount of C. Elemental Cr can be added to steel to make the steel less likely to rust; Cr atoms react with oxygen in the air to form a nonreactive layer of chromium oxide on the surface of the steel, preventing the oxidation of underlying Fe atoms. A sample of steel-chromium alloy contains 15 percent Cr by mass. Which of the following diagrams best shows a particle-level view of a surface section and an interior section of the alloy represented below at the left? (The atomic radii of the atoms involved are given in the table below at the right.)
B
Steel is an alloy containing Fe atoms and C atoms. Which of the following diagrams represents the particle-level structure of steel?
B
Which of the following Lewis diagrams best represents the bonding in the N20 molecule?
B
Of the following diagrams, which best represents the structure of solid KF?
B (alternating pattern packed together)
Which of the following has a central atom with less than an octet of electrons?
BH3
Which of the following molecules contains only single bonds?
C2H6
Which of the following is an isomer of CH3OCH3?
CH3CH2OH
On the basis of the information opposite, which of the following arranges the binary compounds in order of increasing bond polarity?
CH4 < SiCl4 < SF4
To make Au stronger and harder, it is often alloyed with other metals, such as Cu and Ag. Consider two alloys, one of Au and Cu and one of Au and Ag, each with the same mole fraction of Au. If the Au/Cu alloy is harder than the Au/Ag alloy, then which of the following is the best explanation based on the information in the table above?
Cu atoms are smaller than Ag atoms, thus they interfere more with the displacement of atoms in the alloy
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?
D
Which of the following graphs correctly shows the relationship between potential energy and internuclear separation for two hydrogen atoms?
D (dip and level off under the 0 mark)
Which of the following has the bonds arranges in order of decreasing polarity?
H-F > N-F > F-F
Which of the following has two lone pairs of electrons?
H2O
The melting point of MgO is higher than that of NaF. Explanations for this observation include which of the following? I. Mg2+ is more positively charged than Na+ 2. O2- is more negatively charged than F- III. The O2- ion is smaller than the F- ion
I and II only
Which of the following correctly indicates whether the solid represented by the particulate model shown opposite conducts electricity and explains why or why not?
It does not conduct electricity because its ions cannot move freely within the solid.
Which of the following compounds contains both ionic and covalent bonds?
NH4Cl
Based on the data in the tables opposite, which of the following statements provides the best prediction for the boiling point of NaCl?
NaCl will have a lower boiling point than NaF because the coulombic attractions are weaker in NaCl than in NaF.
Of the following single bonds, which is the LEAST polar?
O-F
For which of the following molecules are resonance structures necessary to describe the bonding satisfactorily?
S02
Which of the following statements, if true, would support the claim that the NO3- ion, represented above, has three resonance structures?
The NO3- ion is not a polar species.
Which of the the following scientific claims about the bond in the molecular compound is most likely to be true?
The bond is highly polar
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?
The carbon to selenium bond is nonpolar covalent
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?
The charge of the Mg cation is larger than that of the Na cation.