Intermolecular & Non-Covalent Forces

Question 1

What are intramolecular bonds?

Answer 1

Bonds within a molecule

Question 2

What are intermolecular bonds?

Answer 2

Bonds between different molecules

Question 3

What are the five types of non-covalent (Van Der Waals) forces?

Answer 3

1. Dispersion forces
2. Hydrophobic forces
3. Permanent dipole interactions
4. Hydrogen bonds
5. Ionic interactions

Question 4

What are dispersive forces?

Answer 4

Dipole-induced dipole attraction - unevenly distributed electrons in orbitals cause a polar molecule with partial charged, with can create an induced dipole

Question 5

What is an induced dipole?

Answer 5

A polar molecule induces a dipole in a neighbouring molecule by disturbing its electron arrangement

Question 6

Are dispersive forces short or long lived?

Answer 6

They are short lived

Question 7

Are dispersive forces strong or weak?

Answer 7

Very weak

Question 8

Do dispersive forces work over long or short distances?

Answer 8

Short

Question 9

What does hydrophobic mean?

Answer 9

‘Hate’ water and moves away from it

Question 10

What does hydrophilic mean?

Answer 10

‘Loves’ water and moves toward it

Question 11

What part of a phospholipid is hydrophobic?

Answer 11

The tails

Question 12

What part of a phospholipid is hydrophilic?

Answer 12

The head

Question 13

What do permanent dipole (or dipole-dipole) interactions require?

Answer 13

A permanent dipole from a partial charge on a covalent bond

Question 14

Are permanent (or dipole-dipole) interactions long or short lived?

Answer 14

Long lasting

Question 15

What is the strength of a dipole-dipole attraction determined by?

Answer 15

The electronegativity of the atoms within the dipole-dipole

Question 16

Hydrogen bonds are a type of what interaction?

Answer 16

Dipole-dipole

Question 17

In hydrogen bonding, hydrogen must bond to what?

Answer 17

N, O, F

Question 18

In hydrogen bonding, H bonds to one of three elements. What type of electron pair is formed on these elements when bonded?

Answer 18

A lone pair

Question 19

What is the species called that donates a hydrogen to a hydrogen bond?

Answer 19

A donor species

Question 20

Give some examples where hydrogen bonding occurs.

Answer 20

1. Between the hydroxyl group of an alcohol and water
2. Between the carbonyl group of a ketone and water
3. Between peptide groups in polypeptides
4. Between complementary bases of DNA

Question 21

What are ionic interactions?

Answer 21

Attractions between ionic species or ionic ‘parts’ of a molecule. Formed as a result of a permanent transfer of electrons

Question 22

Are ionic interactions short or long lived?

Answer 22

Longer lasting

Question 23

Do ionic interactions tend to be weaker or stronger?

Answer 23

Stronger

Question 24

Van Der Waals forces determine what physical characteristic of molecules?

Answer 24

The boiling point

Question 25

If there are many, compact Van Der Waals forces within a molecule, what state will a molecule be at room temp?

Answer 25

A solid

Question 26

If there are few Van Der Waals forces within a molecule, what state will a molecule be at room temp?

Answer 26

A liquid

Question 27

If there are hardly any Van Der Waals forces within a molecule, what state will a molecule be at room temp?

Answer 27

A gas

Question 28

Three molecules contain different Van Der Waals forces: One with dipole-dipole, one with H bonds, and one with ionic bonds. Order them from lowest boiling point to highest.

Answer 28

Lowest - Dipole-dipole
H bonds
Highest - Ionic bonds