1.10: MEtallic and Intermolecular Bonding

Question 1

What are the 2 requirements for metaillic bonding?

Answer 1

1. Low ionisation energies
2. Vacant valance orbitals

Question 2

What are the 4 characteristics of metals?

Answer 2

1.(Mostly) Great streghth - Dependent on packing and number of electrons
2. Good conducters of heat and electricity in solid and liquid state
3. Malleable and ductile
4. Lustrous (shiny)

Question 3

Where are intramolecular bonds found?
Examples?

Answer 3

Within a molecule - hold atoms together

Polar and non-polar covelant bonds

Question 4

Where are intermolecular bonds found?
Examples?

Answer 4

Between molecules - hold molecules together

Dipole - dipole bonds
Hydrogen bonds

Question 5

List the intermolecular forces in order of stregnth

Are they polar or non polar molecules?

Answer 5

1. Ion-Dipole forces
2. Hydrogen Bonds
3. Dipole-Dipole forces
   4.Dispersion forces - Van der Waals/London forces

1,2 and 3 are polar
4 is non polar

Question 6

What are Londan dispersion forces?
Trend in stregnth?

Answer 6

Instantaneous dipole- induced dipole interaction

Their stregth increases with number of electrons

Question 7

What is a dipole-dipole interaction?

Answer 7

Electrostatic attracttion between parmanent dipoles

Question 8

What are the properties of a dipole-dipole interaction?
What are they significant in?

Answer 8

• Act in addition to London Van der Waals interactions
• Result in higher boiling points than expected from the mass of the molecule

Significance in:
- Carbonyls
- Protein folding

Question 9

What is an Ion-dipole force?
What does its stregnth depend on?

Answer 9

Electrostatic force of attraction between an ion and an uncharged polar molecule

Stregnth depends on charge of ion and magnitude of dipole

Question 10

What 2 things does Hydrogen bonding require?

Answer 10

1. A δ+ hydrogen atom (donor)
2. An electronegative atom (acceptor)

Question 11

What characteristics are essential for electronegative atoms in hydrogen bonding?
Examples?

Answer 11

• Small size
• High charge density
• Lone pair of electrons in small orbital

oxygen, nitrogen, or fluorine δ-

Question 12

Give an example of an INTRAmolecular hydrogen bond.
Give its melting point

Answer 12

o-nitrophenol
Mp: 43-45 °C

Question 13

Give an example of an INTERmolecular hydrogen bond.
Give its melting point

Answer 13

p-nitrophenol
Mp 110-115 °C

Question 14

Describe the bonding in water

Answer 14

Each water molecule is hydrogen-bonded to 4 water molecules in a
tetrahedral formation

Question 15

Compare H-bonds in water and ice

Answer 15

Water; H-bonds break and reform
Ice; Fixed arrangement of H-bonds

Question 16

Compare the structures of water and ice

Answer 16

Water - Disorganised
Ice - Diamond like crystal structure

Molecules in ice are further apart - larger volume and lower density

Question 17

SLIDE 16

Answer 17

CHECK AND LEARN IF NEED BE

Question 18

How does hydrogen bonding form in DNA between bases?

Answer 18

Adenine - Thymine
Guanine - Cytosine

Matching number of hydrogen bond donors and acceptors allows ‘correct’ pairing of DNA bases

Question 19

What structures does hydrogen bonding create in proteins?

Answer 19

Alpha helix and beta pleated sheets

Strongest interactions between amide (N-H) and C=O

Question 20

Where is celululose found and used?

Answer 20

Major component of plant cell walls, found in wood and plant fibres

Its derivatives are used in textiles, toiletries and food products

Question 21

What are the 3 properties of cellulose?

Answer 21

1. Its a polymer of glucose
2. Sugar chains are held rigidly
   together by multiple hydrogen
   bonds within and between chains

3.Flat sheets of hydrogen-bonded
chains are held together by
London dispersion (VdW) forces.

Question 22

Learn solubility slide 20

Answer 22

Sodium chloride
Ethanol
Hexane