Question 1

Which of the following best explains why sodium chloride ($$\mathrm{NaCl}) $$forms a crystalline solid with a high melting point?

Accepted Answer

Because sodium and chloride ions are held together by strong electrostatic attractions in a crystal lattice.

Question 2

Which equation correctly represents the lattice energy ($$U) $$for an ionic compound, according to the Born-Haber cycle?

Accepted Answer

$$U = k \dfrac{Q_1$ Q_2$}{r}$$

Question 3

When two neutral atoms approach each other, which of the following best describes the energy changes that occur?

Accepted Answer

Potential energy decreases as attractive forces dominate until repulsion increases at very short distances.

Question 4

Which of the following compounds contains both ionic and covalent bonds?

Accepted Answer

$$\mathrm{Na_2SO_4}$$

Question 5

What is the correct name for the compound $$\mathrm{$$FeCl_3$$}$$?

Accepted Answer

Iron(III) chloride

Question 6

Which of the following is the correct formula for sulfuric acid?

Accepted Answer

$$\mathrm{H_2SO_4}$$

Question 7

Which of the following statements about the octet rule is correct?

Accepted Answer

Atoms tend to gain, lose, or share electrons to achieve eight electrons in their valence shell.

Question 8

Which of the following best describes the difference between valence and core electrons?

Accepted Answer

Valence electrons are in the outermost shell and participate in bonding, while core electrons are in inner shells and do not.

Question 9

How many molecules are present in 2.00 moles of $$\mathrm{CO_2$}$$? (Avogadro’s number $$= 6.022 	imes 10$$^{23}$$)

Accepted Answer

$$1.20 	imes 10$$^{24}$$

Question 10

What is the mass in grams of 0.50 moles of $$\mathrm{Na_2CO_3}$$? (Atomic masses: Na = 23, C = 12, O = 16)

Accepted Answer

53 g

Question 11

Which of the following bonds is the most polar?

Accepted Answer

$$\mathrm{H-F}$$

Question 12

Which of the following statements about electronegativity is correct?

Accepted Answer

Electronegativity increases across a period and decreases down a group.

Question 13

Which molecule exhibits resonance?

Accepted Answer

$$\mathrm{O_3$}$$

Question 14

Which Lewis structure is most stable based on formal charges?

Accepted Answer

The structure with the smallest formal charges and negative charges on the most electronegative atoms.

Question 15

Why are expanded octets possible for some elements?

Accepted Answer

Because elements in period 3 and beyond have available $$d$$ orbitals for bonding.

Question 16

Which of the following statements about bond order and bond length is correct?

Accepted Answer

As bond order increases, bond length decreases.

Question 17

What is the molecular geometry of $$\mathrm{BF_3$}$$?

Accepted Answer

Trigonal planar

Question 18

What is the bond angle in a tetrahedral molecule?

Accepted Answer

$$109.5^\circ$$

Question 19

Which of the following molecules is nonpolar despite having polar bonds?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 20

What is the steric number of the central atom in $$\mathrm{NH_4$^+}$$?

Accepted Answer

4

Chapter 4: Chemical Bonding, Molecular Structures, and Periodic Properties

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