Chapter 3

Question 1

Ionic Bonding

Answer 1

Bonds that form between ions
* Gain/loss of electrons
* Tend to form between metals and nonmetals because metals lose electrons (because have low ionization energies) and nonmetals gain electrons (because have high electron affinities) COMPLEMENTARY

Characteristics:
1. High melting & boiling points (due to electrostatic attractions)
2. Solubility of ions in water (due to interactions with polar solvents)
3. Good conductors of heat and electricity
4. Crystal lattice arrangement (to minimize repulsive forces)
5. Large electronegativity differences between ions

Electronegativity: 1.7 or higher

Question 2

Covalent Bonding

Answer 2

Bonds that form when electrons are shared between atoms
* Polarity: determined by differences in electronegativity between two atoms

Question 3

Octet Rule

Answer 3

Atoms tend to bond with other atoms to have eight electrons in its valence shell

Question 4

Octet Rule Exceptions

Answer 4

1. Incomplete Octet
   * Stable with fewer than 8 electrons in valence shell
   * Ex: H (2), He (2), Li (2), Be (4), B (6)
2. Expanded Octet
   * Any element in period 3 and greater can hold more than 8 electrons
   * Ex: P (10), S (12), Cl (14)
3. Odd numbers of electrons:
   * Any molecule with odd number of valence electrons can’t distribute electron to give eight to each atom
   * Ex: Nitric Oxide (NO)

Question 5

Bond Strength

Answer 5

Electrostatic attraction between nuclei and electrons
* Multiple bonds (higher bond order) increases strength

Question 6

Bond Length

Answer 6

Consequence of attractions
* Stronger the bond = shorter
* Shortest = triple, then double, then single
* If can’t compare based off bond order, compared based off electronegativity

Question 7

Bond Energy

Answer 7

Minimum amount of energy needed to break a bond
* Stronger bond = higher bond energy
* Highest energy: triple, then double, then single

Question 8

Nonpolar Covalent Bonds

Answer 8

Atoms that have identical/almost identical electronegativities sharing electron paris with equal distribution
* Electronegativity: 0 to 0.5

Question 9

Polar Covalent Bonds

Answer 9

Atoms that differ moderately in electronegativities and share electrons unevenly
* Electronegativity: 0.5 to 1.7

Question 10

Formal Charge

Answer 10

Valence electrons - nonbonding electrons - 1/2 * (bonding electrons)

Question 11

Formal Charge

Answer 11

Valence electrons - nonbonding electrons - 1/2 * (bonding electrons)

Question 12

VSEPR Theory

Answer 12

Question 13

Hydrogen Bonding

Answer 13

Unusually strong form of dipole-dipole interaction that can be intra/intermolecular
* Hydrogen bonded to very electronegative atom (ex: N, O, F)
* Strongest intermolecular force

Question 14

Dipole-Dipole Interactions

Answer 14

Polar molecules orienting themselves so oppositely charged ends of molecular dipoles are closest to each other (+ close to -
)
Dipole: Segment of a molecule with partial positive and partial negative regions
* Second strongest intermolecular force

Question 15

London Dispersion Forces

Answer 15

Attractive interactions of short-lived and rapidly shifting dipoles
* Weakest intermolecular force
* Only molecular force noble gases experience
* Small but necessary for condensation to liquid

Question 16

Resonance Structures

Answer 16

Different forms an atom can take on by moving lone pairs and bonds
Most stable: minimize formal charges

Question 17

Coordinate Covalent Bonds

Answer 17

Single atom provides both bonding electrons while the other atom doesn’t contribute any
* Often in Lewis acid-base chemistry
* Commonly adding H+