Practice Exam Questions

Question 1

Is a carbocation an electrophile or a nucleophile?

Answer 1

Electrophile

Question 2

Is a carbocation a Lewis acid or Lewis base?

Answer 2

Lewis acid

Question 3

Describe the bonding responsible for the formation of alpha-helices and beta-pleated sheets

Answer 3

Alpha-helices: intramolecular hydrogen bondins

Beta-pleated sheets: intermolecular hydrogen bonding

Question 4

True or False: the hydroxyl groups on the left of a Fischer projection point up in a Haworth projection

Answer 4

True

Question 5

Define a heterocyclic molecule

Answer 5

A cyclic molecule containing carbon and at least on hetero atom such as O, N or S

Question 6

What is the full name for the sugar in DNA?

Answer 6

2-deoxy-D-ribose

Question 7

How do amino acids bind to metals?

Answer 7

Via heteroatoms on side-chains, such as N, O or S

Question 8

What is the atomic size trend from 3d to 5d elements?

Answer 8

There is very little different unlike the main group elements (which increase in size down a group). The 4f electrons shield the 5d electrons

Question 9

How does atomic size change for the 3d series from left-to-right across the period, and why?

Answer 9

Atomic size decreases due to increasing nuclear charge from left to right

Question 10

Besides iron, what are the next two most abundant transition metal ions in the human body?

Answer 10

Zinc and copper

Question 11

Briefly describe the mode of bonding of oxygen to the iron centre in one haem unit of haemoglobin

Answer 11

• Fe metal centre. Fe2+, d6 in deoxy form
• Upon binding oxygen
• Redox: Fe3+ and O2)-
• From high spin to low spin
• Fe ion goes from slightly above the plane of porphyrin ring to being smaller and fitting into ring