Question 1

Which of the following best explains why chemical bonds form between atoms?

Accepted Answer

Because chemical bonds lower the potential energy between charged particles that compose atoms.

Question 2

Which type of bond is formed when a metal reacts with a nonmetal, and what is the primary process involved?

Accepted Answer

Ionic bond; electrons are transferred from the metal to the nonmetal.

Question 3

Which of the following statements about lattice energy is correct?

Accepted Answer

Lattice energy is the energy associated with forming a crystalline lattice of alternating cations and anions from gaseous ions.

Question 4

Rank the following compounds in order of increasing lattice energy: CaO, KBr, KCl, SrO.

Accepted Answer

KBr \u003c KCl \u003c SrO \u003c CaO

Question 5

Which property is NOT characteristic of ionic compounds?

Accepted Answer

Good conductor of electricity as a solid

Question 6

Which of the following molecules contains a polar covalent bond?

Accepted Answer

$$\mathrm{HF}$$

Question 7

Given the following electronegativity differences, classify the bond type: $$\Delta EN = 1.5.$$

Accepted Answer

Polar covalent

Question 8

Which of the following best describes the octet rule?

Accepted Answer

Atoms are most stable when they have 8 valence electrons.

Question 9

Which of the following molecules is an exception to the octet rule due to having fewer than 8 electrons around the central atom?

Accepted Answer

$$\mathrm{BF_3$}$$

Question 10

Which statement about resonance structures is correct?

Accepted Answer

Resonance structures are different valid Lewis structures for the same compound, differing only in the placement of electrons.

Question 11

What is the formal charge on the central atom in $$\mathrm{SO_3$} if $$the Lewis structure has all single bonds and all oxygens have full octets?

Accepted Answer

+2

Question 12

Which of the following best describes a metallic bond?

Accepted Answer

Electrons are pooled and delocalized among a lattice of metal cations.

Question 13

Which of the following molecules is polar?

Accepted Answer

$$\mathrm{NH_3$}$$

Question 14

Which of the following statements about bond length is correct?

Accepted Answer

Bond length decreases as the number of shared electrons increases.

Question 15

Which of the following best describes a sigma ($$\sigma) $$bond?

Accepted Answer

A bond formed by the end-to-end overlap of orbitals along the axis connecting two nuclei.

Question 16

Which of the following is true about molecular orbital theory?

Accepted Answer

Bonding molecular orbitals have lower energy than the original atomic orbitals.

Question 17

Calculate the bond order for $$\mathrm{O_2$}$$ using molecular orbital theory, given that it has 10 electrons in bonding orbitals and 6 in antibonding orbitals.

Accepted Answer

$$2$$

Question 18

A molecule has a measured dipole moment of $$2.0\ \mathrm{D}$$ and a bond length of $$120\ \mathrm{pm}. $$What is the magnitude of the partial charge $$q (in $$Coulombs) on each atom? (Use $$1\ \mathrm{D} = 3.336 	imes 10$$^{-30}$$\ \mathrm{C} \cdot \mathrm{m})$$

Accepted Answer

$$5.56 	imes 10$$^{-20}$$\ \mathrm{C}$$

Question 19

Which of the following statements about hybridization is correct?

Accepted Answer

Hybridization involves the mixing of atomic orbitals to form new hybrid orbitals of equal energy.

Question 20

Which of the following best explains why $$\mathrm{H_2O} is a $$polar molecule, while $$\mathrm{CO_2$} is $$nonpolar, even though both have polar bonds?

Accepted Answer

Because $$\mathrm{H_2O}$$ has an unsymmetrical shape, resulting in a net dipole moment, while $$\mathrm{CO_2$} is $$linear and symmetrical, causing the dipoles to cancel.

Chapter 10: Chemical Bonding and Molecular Structure

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