Chapter 8: Basic Concepts of Chemical Bonding

Question 1

when comparing electronegativities, it is better to compare based on a periodic trend or to compare based on values from a table?

Answer 1

vales from the table.

Trends don’t seem very strict for this property

Question 2

What’s a good way to predict that a central atom will have an expanded octet?

Answer 2

If it has an atomic number of 15 or greater

Question 3

What does a dipole describe

Answer 3

any 2 charges with equal magnitude by opposite signs (like a to sided pole; di-pole)

Question 4

what 3 types of bonding does the octet rule NOT apply to?

Answer 4

1. Bonds involving ionic compounds
2. Bonds involving transition metals
3. Some Bonds involving covalent bonds

Question 5

Do weak covalent bonds (in molecules) make the molecules more reactive or less reactive?

Answer 5

More

If the bonds are weak, they are easy to break in order to make bonds with other atoms/molecules or to make new molecules

Question 6

What is the electronegativity value for hydrogen?

Answer 6

2.1

Question 7

Does bond enthalpy (for covalent bonds) apply to solids, liquids or gasses?

Answer 7

it applies to kj/mol of substances in GAS phase

Question 8

Does the covalent nature of bonds involving metals go up as the metal’s oxidation number goes up?

Answer 8

yes, generally speaking

exp. Mn2O7 is covalent, not ionic (as the Mn oxi. number is 7)

Question 9

Do bond enthalpies for covalent bonds represent exact values or average values?

Answer 9

average

Question 10

How many covalent bonds does nitrogen usually make?

Answer 10

3

Question 11

Why does nitrogen (and other group 15 elements) make triple bonds in molecules/compounds?

Answer 11

this enables it to have a formal charge of 0

Question 12

Does the octet rule generally apply to transition metals?

Answer 12

No

Question 13

What factor (other than electronegativity) impacts the polarity of bonds in structures containing metal?

Answer 13

the oxidation number of the metal

Question 14

What range of electronegativity differences would make a bond be described as super polar (ionic)?

Answer 14

above 1.7 to infinity

Question 15

What are the 3 atoms that Chase said always break the octet rule by not having enough valence electrons?

2,4,6…

Answer 15

Hydrogen (only has 1 electron)
Helium (is noble but only has 2 electrons)
Beryllium (only has 2 VALENCE electrons)
Boron (only has 3 VALENCE electrons)

Question 16

what is the lewis structure for CO

Answer 16

:C triple bond O:

Question 17

what is the difference between a dipole and a dipole moment?

Answer 17

A dipole tells you that opposing charges are present, but the dipole MOMENT tells you the magnitude of that opposition

Question 18

Does having multiple bonds (i.e. double or triple bonds) make a molecule’s bond enthalpy higher or lower?

Answer 18

Higher. The more bonds you have, the more energy it takes to break them/the harder they are to break

Question 19

What is a good way to predict that atoms in a molecule or polyatomic ion’s will break the octet rule?

Answer 19

If the molecule/ion’s TOTAL number of valence electrons is odd

exp. ClO2, NO, NO2, O2-

Question 20

What is the equation for estimating lattice energy?

Answer 20

E = [k(Q1Q2)]/d

Question 21

What does a dipole moment describe/quantify?

Answer 21

the polarity of a bond between elements

Question 22

What does formal charge describe?

Answer 22

the difference between the number of electrons surrounding a given atom in a molecule/compound, and the number of valence e- it would have if it was a lone, neutral element

Question 23

What range of electronegativity differences would make a bond be described as NON-polar covalent?

Answer 23

0 to 0.5

Question 24

What range of electronegativity differences would make a bond be described as POLAR covalent?

Answer 24

above 0.5 to 1.7

Question 25

Do molecules/structures with covalent bonds generally have high melting and boiling points or low melting and boiling points?

Answer 25

relatively low