$$\Delta H = \sum \text{(bond energies of bonds broken)} - \sum \text{(bond energies of bonds formed)}$$

$$\text{Na}$$ and $$\text{Cl}$$

Question 1

Which statement best describes the formation of a chemical bond according to Lewis theory?

Accepted Answer

A chemical bond forms when the attractive and repulsive interactions between two atoms result in a reduction of energy.

Question 2

Which of the following best describes an ionic bond?

Accepted Answer

Electrons are transferred from a metal atom to a nonmetal atom.

Question 3

Which type of chemical bond is described by the electron sea model?

Accepted Answer

Metallic bond

Question 4

Given the following electronegativity values: $$	ext{Cl} = 3.0$$, $$	ext{Br} = 2.8$$, $$	ext{I} = 2.5$$, which bond is expected to be the most polar?

Accepted Answer

$$	ext{Cl}-	ext{I}$$

Question 5

Which of the following compounds contains a pure (nonpolar) covalent bond?

Accepted Answer

$$	ext{H}_2$$

Question 6

What is the correct Lewis structure for methane ($$	ext{CH}_4$$)?

Accepted Answer

Central C atom with four single bonds to H atoms and no lone pairs on C.

Question 7

Which of the following is NOT a reasonable Lewis structure for a molecule containing C, H, and F?

Accepted Answer

A structure where F forms two single bonds with C and has four lone pairs.

Question 8

Which of the following best explains why the bond energy of a triple bond is greater than that of a double bond?

Accepted Answer

Triple bonds have more electrons shared, resulting in stronger attraction between atoms.

Question 9

Which equation correctly represents the calculation of the dipole moment ($$\mu) $$for a bond?

Accepted Answer

$$\mu = q 	imes r$$

Question 10

A molecule has a central atom with more than eight electrons in its valence shell. What is this an example of?

Accepted Answer

A hypercoordinate compound

Question 11

Which of the following trends is correct regarding lattice energy?

Accepted Answer

Lattice energy becomes less exothermic with increasing ionic radius.

Question 12

Using average bond energies, which formula is used to estimate the enthalpy change ($$\Delta H) $$for a reaction?

Accepted Answer

$$\Delta H = \sum 	ext{(bond energies of bonds broken)} - \sum 	ext{(bond energies of bonds formed)}$$

Question 13

Which of the following pairs of atoms will form an ionic bond based on their electronegativity difference?

Accepted Answer

$$	ext{Na}$$ and $$	ext{Cl}$$

Question 14

Which step is NOT part of drawing a Lewis structure for $$	ext{O}_2$$?

Accepted Answer

Assigning oxidation numbers to each atom.

Question 15

Which of the following statements about resonance structures is TRUE?

Accepted Answer

Resonance structures are a way to show delocalization of electrons within a molecule.

Question 16

Which of the following molecules is an example of an exception to the octet rule due to an odd number of electrons?

Accepted Answer

$$	ext{NO}$$

Question 17

What is the formal charge on the central oxygen atom in the best Lewis structure of ozone ($$	ext{O}_3$$)?

Accepted Answer

$$+1$$

Question 18

Which of the following best describes the bond in $$	ext{HCl}$$?

Accepted Answer

Polar covalent

Question 19

Which element is most likely to be the central atom in a hypercoordinate compound?

Accepted Answer

Phosphorus ($$	ext{P})$$

Chemical Bonding I: Lewis Theory – Study Notes

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