F321 june 09 questions

Question 1

Explain why the first ionisation energies show a general increase from Li to Ne. (3)

Answer 1

• radii decreases
• nuclear charge increases
• shielding remains the same

Question 2

Explain the difference between the first ionisation energies of Li and Na. (3)

Answer 2

• atomic radii increase 
• there is more shielding
• the nuclear attraction decreases OR Increased shielding

Question 3

Suggest why the second ionisation energy of oxygen has a greater value than the first ionisation energy of oxygen.(1)

Answer 3

the O+ ion, is smaller than the O atom

Question 4

Explain why the halogen’s boiling points increase down the group (3)

Answer 4

• London forces
• number of electrons increases 
• down the group, more energy needed to break London forces