Chapter 3

Question 1

Which elements have an incomplete octet?

Answer 1

Hydrogen - 2 electrons 
Helium - 2 electrons 
Lithium- 2 electrons 
Beryllium- 4 electrons 
Boron- 6 electrons

Question 2

Which elements have an expanded octet ?

Answer 2

Any element in period 3 or greater

Question 3

How many electrons do P, S and Cl hold ?

Answer 3

10, 12, 14

Question 4

What is a nonpolar covalent bond ?

Answer 4

Electrons are equally shared

Question 5

What is a polar covalent bond ?

Answer 5

Electrons are shared unequally

Question 6

Coordinate covalent

Answer 6

If both shared electrons are contributed by one of the two atoms

Question 7

Cation

Answer 7

Metal lose electrons

Question 8

Anion

Answer 8

Nonmetal gain electrons

Question 9

What are the five characteristics of ionic bonds ?

Answer 9

1. High melting and boiling point
2. Highly soluble in water
3. Good conductors of heat and electricity
4. Large electronegativity difference between ions
5. Crystal lattice arrangement as solids to maximize attraction

Question 10

What are the characteristics of covalent bonds ?

Answer 10

1. Lower melting and boiling point
2. Don’t break down into ions
3. Poor conductors of heat and electricity in
   Iiquid or aqueous state

Question 11

Bond order

Answer 11

Shared electron pairs between two atoms

Single bond- 1
Double bond - 2
Triple bond- 3

Question 12

Bond energy

Answer 12

Energy required to break a bond

Question 13

What electronegativity difference is generally considered non polar ?

Answer 13

0.5

Question 14

What electronegativity difference is considered polar ?

Answer 14

0.5 to 1.7

Question 15

What is the equation for dipole moment ?

Answer 15

p= qd

p = dipole moment
q=magnitude of charge
d= displacement vector that separates two charges

Question 16

Lewis base

Answer 16

Donates a pair of electrons

Question 17

Lewis acid

Answer 17

Accepts a pair of electrons

Question 18

Formal charge formula

Answer 18

Formal charge = valence electrons - Nnonbonding - 1/2Nbonding

Question 19

What is the criteria for Lewis structures ? Which Lewis structure is preferred ?

Answer 19

1. Small or no formal charge
2. Less separation between opposite charges
3. Negative formal charges are placed on more electronegative atoms

Question 20

What is the ideal bond angle for tetrahedral geometry ?

Answer 20

109.5 degrees

Question 21

What are the three types of electrostatic interactions and rank them from strongest to weakest?

Answer 21

1. Hydrogen bond
2. Dipole- dipole interactions
3. London dispersion forces

Question 22

London dispersion forces

Answer 22

Short lived induced dipoles that extend over short distance. Larger molecules have greater dispersion forces

Question 23

Dipole dipole interactions

Answer 23

Polar molecules orient themselves in a way in which the negative dipole interacts with positive

Last longer than London dispersion

Question 24

Hydrogen bond

Answer 24

Strong dipole dipole interactions that are specific to hydrogen binding to fluorine , oxygen and nitrogen . They are intermolecular or intramolecular .

Question 25

What are the five VSEPR shapes and their corresponding angles

Answer 25

1. Linear- 180
2. Trigonal planar-120
3. Tetrahedral- 109.5
4. Regional bipyramidal - 90, 120, 180
5. Octahedral - 90, 180