Week 4 (1)

Question 1

What is covalent bonding?

Answer 1

A covalent bond arises from a shared pair of electrons

Question 2

How many covalent bonds are formed by:

H

C

N

O

F

Answer 2

1

4

3

2

1

Question 3

What charged ion does Zn tend to form?

Answer 3

Zn 2+

Question 4

What charged ions does Ni tend to form?

Answer 4

Ni 2+

Question 5

What charged ions does Mn tend to form?

Answer 5

Mn 2+ Mn 3+ Mn 7+

Question 6

What charged ions does Fe tend to form?

Answer 6

Fe 2+

Fe 3+

Question 7

What charged ions does cobalt tend to form?

Answer 7

Co 2+ Co 3+

Question 8

What charged ions doe copper tend to form?

Answer 8

Cu+

Cu 2+

Question 9

What charged ion does Cd tend to form?

Answer 9

Cd 2+

Question 10

What charged ion does Hg tend to form?

Answer 10

Hg 2+

Question 11

What charged ion does Al tend to form?

Answer 11

Al 3+

Question 12

How can structure affect the strength of a hydrogen bond?

Answer 12

Electronegative atom with a hydrogen attached close to another electronegative atom preferably all in a straight line (bond angle of 180 degrees) will make the hydrogen bond stronger

Question 13

What do Van der Waals Forces involve? Are they stronger/ weaker than hydrogen bonds?

Answer 13

• Weak bonds which exist between all molecules
• electrons are constantly moving which causes involves instantaneous dipoles that induce dipoles in neighbouring molecules
• Weaker than hydrogen bonds

Question 14

Van der Waals : What causes uneven distributions of the electronic charge (polarity)?

Answer 14

Oscillations of electrons cause transient, uneven distributions of the electronic charge (polarity)

Question 15

Van der Waals: what makes these attractions stronger?

Answer 15

When molecules have large surface areas that can come into close contact, the total attraction from such interactions can be VERY LARGE.

Question 16

What compound is Van der Waals important for?

Answer 16

The 3D shape of a protein molecule is essential for its correct functioning, and Van der Waals forces are important in maintaining this shape.

Question 17

Water has an ordered structure because of

Answer 17

hydrogen bonding

Question 18

What happens to hydrogen bonds when a solute is dissolved in it?

Answer 18

involves breaking these hydrogen bonds – costs energy

Question 19

What property allows for interactions with an aqueous medium?

Answer 19

The more polar, hydrophilic side chains tend to be on the surface

Question 20

What do Hydrophobic portions of bio-molecules tend to associate with?

Answer 20

-each other because they “cannot pay the energy cost.” - Hydrophobic amino acid side-chains in globular proteins tend to associate with the hydrophobic core.

Question 21

What do polar compounds usually have?

Answer 21

usually contain electronegative atoms, hydrogen bonding groups or charged groups.

Question 22

What do non polar compounds usually lack?

Answer 22

usually deficient in electronegative atoms, hydrogen bonding groups or charged groups.

Question 23

Name 6 key points about bonding in biological compounds?

Answer 23

1. A covalent bond arises from the SHARING of a PAIR of electrons.
2. Hydrogen bonding arises from a polarisation of covalent bonds by electronegative atoms.
3. Hydrogen bonds are MUCH WEAKER than covalent bonds.
4. Ionic bonding results from the transfer of an electron or electrons from one atom to another.
5. Hydrophobic portions of bio-molecules tend to associate with each other because they cannot pay the energy cost of breaking the hydrogen bonding present in water.
6. Van der Waals forces are weak, transient but very important in large molecules.

Question 24

Classify these compounds into polar and non-polar comppounds

Answer 24