Lecture 16

Question 1

Bond energy

Answer 1

Energy required to overcome the electrostatic attraction of a bone and separate its components ae isolated atoms

Question 2

Bond length

Answer 2

Distance between nuclei at which potential energy is lowest

Question 3

Bond order

Answer 3

The number of electron pairs being shared by a given pair of atoms

Question 4

If bond order increases…then

Answer 4

• bond length decreases
• bond energy increases

Question 5

Bond energy and bond length have a ____ relationship

Answer 5

Inverse

Question 6

Atomic radius periodic table trend

Answer 6

Increases down, increases to the left

Question 7

Bond length periodic table trend

Answer 7

Increases down, increases left

Question 8

Bond energy periodic table trend

Answer 8

Increases up, increases right

Question 9

Why are longer bonds weaker?

Answer 9

• less overlap of e-
• same # of valence electrons over larger volume
• larger atoms have weaker bonds (lower e- density)

Question 10

Intramolecular

Answer 10

Forces exist between atoms within a molecule

Question 11

Intermolecular

Answer 11

Forces exist between the molecules themselves

Question 12

How strong are covalent bonds?

Answer 12

Very strong

Question 13

Solid state chemistry

Answer 13

A continuous network of covalent bonds

Question 14

Examples of covalent solids

Answer 14

Quartz and diamond

Question 15

Hess’s Law for bond breaking (the equation)

Answer 15

ΔHrxn = ΣBE(reactant bonds broken) - ΣBE (product bonds broken)

Question 16

Bond energies: Heat is released if…

Answer 16

• Exothermic (-ΔH)
• the total energy of bonds formed is greater than the total energy of bonds broken

Question 17

Bond energies: Heat is absorbed if…

Answer 17

• endothermic
• the total energy of bonds formed is less than the total energy of bonds broken (+ΔH)