L10: Metallic & Intermolecular Bonding

Question 1

Describe the interactions in metallic bonding

Answer 1

Electrostatic attraction between metal ions and mobile, delocalised electrons

Question 2

What are delocalised electrons?

Answer 2

They are not associated with a particular atom

Question 3

What are the prerequisites for metallic bonding to occur?

Answer 3

1) The metal should have low ionisation energies (able to give up their electrons to form positive metal ions)
2) The metal should have vacant valence orbitals to allow free movement of electrons

Question 4

Fill in the gap:

Metallically bonded compounds are __(1)__ conductors of heat and electricity in in solid and __(2)__ state

Answer 4

(1) good

(2) liquid

Question 5

Comment on the lustre of metallic compounds

Answer 5

Metallic compounds have a high lustre

Question 6

True or false: Metallic compounds are relatively malleable and ductile

Answer 6

True

Question 7

What are intramolecular forces?

Answer 7

Bonds holding atoms together within a molecule

Question 8

What are intermolecular forces?

Answer 8

Attractive forces between molecules

Question 9

Which is stronger, intermolecular or intramolecular forces?

Answer 9

Intramolecular

Question 10

What are the four types of intermolecular forces? List in order of strength (strongest first)

Answer 10

1) Ion-dipole
2) Hydrogen bonds
3) Dipole-dipole
4) Dispersion

Question 11

Which bonds form between polar molecules?

Answer 11

Ion-dipole, hydrogen, and dipole-dipole

Question 12

Which bonds form between non-polar molecules?

Answer 12

Dispersion (van der Waals/London)

Question 13

True or false: London dispersion forces are formed between temporary dipoles. These dipoles come about because of the uneven distribution of electrons in their orbitals

Answer 13

True

Question 14

True or false: London dispersion forces form between temporary dipoles

Answer 14

True

Question 15

True or false: Dipole-dipole interactions form between temporary dipoles

Answer 15

False. They relate to permanent dipoles

Question 16

True or false: Dipole-dipole interactions act in addition to Van der Waals

Answer 16

True

Question 17

How do dipole-dipole interactions effect boiling point?

Answer 17

Result in higher BP than expected from the mass of the molecule

Question 18

In which two areas are dipole-dipole interactions significant?

Answer 18

1) Carbonyls

2) Protein folding

Question 19

Fill in the gaps:

__(1)__-dipole forces are electrostatic interactions between an __(2)__ and an __(3)__ __(4)__ molecule

Answer 19

(1) ion
(2) ion
(3) uncharged
(4) polar

Question 20

What factor effects the strength of an ion-dipole bond?

Answer 20

Strength depends on the charge on the ion and the magnitude of the dipole

Question 21

Where are ion-dipole forces most common?

Answer 21

In solution.

E.g. NaCl dissolving in water

Question 22

What are the two requirements for a hydrogen bond?

Answer 22

1) An electronegative atom (O, N, or F) to act as the acceptor
2) A hydrogen atom in a polar bond (N-H, O-H, or F-H) to act as the donor

Question 23

True or false: Hydrogen bonds are stronger than other dipole-dipole interactions

Answer 23

True

Question 24

True or false: Hydrogen bonds are non-directional

Answer 24

False. Hydrogen bonds are directional

Question 25

True or false: Although they are relatively strong for intermolecular forces, hydrogen bonds are weak and easily broken compared to covalent bonds

Answer 25

True

Question 26

Give six areas in which hydrogen bonding plays a significant role

Answer 26

1) Physical state of water 2) Stabilise macromolecules 3) DNA double helix, base pairing 4) Protein secondary structure; alpha helices, beta sheets 5) Enzyme-substrate and antibody-antigen interactions 6) Solubility of compounds in water

Question 27

Why does water form such an extensive network of hydrogen bonds?

Answer 27

Each oxygen atom has two lone pairs and each molecule has two hydrogen atoms

Question 28

True or false: The base pairs match each other based on the number of hydrogen bonds each can donate/accept

Answer 28

True

Question 29

True or false: In alpha helices and beta sheets, hydrogen bonds form between amine (N-H) and C=O

Answer 29

True

Question 30

In addition to hydrogen bonds, what links can be formed by covalent and ionic bonding in secondary protein structures?

Answer 30

Covalent disulphide links (R-S-S-R) Ionic salt bridges (---CO2----NH3----

Question 31

Which intermolecular bonds hold sugar chains together in cellulose to form flat sheets?

Answer 31

Hydrogen bonds

Question 32

Which intermolecular bonds hold flat sheets of hydrogen-bonded sugar chains together in cellulose?

Answer 32

Van der Waals