$$\Delta H_{rxn} = \sum D \text{(bonds broken)} - \sum D \text{(bonds formed)}$$

Question 1

Which of the following best describes the lattice energy of an ionic compound?

Accepted Answer

The energy released when a mole of gaseous ions forms a solid ionic compound.

Question 2

According to Coulomb’s law, which factor will increase the lattice energy of an ionic compound?

Accepted Answer

Increasing the charge on the ions.

Question 3

Which of the following molecules is an exception to the octet rule because it has fewer than eight electrons around the central atom?

Accepted Answer

BF3

Question 4

What is the correct formula for calculating the dipole moment ($$\mu) of a $$molecule?

Accepted Answer

$$\mu = Qr$$

Question 5

Which statement about bond enthalpy is correct?

Accepted Answer

Bond enthalpy is the energy required to break a specific bond in one mole of gaseous molecules.

Question 6

Which of the following best explains why the reaction between sodium metal and chlorine gas to form sodium chloride is so exothermic?

Accepted Answer

The electrostatic attraction between the newly formed sodium cation and chloride anion.

Question 7

Which of the following is NOT a basic type of chemical bond?

Accepted Answer

Hydrogen bond

Question 8

Which molecule has a polar covalent bond but is overall non-polar due to its geometry?

Accepted Answer

CO2

Question 9

What is the correct sequence of steps for writing a Lewis structure for a polyatomic ion?

Accepted Answer

Add up valence electrons, connect atoms by single bonds, fill octets of outer atoms, fill octet of central atom, form multiple bonds if needed.

Question 10

Which of the following statements about resonance structures is TRUE?

Accepted Answer

Resonance structures are attempts to represent a real structure as a blend between several extreme possibilities.

Question 11

Which of the following is the best Lewis structure for a molecule, according to the rules for formal charge?

Accepted Answer

The structure with the lowest formal charge on each atom and the most negative formal charge on the most electronegative atom.

Question 12

Which of the following molecules is an exception to the octet rule because it has more than eight electrons around the central atom?

Accepted Answer

PCl5

Question 13

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

Accepted Answer

Triple bonds are shorter and stronger than single bonds.

Question 14

Which of the following best describes a coordinate covalent bond?

Accepted Answer

A bond in which both electrons shared come from the same atom.

Question 15

Which of the following is the correct formula for estimating the enthalpy of a reaction using bond enthalpies?

Accepted Answer

$$\Delta H_{rxn} = \sum D 	ext{(bonds broken)} - \sum D 	ext{(bonds formed)}$$

Question 16

Which of the following statements about electronegativity is correct?

Accepted Answer

Electronegativity increases from the bottom to the top of a column.

Question 17

Which of the following molecules will have a tetrahedral electron domain geometry but a trigonal pyramidal molecular geometry?

Accepted Answer

NH3

Question 18

Which of the following is TRUE about the effect of lone pairs on molecular geometry?

Accepted Answer

Lone pairs decrease bond angles because they exert greater repulsive forces than bonding pairs.

Question 19

Which of the following is a real-world example of a molecule with resonance structures?

Accepted Answer

Ozone ($$O_3)$$

Basic Concepts of Chemical Bonding: Ionic, Covalent, and Metallic Bonds, Lewis Structures, and Molecular Geometry

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